Pharmacology MCQ Answer 71

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The Correct Answer is A



DRUG

MECHANISM OF ACTION

INDICATIONS & THEURAPEUTICS

ADRs

H2 RECEPTOR ANTAGONIST

Ranitidine (Zantac)

Cimetidine

Famotidine (Pepcid)


• Competitively blocks histamine-stimulated gastric acid secretion

• Blunts parietal cell response to ACh & gastrin

• ~ 90% inhibition of gastric acid secretion

t1/2 = 2-3 hours – problem w/ nocturnal attacks

Can give ↑doses of H2 antags to cover ≥ 6 hrs because of high safety and then only one day dose


• Indication - GERD, gastric & duodenal ulcers

Available OTC - label dosage is half prescription dosage

• Can use prophylactically to prevent reoccurrence after acute event


• Low toxicity - reduce dose in renal dysfunction

• Cimetidine (Tagament) - antiandrogenic - binds microsomal P450


Long-Term NSAID tx causes ulcers at normal doses – co-admin of Famotidine markedly reduces incidence of ulcers

(e.g. ASA for prophylaxis of heart dz)

Category: Pharmacology MCQs

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