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14 Cards in this Set
- Front
- Back
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H2 receptor antagonists (names, etc)
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4 drugs in US - cimetidine, ranitidine, famotidine, nizatidine
Inhibit gastric acid secretion induced by histamine, gastrin, but only partially inhibit acetylcholine-mediated gastric acid release |
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Cimetidine
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Given orally, widely distributed throughout body(including breast milk and placenta), excreted mainly in urine, short serum half-life, 30% is inactivated by liver's microsomal mixed-function oxygenase system, other 70% excreted in urine unchanged, dosage decreased with hepatic or renal failure, side effects of this and other H2-blocker drugs are headache, dizziness, diarrhea, muscular pain. Cimetidine can have endocrine effects, because acts as a nonsteroidal antiandrogen - galactorrhea (constant secretion of milk), reduced sperm count, gymnecomastia, inhibiting cyt P450 oxidase can also increase serum concentrations of other drugs
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Ranitidine
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Longer acting than Cimetidine, 5-10 fold more potent, minimal side effects, doesn't interfere with other drugs through MFO system
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Famotidine
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Similar to ranitidine, but 20-50 times more potent than cimetidine and 3-20 times more potent than ranitidine
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Nizatidine
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Similar to ranitidine in pharm action and potency, but metabolized by the kidney instead of the liver - little first-pass metabolism
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Inhibitors of H+/K+ ATPase proton pump
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5 drugs - omeprazole, iansoprazole, rabeprazole, pantoprazole, esomeprazole. Made in proform, converted to active form which reacts with cyteine residue of proton pump forming stable covalent bond. Takes 18 hours to synthesize new protein. Inhibit acid secretion by ~90%, all drugs are delayed-release and are effective orally, metabolites excreted in urine and feces, generally well tolerated - omeprazole interferes with some drugs, including warfarin, phenytoin, diazepam, cyclosporine
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Prostaglandins
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E2 produced by gastric mucosa, misoprostal is a stable analog of prostaglandin E1, approved for prevention of gastric ulcers induced by NSAIDs, clinically effective only at higher doses that diminish gastric acid secretion, misoprostal produces uterine contractions and can cause dose-related nausea and diarrhea
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Treatment of H. Pylori (Peptic Ulcer Disease)
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2 or more antibiotics + proton pump inhibitor. Antimicrobial agents include amoxicillin, bismuth compounds, clarithromycin, metronidazole, tetracycline
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Antidiarrheals
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Include antimotility agents, adsorbents, and drugs that modify fluid and electrolyte transport
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Antidiarrheals - antimotility agents
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diphenoxylate, loperamide. Active presynaptic opioid receptors in the enteric nervous system to inhibit acetylcholine release and inhibit peristalsis. Side effects - drowsiness, abdominal cramps, dizziness.
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Antidiar. - adsorbents
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Much less effective than antimotility drugs, in addition to causing constipation can interfere with absorption of other drugs. Agents include KAOLIN, PECTIN, METHYLCELLULOSE, ACTIVATED ATTAPULGITE, MAGNESIUM ALUMINUM SILICATE, which presumably work by adsorbing intestinal toxins, microorganisms, and/or coating and protecting intestinal mucosa
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Antidiarrheal - agents that modify fluid and electrolyte transport
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NSAIDS - ASPIRIN, INDOMETHACIN. Probably due to inhibiting of prostaglandin synthesis. BISMUTH SUBSALICYLATE - used for traveler's diarrhea, decreases fluid secretion in the bowel.
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Laxatives
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Can be classified as irritants and stimulants, bulking agents, or stool softeners. Case list - BISACODYL, LACTULOSE, MAGNESIUM HYDROXIDE, (? phenolphthalein?)
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Laxatives - irritants and stimulants
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CASTOR OIL - broken down in small intestine to ricinoleic acid, irritating to gut and causes increased peristalsis.
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