What is rational prescribing

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					Rational Prescribing

                       ~ Dr PL Lau
What is rational prescribing?

   Maximizing effectiveness
   Minimizing risk
   Minimizing cost, and
   Respecting patient choice
Six "rights" of prescribing

   the right diagnosis
   the right drug
   the right dose
   the right route
   the right patient
   the right time
Process of decision making

   not all aspects of this decision are pharmacological
   one shouldn't underestimate the importance of
    history, examination, and diagnosis as part of the

   This process of decision making is not static and will
    need to be adapted to take into account the various
    different factors for individual patients, often
    requiring a different answer for different reasons in
    different situations
Process of decision making

   Decisions will not always be clear cut
   Utilise the concept of the benefit : harm ratio
    in reaching the most appropriate conclusion
Process of decision making

   Necessary information may not always be
    readily available, we need to consider:
       Seriousness of the diagnosis
       Drug efficacy
       Seriousness and frequency of potential adverse
       Safety and efficacy of alternative treatments
Components of rational prescribing

   Evidence
       Reliability (gold standard is RCT, systematic reviews)
       Availability
       number needed to treat/harm (NNT/NNH)
   Alternatives and their efficacy
       Same class, different class
       different modality (eg, physiotherapy, occupational therapy,
        alternative therapies)
   Contraindications
       Hypersensitivity, children, elderly, pregnancy, breast
        feeding, liver or renal impairment
   Drug interaction
       Similar mechanism of action or adverse effects
       enzyme inducers or inhibitors
       narrow therapeutic window
       Pharmacokinetics
   Optimal dose and duration
       Pharmacokinetics, route, patient weight or body surface
        area, drug half life, calculation errors (correct units)
   Formulation or route
       Target site, speed of onset, bioavailability
       dosing frequency
       patient acceptability
   Compliance
       Polypharmacy
       dosing frequency
       potential adverse effects
       patient ability, patient beliefs, adequate counselling
   Adverse drug reactions
       Interpretation and communication of risk to patients
   Monitoring
       Objective or subjective, efficacy (symptoms, disease
        markers, blood levels), toxicity
   Availability
       Cost (generic v branded), formularies
Why do we prescribe?
   need to have a therapeutic aim in mind !

   Alleviating symptoms
   Replacing deficiencies
   Preventing disease
   Curing disease

   Prescribers may have tactical reasons for prescribing:
       To buy time while waiting for another intervention
       To monitor a patient's condition when they present for their repeat
       For a therapeutic trial to help diagnosis
       To respond to patients' expectations and maintain the doctor-patient
Irrational prescribing

   Rarely intentional and often arises by default
   for example
       a diagnosis is found to be incorrect but the
        treatment is not discontinued
       additional treatment is started to treat the adverse
        effects of another drug
       doses not correctly titrated, resulting in
        overdosage or underdosage
Common scenario

   A case of URTI
       A 25 years old previous healthy lady was
        diagnosed to have URTI, drug given by previous
        doctor include
              Prednisolone 5mg TDS
              Ciprofloxacin 250mg daily
              Piriton 4mg TDS
              Codeine phosphate 30mg TDS
              Phensedyl 10ml TDS
   Cough commonly secondary to postnasal drip or inflammation of
    the pharynx
   Antihistamines that reduce nasal discharge may already control
    the cough without need of additional medications

   Cough mixtures contain one or a combination of substances
    ranging from simple syrup or potent drug such as opioid
   Opioid derivatives, including codeine have only been shown to
    be more effective in suppressing pathological chronic cough, are
    not superior to simple syrup in reducing cough associated with
   Clinical trials failed to show any effectiveness from
    mucolytics/expectorants in the relief of cough associated with
Nasal symptoms

   Antihistamines and alpha adrenergic agonists are
    most commonly used
   Systemic non-selective antihistamines have been
    shown to reduce symptoms of sneezing and nasal
   Effect of selective non-sedating antihistamines are

   Majority of URTI are self-limiting viral infection
   2 systematic reviews on a total of 19 trials
       failed to show any beneficial effect from antibiotics for the
        cure or symptomatic relief of the common cold
   Antibiotics
       increase the cure rate of rhinosinusitis characterized by
        persistent nasal discharge in children
       shorten duration of pharygitis by 1-2 days for patients with
        culture-positive group A beta hemolytic Strep

   Choice of antibiotics should be guided by
    epidemiology data on likely pathogen
   Group A Strep
       most likely bacteria for pharyngitis
       Pen V is the most rational choice as most are sensitive to
        penicillin, erythromycin alternative but 22% resistant
   Quinolones should be reserved for infections not
    cure by the above antibiotics as they are more
    broad spectrum and overuse lead to increase
    resistance rate
Patient expectations

   23% of people did not always expect drug from a
   78% disagreed that more drugs were better and 7%
    said doctors gave them too many drugs

   For URTI problem, 91% expected medications from
    a consultation for URTI, 57% said they would accept
    no medication if doctor explained none was
Scenario 2

   70/M with Hx of Degenerative spine, gout, HT, DM,
    AF, IHD with PCI, BPH, # Rt hip with AMA, chronic
   FU today in GOPC
   Also c.o URTI x 1/52 with RN, cough, dry mouth,
    sorethroat, malaise, fever 38.1C
   Exam: unremarkable
   Seen twice in GOPC treated as URTI given Rx by
    GOPC Dr. but no improvement after medication
Medication list

   Aspirin 80mg QD              Triact 1 tab QID PRN
   Digoxin 62.5mcg QD           Analgesic Balm LA tds PRN
   Moduretic 1 tab OM           Aqueous Cr LA TDS PRN
   Adalat R 40mg BD             Neozep 1 tab TDS PRN
   Acertil 4mg QD               Piriton 4mg TDS PRN
   Minipress 2mg BD             Bisolvon 8mg TDS PRN
   Allopurinol 100mg QD         Panadol 500mg QID PRN
   Senokot 2 tab nocte          Phensedyl 10mg TDS PRN
   Dologesic 1 tab QID PRN

   Neozep contains :
       Phenylpropanolamine 25mg
       Piriton 2mg
       Panadol 150mg
   Neozep+Piriton+phensedyl = antihistamine OD!
   Dologesic also contains:
       320mg Acetaminophen
   Pandaol + Dologesic + Neozep = Panadol OD!!

   BPH +Antihistamine = AROU!!
   Allopurinol for Gout
       Effective dose of allopurinol should be 300mg
        qd(for pts with normal RFT)
   Constipation secondary to Adalat R

   Moduretic + Acertil
       Moduretic contains amiloride 5mg +
        hydrochlorothizide 50mg
       diuretics potentiate ACEI-induced ARF
           retrospective study compared ACEI alone vs
            combination of an ACEI and a diuretic
           A highly significant group difference (P < .001) in ARF in
            2.4% of Group ACEI alone vs 33% of combination group
           Ref. Clin Nephrol. 1994;42:170-174.

   K-sparing Diuretics + ACEI
       concomitant use of an ACEI or an ARB and a
        potassium-sparing diuretic may cause additive,
        and in some cases life-threatening, hyperkalemia
Dispensing Error
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      本港首宗配錯藥奪命案的李世澧事件,李

Dispensing Error

   UK study in 89 hospital from 1991 to 2001, 7158
    error reports (an error which is detected and
       34% inpatient
       28% discharge medicines
       20% for outpatient medicines
       14% for other uses
   Errors detected by:
       nurses (45%)
       hospital pharmacists (17%)
       patients(17%)
       other hospital staff (21%)
UK experience

   The most common errors
       supply of the wrong medicine (23%),
       wrong strength of the prescribed medicine (23%)
       the wrong directions for use (10%)
       Wrong quantity of medicine (10%)
   Factors contributing to errors
       „look alike‟ and „sound alike‟ medicines(33%)
       high workload and/or low staffing (23%)
       inexperienced staff (20%)
       transcription (14%)
       other causes (10%)
UK experience

   Recorded outcomes
       one fatality (0.02%)
       Serious detrimental effects (0.08%)
       moderate detrimental effects (6.6%)
       no/minor detrimental effects (92.5%)
UK experience

   prospective study where pharmacists
    recorded all dispensing error incidents over a
    4 week period in 35 community pharmacies
   dispensing error rate of 40 errors per 100,000
    items dispensed.
       Product selection errors (60.3%)
       labelling (33%)
       bagging errors (6.6%)
UK experience

   Incidences were caused by
       misreading the prescription (24.5%)
       similar drug names (16.8%)
       selecting the previous drug or dose from the
        medication record on the pharmacy computer
        (11.4%) or similar packaging (7.6%)
UK experience

   Chua et al in 2003
   Error rate in community pharmacies at 0.08%, and
    0.48% near misses
   near misses occur six times more often than actual
    dispensing errors
   importance of a double check by a second person

         Ref: Safer Health Care BMJ -NHS
Murphy’s Law
  Anything that can go wrong, will go wrong.
Why do prescription errors occur?

   Unfamiliar work environment
   High workload
   Whether clinicians are prescribing for their
    own patients
   Poor team communication
   Poor physical and mental well being
   Lack of Knowledge
High risk prescribing moments

   Amendment
   More than one record
   Diverting your attention
   “High risk" drugs –e.g. anticoagulants,
    opioids, and sedatives
   Rushing
   Unfamiliar drugs
High risk prescribing moments

   Transcribing prescriptions
   prescriptions based on information from
    another source e.g. referral letter
   Miscalculating drug doses accounts for up to
    20% of prescribing errors
   drugs that sound or look alike-for example,
    chlorphenamine and chlorpromazine
Careful Prescriptions

   Block capitals, legibly
   Identifying details, e.g. patient's name,
    hospital number, date of birth, and age
   Look at the drug sensitivities or allergies
   Use generic drug names rather than brand
Careful Prescriptions

   “Units”
   Avoid decimal points
   Dose frequency
   Route of administration
   Advice on administration
   Knowledge
   Forgot all already?

   Barber N. What constitutes good prescribing? BMJ 1995;310:923-5
   Jamie J Coleman. The medic's guide to prescribing: Rational
    prescribing. StudentBMJ
   CLK Lam. Rational prescribing for upper respiratory tract infections
    HK practitioner 2002
   What do patients expect from consultations for upper respiratory
    tract infections? Fam Pract 1996; 13: 229-235
   Adnan Beso et al. The Frequency and Potential Causes of Dispensing
    Errors in a Hospital Pharmacy. Pharmacy World & Science 27:3 928-