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					                                                                                                            Comparative Bioavailability of Tramadol Contramid® Once-A-Day and Tramadol Immediate-Release Tablets
                                                                                                                                                               Presented at: The American Academy of Pain Medicine, 23rd Annual Meeting, February 7-10, 2007, New Orleans
                                                                                                                                                                                                                                                                                  David Karhu, BSc and Sylvie Bouchard, MD, PhD Labopharm Inc., Laval, Québec, Canada


ABSTRACT                                                                                                                                        RESULTS                                                                                                                                                                        Multiple-Dose Study                                                                                                                                           DISCUSSION
The bioavailability of Tramadol Contramid® Once a day (OAD) tablets and tramadol immediate-release (IR)                                         Single-Dose Study                                                                                                                                                                                                                                                                                                                            A once-daily formulation of tramadol (Ultram® ER, Ortho-McNeil Pharmaceutical Inc.) was recently introduced to the US
                                                                                                                                                                                                                                                                                                                                                Figure 3. Mean (SD) steady-state plasma tramadol concentrations on the                                                                       market.(10) Its pharmacokinetic profile is as follows:
(Ultram®) tablets was compared following single-dose administration and at steady state in two separate                                                         Figure 1. Mean (SD) plasma tramadol concentrations following single-dose                                                                                                        fifth day of multiple-dose administration of 200 mg Tramadol Contramid®                                                                       • The overall extent of exposure to tramadol is bioequivalent between tramadol ER and tramadol IR following single- and
studies. Both the single-dose and multiple-dose studies had an open-label, randomized, 2-way crossover                                                          administration of 200 mg Tramadol Contramid® OAD tablets and 50 mg                                                                                                              OAD tablets and 50 mg tramadol IR tablets for 5 days                                                                                            multiple-dose administration.(10,11)
design. Twenty-six healthy adult subjects were enrolled in each study. All subjects completed the multiple-                                                     tramadol IR tablets                                                                                                                                                                                                                                                                                                           • Tramadol ER exhibits a lag time of approximately 2 hours during which no appreciable drug absorption occurs, and
dose study and 24 subjects completed the single-dose study. In both studies, Tramadol Contramid® OAD was                                                                                                                                                                                                                                                                                 500                                                                                                    maximum plasma levels are attained >10 hours post-dose.(10,11)
                                                                                                                                                                                                               500                                                 ®
administered orally as a 200 mg tablet dose once daily and tramadol IR was administered as one 50 mg tablet                                                                                                                            Tramadol Contramid OAD 200 mg tablet x 1 dose                                                                                                                                                                                                          • Following single-dose administration of tramadol ER, minimum effective plasma levels (>100 ng/mL) are not attained
                                                                                                                                                                                                                                       Tramadol IR 50 mg tablet q6h x 4 doses




                                                                                                                                                                                                                                                                                                                                                        Tramadol Concentration (ng/mL)
every 6 hours. In the multiple-dose study, each treatment was administered for five consecutive days. Plasma                                                                                                                                                                                                                                                                                                                                                                                    until approximately 6 hours post-dose.(11)




                                                                                                                                                                              Tramadol Concentration (ng/mL)
tramadol and O-desmethyltramadol levels were determined using validated LC/MS/MS methods. Primary                                                                                                              400
                                                                                                                                                                                                                                                                                                                                                                                         400                                                                                                  • Mean steady-state concentrations for tramadol ER are maintained above the lowest mean concentration attained for
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                tramadol IR for approximately 70% of the dosing interval.(10)
pharmacokinetic parameters [single-dose: AUC0-t, AUC0-inf and Cmax; steady-state: AUC0-24 and Cmax] were
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              • Steady state is attained within 4 days for tramadol ER.(10)
assessed by ANOVA. In both studies, the AUC parameters met bioequivalence criteria (90% CI within                                                                                                                                                                                                                                                                                        300
                                                                                                                                                                                                               300
80-125%) and the Cmax of Tramadol Contramid® OAD was lower than that of tramadol IR. Following single-
dose administration, the mean tramadol concentrations at 1 hour post-dose were within the therapeutic range
                                                                                                                                                                                                                                                                                                                                                                                         200
(100-300 ng/mL). Steady-state concentrations were attained within 48 hours following the first dose of                                                                                                         200

Tramadol Contramid® OAD. Peak-to-trough variation was 77% for Tramadol Contramid® OAD, compared with
                                                                                                                                                                                                                                                                                                                                                                                                                                                     Minimum therapeutic level
91% for tramadol IR. Tramadol Contramid® OAD 200 mg achieves therapeutic plasma concentrations within                                                                                                                                                                      Minimum therapeutic level                                                                                     100                                                                                                 CONCLUSIONS
                                                                                                                                                                                                               100
                                                                                                                                                                                                                                                                                                                                                                                                                       ®
1 hour of administering the first dose and remains above the minimum therapeutic concentration (>100 ng/mL)                                                                                                                                                                                                                                                                                        Tramadol Contramid OAD 200 mg tablet QD
                                                                                                                                                                                                                                                                                                                                                                                                   Tramadol IR 50 mg tablet QID q6h                                                          • Tramadol Contramid® OAD 200 mg tablets provide equivalent exposure
for 24 hours; exposure is equivalent to tramadol IR 50 mg every 6 hours with respect to AUC, with a lower
Cmax.                                                                                                                                                                                                           0
                                                                                                                                                                                                                                                                                                                                                                                           0
                                                                                                                                                                                                                                                                                                                                                                                               0      4            8           12                   16               20                 24
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               compared with tramadol IR tablets (Ultram®) following both single- and
                                                                                                                                                                                                                     0   4   8   12      16        20     24
                                                                                                                                                                                                                                                        Time (h)
                                                                                                                                                                                                                                                                   28       32       36   40     44     48
                                                                                                                                                                                                                                                                                                                                                                                                                             Time (h)                                                          multiple-dose administration.
INTRODUCTION                                                                                                                                                                                                                                                                                                                   • Both products were well tolerated.                                                                                                                          • Following single- and multiple-dose administration, Cmax for Tramadol
                                                                                                                                                • Both products were well tolerated.
Tramadol is a centrally acting, synthetic analgesic used in the management of pain.(1) Tramadol and its M1 metabolite,                          • The 90% confidence intervals for AUC0-t, AUC0-24, AUC0-∞ were within the 80-125% range (Table 1). Thus, Tramadol Contramid®
                                                                                                                                                                                                                                                                                                                               • Analysis of trough concentrations on Days 3, 4 and 5 showed no statistically significant differences for either Tramadol Contramid®
                                                                                                                                                                                                                                                                                                                                 OAD 200 mg or tramadol IR 50 mg. Thus, steady state was attained within 48 h for both products.
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               Contramid® OAD 200 mg is lower than that for tramadol IR 50 mg.
O-desmethyltramadol, act as opioid agonists through selective binding to the µ-opioid receptor and weak inhibition of norepinephrine              OAD 200 mg is bioequivalent to tramadol IR 50 mg with respect to extent of exposure.
                                                                                                                                                                                                                                                                                                                               • The 90% confidence interval for AUCss was within 80-125% (Table 2). Therefore, bioequivalence with respect to extent of exposure
and serotonin re-uptake.(2-4) This second mode of action is thought to complement opioid receptor binding, thereby increasing                   • Cmax was lower for Tramadol Contramid® OAD 200 mg compared with tramadol IR 50 mg.
                                                                                                                                                • The mean tramadol concentration remained above 100 ng/mL 24 hours after a single dose of Tramadol Contramid® OAD 200 mg.
                                                                                                                                                                                                                                                                                                                                 was concluded.                                                                                                                                              • Following single-dose administration, the initial absorption of tramadol
analgesic activity.(5) Since tramadol has a relatively short half-life, immediate-release formulations must be administered at least four                                                                                                                                                                                      • Cmax was lower for Tramadol Contramid® OAD 200 mg compared with tramadol IR 50 mg.
times a day. In general, dosing frequency has been shown to be inversely proportional to compliance.(6,7) The lack of compliance
                                                                                                                                                • The mean tramadol plasma concentrations at 1 hour post-dose were within the therapeutic range (100-300 ng/mL): 110 ± 40 ng/mL
                                                                                                                                                                                                                                                                                                                               • Tramadol Contramid® OAD 200 mg had less peak-to-trough variability than tramadol IR 50 mg.                                                                    from Tramadol Contramid® OAD 200 mg is rapid (comparable to
                                                                                                                                                  for Tramadol Contramid® OAD 200 mg and 158 ± 54 ng/mL for tramadol IR 50 mg.
associated with high-frequency dosing regimens can result in inconsistent plasma drug concentrations and, accordingly, less                     • Similar results were obtained for the metabolite (results not shown).
                                                                                                                                                                                                                                                                                                                               • Mean steady-state tramadol concentrations for Tramadol Contramid® OAD 200 mg were maintained above the lowest mean
                                                                                                                                                                                                                                                                                                                                 concentration attained for tramadol IR 50 mg for 83% of the dosing interval.
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               Tramadol IR 50 mg).
consistent analgesia. Modified-release formulations have the potential to improve patient compliance by simplifying the dosing
                                                                                                                                                                                                                                                                                                                               • Similar results were obtained for the metabolite (results not shown).
regimen. However, the rate of drug release from modified-release formulations is generally slower than for immediate-release
formulations. A novel once-daily tramadol formulation recently developed by Labopharm Inc. uses Contramid® technology that is
                                                                                                                                                            Table 1. Mean (±SD) tramadol single-dose pharmacokinetic parameters and results                                                                                                                                                                                                                                                  • Effective plasma concentrations are attained within 1 h of dosing and
                                                                                                                                                            of comparison [n=24]
based on chemically cross-linked high-amylose starch. Using a dual matrix delivery system, Tramadol Contramid® OAD tablets were                                                                                                                                                                                                                   Table 2. Mean (±SD) steady-state tramadol pharmacokinetic parameters                                                                         maintained for a full 24-h post-dose period following single-dose
designed to attain therapeutic levels (>100 ng/mL)(8) within 2 hours and provide continuous drug delivery and corresponding pain                                                                                                                                                                                                                  and results of comparison [n=26]
relief over 24 hours following a single dose, and to provide steady-state levels between 100 and 300 ng/mL with a once-daily dosing
                                                                                                                                                                                                                                         Tramadol
                                                                                                                                                                                                                                               ®
                                                                                                                                                                                                                                      Contramid OAD                     Tramadol IR
                                                                                                                                                                                                                                                                                                      Ratio of
                                                                                                                                                                                                                                                                                               Least-Squares Means
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               administration of Tramadol Contramid® OAD 200 mg.
                                                                                                                                                                        PK Parameter                                                   200 mg tablet                    50 mg tablet                 (90% CI)
regimen. Three strengths were developed: 100 mg, 200 mg and 300 mg. Comparative bioavailability studies were conducted to                                                                                                                                                                                                                                                                                      Tramadol                                               Ratio of
evaluate the performance of the 200 mg tablets following single-dose and multiple-dose administration.
                                                                                                                                                                        AUC0-t (ng·h/mL)
                                                                                                                                                                        AUC0-24 (ng·h/mL)
                                                                                                                                                                                                                                       5582 ± 2535
                                                                                                                                                                                                                                       4382 ± 1812
                                                                                                                                                                                                                                                                        5851 ± 2456
                                                                                                                                                                                                                                                                        4429 ± 1620
                                                                                                                                                                                                                                                                                                92.8 (87.2 – 98.7)
                                                                                                                                                                                                                                                                                                96.0 (90.5 – 101.8)                                    PK Parameter
                                                                                                                                                                                                                                                                                                                                                                                                                     ®
                                                                                                                                                                                                                                                                                                                                                                                                            Contramid OAD
                                                                                                                                                                                                                                                                                                                                                                                                             200 mg tablet
                                                                                                                                                                                                                                                                                                                                                                                                                                     Tramadol IR
                                                                                                                                                                                                                                                                                                                                                                                                                                     50 mg tablet
                                                                                                                                                                                                                                                                                                                                                                                                                                                               Least-Squares Means
                                                                                                                                                                                                                                                                                                                                                                                                                                                                     (90% CI)
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             • Steady state is attained within 48 h following initiation of dosing with
OBJECTIVES                                                                                                                                                              AUC0-∞ (ng·h/mL)                                               5748 ± 2661                      6008 ± 2607             93.1 (87.5 – 99.2)
                                                                                                                                                                                                                                                                                                                                                       AUCss (ng·h/mL)
                                                                                                                                                                                                                                                                                                                                                       Cmax (ng/mL)
                                                                                                                                                                                                                                                                                                                                                                                                              5991 ± 1330
                                                                                                                                                                                                                                                                                                                                                                                                               345 ± 73
                                                                                                                                                                                                                                                                                                                                                                                                                                     6399 ± 1766
                                                                                                                                                                                                                                                                                                                                                                                                                                       423 ± 97
                                                                                                                                                                                                                                                                                                                                                                                                                                                                 94.7 (91.1 – 98.5)
                                                                                                                                                                                                                                                                                                                                                                                                                                                                 81.8 (77.5 – 86.3)
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               Tramadol Contramid® OAD 200 mg, allowing for titration up to the
                                                                                                                                                                        AUCRefTmax (ng·h/mL)                                            111 ± 112                         122 ± 82              74.5 (63.4 – 87.6)
  • Compare the single-dose bioavailability of Tramadol Contramid® OAD (Labopharm Inc.) 200 mg tablets with tramadol IR
    (Ultram®) (Ortho-McNeil Pharmaceutical Inc.) 50 mg tablets administered 4 times at 6-hour intervals.
                                                                                                                                                                        Cmax (ng/mL)                                                     256 ± 90                        353 ± 118              71.6 (66.9 – 76.7)                                     Cmin (ng/mL)                                            157 ± 48                190 ± 64                  83.4 (78.7 – 88.4)            higher doses on the third day.
                                                                                                                                                                        CRefTmax (ng/mL)                                                 127 ± 53                         190 ± 53              62.6 (52.9 – 74.0)                                     PTF (%)                                                76.9 ± 20.0             91.1 ± 20.0                83.1 (75.2 – 91.9)
  • Assess the relative bioavailability of Tramadol Contramid® OAD 200 mg tablets and tramadol IR 50 mg tablets at steady state.                                        t½ (h)                                                          7.07 ± 1.42                      6.03 ± 1.31           117.6 (111.8 – 123.7)                                   HVD (h)                                                 20.7 ± 2.6              22.0 ± 2.2                94.0 (90.1 – 98.0)
                                                                                                                                                                                -1
                                                                                                                                                                                                                                       0.102 ± 0.020                    0.120 ± 0.027                                                                  Tmax (h) #                                              4 (3 – 9)                1 (1 – 3)
                                                                                                                                                                        λz (h )
METHODOLOGY                                                                                                                                                                                                                                                                                                                                            AUCss, area under the concentration-time curve over dosing interval at steady state; Cmax, maximum concentration; Cmin, minimum
                                                                                                                                                                        Tmax (h) #                                                      6 (2.5 – 16)                    16 (6.5 – 20)
                                                                                                                                                                                                                                                                                                                                                       concentration; PTF, peak-to-trough fluctuation (calculated as %PTF = 100 * (Cmax – Cmin)/AUCss/24 h); HVD, half value duration
Both studies were conducted in compliance with ICH GCP guidelines and in accordance with the Declaration of Helsinki. Study                                             RefTmax (h) #                                                          -                       1.25 (0.5 – 3.0)                                                                (obtained by linear interpolation between the respective concentrations above and below 50% of Cmax); Tmax, time to reach maximum
protocols were approved by an independent ethics committee. The nature of each study was explained and subjects provided their                                          C0.25h (h)                                                      1.17 ± 2.49                      3.02 ± 6.46                                                                   concentration.                                                                                                                        REFERENCES
written consent before any study-related procedures were performed.                                                                                                     C0.50h (h)                                                      55.3 ± 33.1                      64.5 ± 67.5                                                                   # median values and range presented.
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             1)  Scott LJ, Perry CM. Tramadol: a review of its use in perioperative pain. Drugs. 2000; 60: 139-76.
                                                                                                                                                                       AUC0-t, AUC0-24 and AUC0-∞, area under the plasma concentration time curve from time 0 to last observed concentration, to 24 h and
Single-dose comparison                                                                                                                                                 extrapolated to infinity, respectively; AUCRefTmax, area under the plasma concentration time curve from time 0 to RefTmax (where                                                                                                                                                                                      2)  Raffa RB, Friderichs E, Reimann W, Shank RP, Codd EE, Vaught JL. Opioid and nonopioid components independently
This study had an open-label, randomized, two-way crossover design. A total of 26 healthy volunteers (22 males and 4 females) were
                                                                                                                                                                       RefTmax is time corresponding to the maximum concentration of the tramadol IR product following the initial dose (0-6 h)); Cmax,
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 contribute to the mechanism of action of tramadol, an 'atypical' opioid analgesic. J Pharmacol Exp Ther 1992; 260:
                                                                                                                                                                       maximum concentration; CRefTmax, observed concentration at RefTmax; t½, apparent terminal elimination half-life; λz, apparent
enrolled. Two subjects discontinued from the study: one as a result of an adverse event (vomiting) after receiving the tramadol IR                                     terminal elimination rate constant; Tmax, time to maximum concentration; Cnh, mean tramadol plasma concentration at n hours post-dose.                                                                                                                                                                                    275-85.
product, and one because of a protocol violation. Thus, 24 subjects (21 males and 3 females) completed the study. In each study                                        # median values and range presented.
                                                                                                                                                                                                                                                                                                                               DISCUSSION                                                                                                                                                    3) Raffa RB, Friderichs E, Reimann W, Shank RP, Codd EE, Vaught JL, Jacoby HI, Selve N. Complementary and
period, following an overnight fast, subjects received either a single 200 mg Tramadol Contramid® OAD tablet dose or a 50 mg                                                                                                                                                                                                   Tramadol Contramid® OAD tablets were designed to provide both an immediate initial release of tramadol for rapid onset of                                         synergistic antinociceptive interaction between the enantiomers of tramadol. J Pharmacol Exp Ther 1993; 267: 331-40.
tramadol IR tablet dose 4 times at 6-hour intervals, according to the randomization scheme. Each dose was administered with
                                                                                                                                                                                                                                                                                                                               analgesia, followed by controlled release of tramadol to provide analgesia over a full 24 hours after dosing. The analgesic                                   4) Valle M, Garrido MJ, Pavon JM, Calvo R, Troconiz IF. Pharmacokinetic-pharmacodynamic modeling of the
240 mL of water. A washout period of at least 6 days separated the last dose in Period 1 and the first dose in Period 2. Blood samples
                                                                                                                                                                Figure 2. Mean (SD) plasma tramadol concentrations over the first                                                                                              efficacy of Tramadol Contramid® OAD tablets in patients with osteoarthritis has been demonstrated previously.(9)                                                  antinociceptive effects of main active metabolites of tramadol, (+)-O-desmethyltramadol and (-)-O-desmethyltramadol,
were collected pre-dose and at 0.25, 0.5, 0.75, 1, 1.25, 1.5, 2, 2.5, 3, 4, 5, 6, 9, 12, 16, 20, 24, 30, 36 and 48 h post-dose for
Tramadol Contramid® OAD and pre-dose and at 0.25, 0.5, 0.75, 1, 1.25, 1.5, 2, 2.5, 3, 4, 6*, 6.5, 7, 7.5, 8, 8.5, 9, 10, 12*, 12.5, 13,                                                                                                                                                                                        Mean plasma tramadol concentrations at 0.25 and 0.50 hours post-dose were similar for Tramadol Contramid® OAD and for                                             in rats. J Pharmacol Exp Ther 2000; 293: 646-53.
                                                                                                                                                                6 hours following single-dose administration of 200 mg Tramadol Contramid®
13.5, 14, 14.5, 15, 16, 18*, 18.5, 19, 19.5, 20, 20.5, 21, 22, 24, 30, 36 and 48 h post-dose for the tramadol IR product. Plasma                                                                                                                                                                                               tramadol IR. This suggests that tramadol absorption from both products starts at approximately the same time.                                                 5) Aronson MD. Nonsteroidal anti-inflammatory drugs, traditional opioids, and tramadol: contrasting therapies for the
samples were assayed using a validated LC/MS/MS method (LLOQ: tramadol, 2.91 ng/mL; O-desmethyltramadol, 0.806 ng/mL).
                                                                                                                                                                OAD tablets and 50 mg tramadol IR tablets
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 treatment of chronic pain. Clin Ther 1997; 19: 420-32.
Pharmacokinetic parameters were calculated using noncompartmental methods. Values of PK parameters were compared using                                                                                                                                                                                                         Tramadol Contramid® OAD exhibits a plasma concentration-time profile with a steep initial slope comparable to immediate-
                                                                                                                                                                                                               400                                                                                                             release tramadol tablets, suggesting a rapid attainment of therapeutic concentrations. Immediate-release tramadol has                                         6) Claxton AJ, Cramer J, Pierce C. A systematic review of the associations between dose regimens and medication
ANOVA following log-transformation of the data (α = 5%). The mean square error from this ANOVA was used to construct the                                                                                                                 Tramadol Contramid® OAD 200 mg tablet x 1 dose
                                                                                                                                                                                                                                                                                                                               shown analgesic effects within 1 hour of dosing with similar tramadol plasma concentrations as those measured for the                                             compliance. Clin Ther 2001; 23: 1296-1310.
conventional confidence intervals. Bioequivalence was concluded if the 90% confidence interval for the Tramadol Contramid®                                                                                                               Tramadol IR 50 mg tablet x 1 dose
OAD/tramadol IR ratio of geometric means for AUC0-t and AUC0-∞ fell within the conventional range of 80% to 125%.                                                                                                                                                                                                              Tramadol Contramid® OAD within the same time frame.                                                                                                           7) Kruse W, Eggert-Kruse W, Rampmaier J, Runnebaum B, Weber E. Dosage frequency and drug-compliance behaviour
                                                                                                                                                                             Tramadol Concentration (ng/mL)




*Blood sample collected immediately prior to the dose                                                                                                                                                                                                                                                                                                                                                                                                                                            – a comparative study on compliance with a medication to be taken twice or four times daily. Eur J Clin Pharmacol
                                                                                                                                                                                                               300                                                                                                             Two parameters, AUCRefTmax and CRefTmax, were calculated to compare the initial absorption phases following single-dose                                           1991; 41: 589-592.
Multiple-dose comparison                                                                                                                                                                                                                                                                                                       administration of the two tramadol products. The mean tramadol concentration following dosing with Tramadol Contramid®
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             8) Topalgic LP (Tramadol) Monograph, Dictionnaire Vidal, ed. 2004: pp. 1948-9.
In this study, which had an open-label, randomized, 2-way crossover design, 26 healthy volunteers (22 males and 4 females)                                                                                                                                                                                                     OAD 200 mg is 63% that of tramadol IR 50 mg at RefTmax. However, the AUC of Tramadol Contramid® OAD 200 mg is
                                                                                                                                                                                                                                                                                                                               approximately 75% that of tramadol IR 50 mg at that same timepoint. Thus tramadol exposure over the initial hours                                             9) Mongin G, Yakusevich V, Köpe A, Shostak N, Pikhlak E, Efficacy and safety assessment of a novel once-daily tablet
received a 200 mg Tramadol Contramid® OAD tablet once daily for 5 days or a 50 mg tramadol IR tablet every 6 hours for 5 days.
                                                                                                                                                                                                                                                                                                                               following single-dose administration is similar for the two products. This is supported by the observation that the minimum                                       formulation of tramadol. Clin Drug Invest 2004; 24: 545-58.
Trough concentrations, measured prior to the morning dose on Days 3, 4 and 5, were used to confirm that steady state had been                                                                                  200
attained. Each dose was administered with 240 mL of water, the morning dose following an overnight fast. In each period, subjects                                                                                                                                                                                              therapeutic tramadol concentration (>100 ng/mL) is attained within 1 h for both products.                                                                     10) Ultram® ER (tramadol) Prescribing Information, January 2006.
received the assigned formulation according to the randomization scheme. Treatment periods were separated by a 16-day washout
                                                                                                                                                                                                                                                                                                                               The mean tramadol concentration remains above 100 ng/mL 24 hours after a single dose of Tramadol Contramid® OAD 200                                           11) Lai JC, Sista S, Eradiri O, The pharmacokinetics of novel once daily tramadol hydrochloride extended release tablets in
period. On the profile day, blood samples were collected pre-dose and at 1, 2, 3, 4, 5, 6, 9, 12, 16, 20 and 24 h post-dose for the test                                                                                                                                                                                                                                                                                                                                                         healthy subjects. Poster presented at AAPS Annual Meeting 2003, Salt Lake City, Utah.
product and pre-dose and at 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6*, 6.5, 7, 7.5, 8, 8.5, 9, 10, 11, 12*, 12.5, 13, 13.5, 14, 14.5, 15, 16, 17, 18*,                                                                  100                                                                                                             mg. The therapeutic effect over the full 24 hour dosing interval has been previously demonstrated in a clinical study.(9)
                                                                                                                                                                                                                             Minimum therapeutic level
18.5, 19, 19.5, 20, 20.5, 21, 22, 23 and 24 h post-dose for the tramadol IR product. Plasma samples were assayed using a validated                                                                                                                                                                                             Steady state is attained within 2 days following once-daily administration of Tramadol Contramid® OAD 200 mg. Therefore,
LC/MS/MS method (LLOQ: tramadol, 0.776 ng/mL; O-desmethyltramadol, 0.790 ng/mL). Pharmacokinetic parameters were                                                                                                                                                                                                               it is possible that patients may be titrated to their optimum dose within 48 hours (which is comparable to the immediate
calculated using noncompartmental methods. Values of PK parameters were compared using ANOVA following log-transformation of                                                                                                                                                                                                   release formulation).
the data (α = 5%). Bioequivalence was concluded if the 90% confidence interval for the Tramadol Contramid® OAD/tramadol IR ratio                                                                                 0
of geometric means for AUCss fell within the conventional range of 80% to 125%.                                                                                                                                      0       1             2                3                 4            5               6                   Since the two tramadol formulations are bioequivalent in terms of extent of exposure at steady state, this will facilitate the                                ACKNOWLEDGEMENTS
*Blood sample collected immediately prior to the dose                                                                                                                                                                                                   Time (h)                                                               switch from tramadol IR 50 mg to Tramadol Contramid® OAD 200 mg.
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             The authors are grateful to the staff at FARMOVS-PAREXEL, Bloemfontein, South Africa, for their assistance in
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             the planning and conduct of these studies. This research was funded by Labopharm Inc.