H2 antagonist
H2 histamine receptor antagonist
- ↓ parietal-cell acid secretion
- Heals ulcers and reflux
- Less complete suppression than PPIs
- Tolerance develops within weeks
- Possible impact on histamine-regulated appetite pathways, reduced ghrelin production (hunger hormone)
- modest potential for weight loss
- Possible benefit in schizophrenia
- Trimipramine (TCA) blocks
Drugs with this mechanism (4)
- Cimetidine — The first H2 blocker; a notable CYP inhibitor with anti-androgen effects.
- Famotidine — The most-used H2 blocker; few drug interactions.
- Nizatidine — H2-blocker for acid reflux.
- Ranitidine — Reformulated H2 blocker returned to the US market after its NDMA-related withdrawal.
Self-check
- How complete is H2-blocker acid suppression compared with PPIs?
Less complete. - When can tolerance to H2 blockade develop?
Within weeks.
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