LAXATIVES
CLASS DRUG PHARMACODYNAMIC PHARMACOKINETIC THERAPEUTIC USES SIDE EFFECTS NOTES
MODE OF ACTION
1)BULK FORMING -Psyllium (nat, non- -absorb H2O enlarge in -powder form(taken with -simple constipation -can cause flatus & -simplest, safest
AGENTS absorbable fiber) size stretch intestinal H2O) -elderly pt w/out cramps( because of -non-absorbable,
wall Stimulate peristalsis intestinal obstruction bacterial degradation) hydrophilic colloids
-Methylcellulose(semi- Increase fecal volume, -hemorrhoids pt -if not taken with -effect requires few
synthetic) transit rate & soften stool -pt with anal fissure plenty of H2O, cause days
-pt with intestinal intestinal obstruction -given in small amount
-Polycarbophil (synthetic) diverticula -loss of H2O &
electrolytes imbalance
-interfere absorption
of other drugs(
transit rate causing no
enough time for
absorption)
2)OSMOTIC a)Saline osmotic: -hyperosmotic solutions -orally(evacuate whole -2nd line therapy in pt x -dehydration -dose preparation
LAXATIVES Absorb H2O enlarge in intestine) responding to bulk -electrolyte dependant
-MgOH size stretch intestinal -rectally(evacuate lower agents imbalance: a)Large dose of
-Mg Citrate wall stimulate peristalsis part) -endoscopic Hyperphosphatemia, NaPO4(complete
-MgSO4 *rectal route have more examinations hypernatremia, evacuation in 1-3hrs-
-NaPO4 advantage(suppository -termination of toxins hypokalemia, cathartic effect)
produce CO2 increase -removal of fecal hypocalcemia, cardiac b)Small dose of
intestinal stretch) impaction in elderly arrhythmia, acute MgOH(req few days to
renal failure, show effect-laxative
nephrocalcinosis effect)
b)Sugar osmotic -can’t be affected by -synthetic disaccharide
-lactulose disaccharides in intestine, preparation
most reaches colon (galactose+fructose)
-in colon, bact degrades & -prevention of portal-
liberate fructose + galactose ecephalopathy(in pt
+ acids(lactic, acetic, formic) with hepatic
Draw H2O, lower pH coma/hepatic failure
Inhibit ammonia-forming
bact
leave with feces(x in liver)
Copyright: Aliaa Mohd Radzi aleeya_nlr@yahoo.com
CLASS DRUG PHARMACODYNAMIC PHARMACOKINETIC THERAPEUTIC USES SIDE EFFECTS NOTES
MODE OF ACTION
c)Polyethylene Glycol -complete evacuation of -very popular, non-
GIT absorbable, iso-
-endoscopy, osmotic, non-toxic
segmoidoscopy (pt drink -mixed with Na
4L wthn 3-4hrs) bicarbonate, NaCl,
NaSO4, KCl
3.STIMULANT (formerly known as irritant -direct stimulation of nerve -severe constipation -H2O and electrolyte
LAXATIVES purgatives) plexus in intestines imbalance
-increase intestinal secretion -nutrition deficiency
by inducing mild -can cause colonic
inflammation of intestinal wal atony&inertia if used in
longer duration
-Bisacodyl -orally(6-8hrs) -abdominal cramps and
-rectally(1-2hrs) pain
-enema prepation
cause hepatic toxicity
-Anthraquinones(aloe, -contain active ingredient, a -enter milk of nursing -better effect than
cascara, senna) non absorbable compound mothers: melanosis coli bisacodyl
reach the intestine (brown colour
stimulating intestinal nerves pigmentation of wall of
intestine)
-Castor oil -converted into ricinoleic -used before taking -abdominal cramps -contraindicated during
acid(very irritant to small abdominal x-ray -uterine contraction in breast feeding
intestine) -(long time ago) used in pregnant -pt taking this oil
pregnant ladies for: ladies(abortion) should wait few days to
1)evauate colon accumulate new amnt
facilitating clean delivery of intestinal contents
2)induce delivery by
stimulating uterine
contraction
Copyright: Aliaa Mohd Radzi aleeya_nlr@yahoo.com
CLASS DRUG PHARMACODYNAMIC PHARMACOKINETIC THERAPEUTIC USES SIDE EFFECTS NOTES
MODE OF ACTION
4. SURFACTANT (mineral oil&liquid -lubricating intestinal wall
SOFTENERS paraffin)
-Liquid paraffin(x -accumulate mesenteric -excessive dose: leak
recommended) ¶-aortic LN out the GIT from anus
paraffinoma
-Docusate sodium/ -emulsifying fat with H2O, -slow acting drugs
potassium/calcium make stool softer
-stimulating effect on small
intestine
5. PROKINETIC -Metoclopramide -facilitate action of ACH
AGENTS -Domperidone peripherally enhance GI
-Tegaserod motility
-act on 5HT3(serotonin)
receptors
Copyright: Aliaa Mohd Radzi aleeya_nlr@yahoo.com