H2 receptor blockers

PPIs versus H2 antagonist

Treatment of bleeding peptic ulcers : A meta-analysis of 21 randomized controlled trials evaluating proton pump inhibitors for bleeding ulcers (with or without endoscopic therapy) found a significant and consistent reduction in the risk of rebleeding. In contrast, studies on H2 antagonists have generally produced disappointing results. A meta-analysis concluded that there was a possible minor benefit with intravenous H2 antagonists in bleeding gastric ulcers but no benefit with duodenal ulcers. The relative efficacy of the proton pump inhibitors may be due to their superior ability to maintain a gastric pH at a level above 6.0, and thus protect an ulcer clot from fibrinolysis.

cimetidine (Tagamet ®)

Active ulcer: Oral: 800 mg orally at bedtime or 300mg orally four times daily or 400 mg orally twice daily. IM/IV: 300mg every 6 hours or 37.5 mg/hr continuous infusion.

Active bleed: 37.5 mg/hr continuous IV (maximum 2400mg/day).
Maintanance (duodenal ulcer prophylaxis): 400mg orally at bedtime.

Gastric hypersecretory conditions: 300 to 600mg every 6 hours.

Renal Dosing: >40 ml/min: no change || 20-40 ml/min: give usual dose q8h or give 75% of usual dose. || 0-20 ml/min: Usual dose q12h or give 50% of usual dose.

famotidine (Pepcid ® )

Usual dose (Acute): 40mg orally at bedtime or 20mg orally twice daily.
Maintenance: 20 mg orally at bedtime.
Hypersecretory conditions: 20mg orally every 6 hours. May increase up to 160mg orally every 6 hours.

Famotidine is becoming the preferred agent in many intensive care units. Unlike cimetidine, it has no significant hemodynamic effects nor does it alter hepatic drug metabolism and in preference to ranitidine, it has no adverse effects on platelet production. This favorable safety profile combined with its profound inhibitory effect on gastric acid secretion and its q12h-dosing schedule has made this H2 antagonist exceedingly popular for use as an agent for stress ulcer prophylaxis.

nizatidine (Axid ® )

Usual: 300mg orally at bedtime or 150 mg orally twice daily. Maintenance: 150mg orally at bedtime. Supplied: [150, 300mg capsule]

ranitidine (Zantac ® )

Usual dose: 150mg orally twice daily or 300mg orally at bedtime. Maintenance: 150mg orally at bedtime. Gastric hypersecretory conditions: 150mg orally 2 to 4 times daily. IVPB: 50mg every 6 to 8 hours (Maximum: 400mg/day) Continuous infusion: (preferred in actively bleeding patients): 6.25 mg/hr titrated to gastric pH >4 for prophylaxis or >7.0 for treatment.

Disclaimer

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David F. McAuley, Pharm.D., R.Ph. GlobalRPh Inc.

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