Onset of action of famotidine
Pro Research Analysisby 
Searched over 200M research papers
Famotidine Onset of Action: Key Pharmacokinetic Insights
Onset of Action in Healthy Individuals and Patients
Famotidine, a histamine H2-receptor antagonist, typically begins to inhibit gastric acid secretion within one hour after oral administration in healthy individuals and those with gastric hypersecretory states. The maximum effect is usually reached within one to three hours after dosing, and the duration of action for standard doses (20–40 mg) lasts about 10 to 12 hours 3469. When compared to other H2-receptor antagonists like cimetidine and ranitidine, famotidine has a similar onset of action but a longer duration of effect 57.
Comparison with Other Acid-Reducing Agents
In direct comparisons, the onset of acid inhibition with over-the-counter doses of famotidine (10 mg) occurs at approximately 35 minutes after administration, which is similar to cimetidine (200 mg) . However, when compared to antacids like calcium carbonate, famotidine has a slower onset. Calcium carbonate acts within the first 30 minutes, while famotidine’s effect typically begins after about 90 minutes post-administration, but its duration is much longer—lasting at least 540 minutes (9 hours) .
Onset in Special Populations: Hemodialysis Patients
In hemodialysis patients, the onset of famotidine’s action is significantly delayed compared to healthy controls. The mean onset in hemodialysis patients is around 90–99 minutes, while in healthy individuals it is about 36–54 minutes, depending on the time of administration. Additionally, the duration of action is prolonged in hemodialysis patients .
Summary of Onset and Duration
- Oral administration in healthy adults: Onset within 1 hour, maximum effect in 1–3 hours, duration 10–12 hours 3469.
- Over-the-counter dose (10 mg): Onset at about 35 minutes, with a rapid and superior effect compared to cimetidine .
- Compared to antacids: Slower onset (about 90 minutes) but much longer duration .
- Hemodialysis patients: Delayed onset (90–99 minutes) and prolonged duration .
Conclusion
Famotidine generally begins to work within one hour after oral administration in most individuals, with a slightly faster onset at lower doses and a delayed onset in patients with renal impairment. Its onset is slower than that of antacids but comparable to other H2-receptor antagonists, and it provides a longer duration of acid suppression.
Sources and full results
Most relevant research papers on this topic