Famotidine and omeprazole drug interactions

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Famotidine and Omeprazole Drug Interactions: Pharmacokinetics and Safety

Drug Interaction with Other Medications

Omeprazole, a proton pump inhibitor, and famotidine, an H2-receptor antagonist, are both used to reduce stomach acid. However, their interactions with other drugs differ. Omeprazole can significantly increase blood levels of drugs metabolized by CYP enzymes, such as tacrolimus, due to its inhibitory effect on CYP2C19, CYP3A4, and CYP3A5. In contrast, famotidine does not significantly affect tacrolimus levels, making it a safer choice for patients on this immunosuppressant after kidney transplantation . Similarly, omeprazole and other PPIs can increase plasma methotrexate levels by inhibiting the organic anion transporter 3 (OAT3), while famotidine shows little effect on methotrexate elimination, reducing the risk of drug-drug interactions in patients receiving high-dose methotrexate .

Combined Use: Acid Suppression and Clinical Efficacy

Combining famotidine and omeprazole can provide both rapid and sustained acid suppression. Studies show that this combination raises gastric pH more quickly and maintains it longer compared to either drug alone, which may be beneficial for conditions requiring prompt and prolonged acid control . Clinical trials in patients with reflux esophagitis and peptic ulcers also report that the combination is more effective in symptom relief and acid suppression than monotherapy with either drug 91.

Safety and Adverse Effects

Both omeprazole and famotidine are generally safe, but their side effect profiles differ slightly. Omeprazole may cause more frequent mild adverse reactions compared to famotidine, but these effects are usually self-limiting . In animal studies, combining low doses of amlodipine with either famotidine or omeprazole enhanced antiulcer effects, suggesting that lower doses of these acid-suppressing drugs may be effective when used together or with certain other medications .

Cardiovascular and Gastrointestinal Considerations

Famotidine may reduce cardiac output and stroke volume in patients with heart failure, while omeprazole does not show significant cardiovascular effects . In veterinary studies, both omeprazole and famotidine increased the frequency of gastrointestinal adverse events when used as prophylaxis with NSAIDs, suggesting caution in such combinations, at least in dogs .

Comparative Efficacy

Omeprazole is generally more effective than famotidine for healing peptic and gastric ulcers, providing higher healing rates and better symptom relief, especially over longer treatment periods 710. Both drugs are safe for elderly patients, but omeprazole may offer slightly better outcomes in terms of ulcer healing and symptom improvement .

Conclusion

Famotidine and omeprazole have distinct drug interaction profiles, with omeprazole posing a higher risk for interactions with drugs metabolized by CYP enzymes and eliminated by OAT3. Combining the two can enhance acid suppression, but individual patient factors and potential drug interactions should guide therapy choices. Both drugs are effective and generally safe, but omeprazole may offer superior efficacy for ulcer healing, while famotidine may be preferred in patients at risk for certain drug interactions.

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Most relevant research papers on this topic

Antiulcer effect of amlodipine and its interaction with H2 blocker and proton pump inhibitor in pylorus ligated rats

Amlodipine and its combination with famotidine or omeprazole significantly reduce gastric ulcers in rats, suggesting patients treated with amlodipine may be less prone to peptic ulcers and require lower doses of antiulcer agents.

Non-RCTAnimal Study

2006·

31citations

·A. Bhave et al.

Cardiovascular effects of omeprazole and famotidine.

Famotidine significantly reduces stroke volume and cardiac output in patients with congestive heart failure, while omeprazole does not show significant cardiovascular effects.

RCT

1992·

9citations

·A. Halabi et al.

Assessment of omeprazole and famotidine effects on the pharmacokinetics of tacrolimus in patients following kidney transplant–randomized controlled trial

Omeprazole significantly increases blood exposure of tacrolimus, making famotidine a safer option for patients following kidney transplantation.

RCT

2024·

3citations

·Miłosz Miedziaszczyk et al.

A prospective, randomized, placebo-controlled, double-blinded clinical trial comparing the incidence and severity of gastrointestinal adverse events in dogs with cancer treated with piroxicam alone or in combination with omeprazole or famotidine.

Omeprazole did not reduce gastrointestinal adverse events and may have increased them in dogs with cancer treated with single agent piroxicam, suggesting it should not be used as a prophylaxis with NSAIDs.

RCTAnimal Study

2021·

15citations

·Marejka H Shaevitz et al.

Effects of proton pump inhibitors and famotidine on elimination of plasma methotrexate: Evaluation of drug–drug interactions mediated by organic anion transporter 3

Co-administration of proton pump inhibitors (PPIs) with methotrexate increases plasma levels, partially due to inhibition of organic anion transporter 3, while famotidine shows little inhibitory effect.

In Vitro Study

2017·

34citations

·Katsuya Narumi et al.

Can famotidine and omeprazole be combined on a once-daily basis?

Famotidine and omeprazole can be combined on a once-daily basis for rapid acid control and long-lasting antisecretory effect.

Non-RCT

2007·

18citations

·L. Fändriks et al.

Clinical Observe of Omeprazole and Famotidine in Treating 68 Peptic ulcer

Omeprazole is a safer and more effective treatment for peptic ulcers compared to famotidine, with a higher effective rate and lower adverse reactions.

RCT

2005·

0citations

·W. An

Antisecretory activity of omeprazole in the conscious gastric fistula cat: comparison with famotidine.

Omeprazole has a less potent antisecretory effect than famotidine, but its antisecretory profile differs significantly from famotidine, with omeprazole having a longer lasting inhibitory effect.

Non-RCTAnimal Study

1989·

7citations

·G. Coruzzi et al.

Clinical Analysis on the Effect of Omeprazole Combined with Famotidine on the Treatment of Reflux Esophagitis

Omeprazole combined with famotidine effectively restrains stomach acid secretion, providing reliable curative effect on reflux esophagitis.

RCT

2014·

0citations

·Z. Qin

Efficacy of Omeprazole Versus Famotidine in the Short-Term Treatment of Gastric Ulcer

Omeprazole 20 mg once daily and famotidine 20 mg twice daily are both safe for short-term treatment of gastric ulcers in aged patients, with omeprazole providing higher symptomatic relief.

RCT

1994·

0citations

·Chiun‐ku Lin et al.

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