Drug Interactions between aspirin / omeprazole and peppermint oil

ADJUST DOSING INTERVAL: Administration of enteric-coated, gastro-resistant formulations of peppermint oil (e.g., delayed or sustained release capsules) concurrently with antacids may cause premature dissolution of the enteric coating and early release of the peppermint oil, which could lead to gastrointestinal irritation and reduced therapeutic effects. The use of other medications that can reduce gastric acid, such as H2-receptor antagonists and proton pump inhibitors, may also cause similar issues.

MANAGEMENT: Acid-lowering medications should not be administered at the same time as enteric-coated, gastro-resistant formulations of peppermint oil. In general, H2-receptor antagonists and proton pump inhibitors should preferably be avoided, while antacids should be administered at least 2 hours before or 2 hours after the peppermint oil preparation. The labeling for the specific product should be consulted for administration recommendations and other guidance.

Coadministration with proton pump inhibitors may decrease the oral bioavailability of aspirin and other salicylates. The interaction has been studied with omeprazole and aspirin, although data are conflicting. In one study, pretreatment with omeprazole (20 mg/day for 2 days) in 11 healthy volunteers led to a significant and progressively greater reduction in the mean serum salicylate level at 30, 60, and 90 minutes after administration of aspirin (650 mg single dose). The investigators suggest that acid suppression may reduce the lipophilic nature of aspirin, thereby adversely affecting its absorption from the gastrointestinal tract. Another study found no effect of omeprazole pretreatment (20 mg/day for 4 days) on plasma salicylate and aspirin levels, skin bleeding times, or antiplatelet effect of low-dose aspirin (125 mg single dose) in 14 healthy volunteers. However, these results do not exclude the possibility that omeprazole might interfere with the analgesic, antipyretic, or anti-inflammatory effects of aspirin, which has been demonstrated in rats.

Proton pump inhibitors may enhance the release rate of salicylates from enteric-coated formulations due to premature disruption of the coating and intragastric release of the drug secondary to an increase in gastric pH. In eight healthy volunteers, omeprazole pretreatment (20 mg/day for 4 days) did not affect the bioavailability of salicylate from uncoated aspirin tablets but significantly increased the absorption rate of salicylate from enteric-coated sodium salicylate tablets. The clinical significance of this interaction is unknown. Theoretically, it may increase the risk of gastric adverse effects associated with salicylates.