Ans. is 'b' i.e., Stimulant purgatives Stimulant purgatives* They are powerful purgatives: often produce griping. They irritate intestinal mucosa and thus were thought to primarily stimulate motor activity.* Though some of them do directly increase motility by acting on myenteric plexuses, the more important mechanism of action is accumulation of water and electrolytes in the lumen by altering absorptive and secretory activity of the mucosal cell.* They inhibit Na+ K+ ATPase at the basolateral membrane of villous cells--transport of Na+ and accompanying water into the interstitium is reduced.* Secretion is enhanced by activation of cAMP in crypt cells as well as by increased PG synthesis.* The laxative action of bisacodyl and cascara is shown to be partly dependent upon increased NO synthesis/action in the colon.* Larger doses of stimulant purgatives can cause excess purgation resulting in fluid and electrolyte imbalance. Hypokalaemia can occur on regular intake.* Routine and long-term use must be discouraged, because it can produce colonic atony.* They can reflexly stimulate gravid uterus, therefore are contraindicated during pregnancy.* Subacute or chronic intestinal obstruction is another contraindication.Choice of drugs for common problems during pregnancy Drug class (condition)Safety uncertain/unsafeSafer alternative1.Antiemetics (morning sickness, other types of vomiting)Domperidone (X) ondansetronPromethazine, Doxylamine Dicyciomine, Prochloperazine Meloclopramide2.Drugs for peptic ulcer and GERDCimetidine, lansoprazoleCisapride (X), mosaprideRanitidine, farmotidine omeprazoie pantoprazole3.Laxatives (constipation)Senna, bisacodyl, docusates saline purgativesDietary fibre, Ispaghula lactulose4.Laxatives (constipation)Diphenoxylate atropine lapetamideOral rehydration salts5.Analgesics (headache, bodyache, joint pain, visceral pain)Aspirin, Metamizol, NSAIDsCOX-2 inhibitors, codeine dextropropoxyphene, morphine (X) pethidine, TramadolParacetamol lbuproten (low dose)6.Cold-cough remediesCodeine, dextromethorphan bromhexine, expectorantsXylometazolineOxymetazolineBudesonide}Nasal drops7.AntiallergicsCetirizine, loratadine Fexpfenadine, astemizole (X)Chlorpheniraminepromethazine