What are proton pump inhibitors? How do they interact with other drugs?

St. John’s Wort

Effect: Possible Harmful Interactions

The herb St.
John’s wort is known to interact with numerous drugs. There
are two potential harmful interactions between St. John’s wort and proton pump
inhibitors.

One study found that the use of St. John’s wort greatly decreases levels of
omeprazole (such as Prilosec) in the body. This would be expected to lead to
markedly reduced efficacy.

The other potential risk is more theoretical. When taken to excess, the herb St.
John’s wort can cause an increased risk of sunburn. Some evidence hints that
proton pump inhibitors might increase this risk.

Vitamin B12

Effect: Supplementation Likely Helpful

Vitamin
B12
deficiency is a concern with the use of all
drugs that reduce stomach acidity. In food, vitamin B12 is always
accompanied by proteins, and it must be separated from them before it can begin to
be absorbed. Following separation, B12 is then attached to a substance
called intrinsic factor, which allows B12 to be absorbed in the
intestines.

Stomach acid plays a role in this separation. If one does not have enough stomach acid, the process of freeing vitamin B12 from protein so that it can be bound to intrinsic factor may be impaired.

Studies suggest that treatment with proton pump inhibitors might significantly reduce the absorption of vitamin B12. There is some evidence that cranberry juice might increase B12 absorption in persons taking proton pump inhibitors, possibly because the juice is somewhat acidic.

Folate

Effect: Supplementation Possibly Helpful

Research on related medications suggests that proton pump inhibitors may slightly
reduce the body’s absorption of folate. The decrease in folate absorption should
be quite small, but because folate deficiency is quite common and potentially
harmful, taking extra folate might make sense as
insurance.

Minerals

Effect: Supplementation Possibly Helpful

By reducing stomach acid levels, proton pump inhibitors might interfere with the
absorption of iron, zinc, and perhaps other minerals. Taking mineral supplements
to meet the U.S. Dietary Reference Intake (formerly known as the Recommended
Dietary Allowance) levels for these nutrients should help.

Bibliography

Aymard, J. P., et al. “Haematological Adverse Effects of Histamine H2-Receptor Antagonists.” Medical Toxicology and Adverse Drug Experience 3 (1988): 430-448.

Mirossay, A., et al. “Potentiation of Hypericin and Hypocrellin-Induced Phototoxicity by Omeprazole.” Phytomedicine 6 (1999): 311-317.

Wang, L. S., et al. “St. John’s Wort Induces Both Cytochrome P450 3a4-Catalyzed Sulfoxidation and 2c19-Dependent Hydroxylation of Omeprazole.” Clinical Pharmacology and Therapeutics 75 (2004): 191-197.