Proton Pump Inhibitors (PPIs) 6 drugs Shut down the stomach's acid pumps almost completely — the strongest acid reducers.
Treats: GERD · Peptic ulcer disease · H. pylori (part of triple therapy) · GI bleed
Long-term use: fractures, low magnesium, B12 deficiency, C. difficile risk, kidney injury — use lowest dose, shortest time. omeprazole, pantoprazole, esomeprazole, lansoprazole, rabeprazole…
H2 Receptor Blockers 3 drugs Turn stomach acid production down (not off) by blocking histamine's signal to acid cells.
Treats: GERD · Mild ulcers · Heartburn on demand
Famotidine needs renal dosing; confusion in older adults and the critically ill. famotidine, cimetidine, nizatidine
Antacids & Mucosal Protectants 5 drugs Neutralize acid on contact, or coat and shield the stomach lining.
Treats: Heartburn relief · Ulcer protection (sucralfate) · NSAID ulcer prevention (misoprostol)
Misoprostol is boxed-warning contraindicated in pregnancy (causes abortion); antacids bind many drugs — separate dosing; magnesium antacids accumulate in renal failure. calcium carbonate, aluminum-magnesium hydroxide, sucralfate, misoprostol, bismuth subsalicylate
Antiemetics 8 drugs Block the brain's vomiting triggers — serotonin, dopamine, histamine, or NK1, depending on the drug.
Treats: Chemo/post-op nausea · Gastroenteritis · Migraine nausea · Motion sickness
Ondansetron prolongs QT; promethazine boxed warnings — tissue necrosis IV, fatal respiratory depression under age 2; metoclopramide boxed warning — tardive dyskinesia. ondansetron, metoclopramide, promethazine, prochlorperazine, scopolamine…
Laxatives 11 drugs Get the bowels moving — by adding bulk, pulling in water, softening stool, or stimulating the gut wall.
Treats: Constipation · Opioid-induced constipation · Bowel prep · Hepatic encephalopathy (lactulose)
Magnesium products accumulate in renal failure; stimulant dependence with chronic use; never give laxatives in suspected bowel obstruction. polyethylene glycol, psyllium, docusate, senna, bisacodyl…
Antidiarrheals 3 drugs Slow the gut down so the body can reclaim water.
Treats: Acute non-infectious diarrhea · IBS-D · Chronic diarrhea
Never slow the gut in bloody/febrile infectious diarrhea or suspected C. difficile — risk of toxic megacolon; loperamide cardiac toxicity at high (abuse) doses. loperamide, diphenoxylate-atropine, bismuth subsalicylate
IBD Agents (5-ASA & Gut Biologics) 7 drugs Calm chronic gut inflammation in ulcerative colitis and Crohn's — from topical-acting mesalamine to immune-targeting biologics.
Treats: Ulcerative colitis · Crohn disease
Biologics: serious infection and TB reactivation — screen before starting; sulfasalazine in sulfa allergy. mesalamine, sulfasalazine, budesonide (gut-targeted), infliximab, adalimumab…
Prokinetics & Misc GI Agents 5 drugs Speed a slow stomach, replace missing enzymes, or manage liver-disease complications.
Treats: Gastroparesis · Pancreatic insufficiency · Hepatic encephalopathy · IBS
Metoclopramide >12 weeks risks permanent tardive dyskinesia; rifaximin is safe but expensive. metoclopramide, pancrelipase, rifaximin, dicyclomine, ursodiol
