What are tetracyclines? How do they interact with other drugs?

Minerals

Effect: Take at a Different Time of Day

Numerous minerals, including aluminum (found in many antacids), bismuth (in Pepto-Bismol), calcium, iron, magnesium, and zinc, interfere with the absorption of medications in the tetracycline family (and vice versa). The minerals and the drugs attach to each other and form insoluble chemicals that simply pass out of the digestive tract. The best solution is to avoid taking supplements that contain these minerals within the two hours before or after taking a tetracycline medication.

Dong Quai, St. John’s Wort

Effect: Possible Harmful Interaction

Tetracycline antibiotics have been reported to cause increased sensitivity to the sun, amplifying the risk of sunburn or skin rash. Because St. John’s wort and dong quai may also cause this problem, taking these herbal supplements during tetracycline treatment might add to this risk. People should use sunscreen or wear protective clothing during sun exposure if they are taking one of these herbs with a tetracycline antibiotic.

Citrate

Effect: Possible Harmful Interaction

Potassium citrate, sodium citrate, and potassium-magnesium citrate are sometimes used to prevent kidney stones. These supplements reduce urinary acidity and can therefore lead to decreased blood levels and effectiveness of tetracycline antibiotics.

Bibliography

Campbell, N. R., and B. B. Hasinoff. “Iron Supplements: A Common Cause of Drug Interactions.” British Journal of Clinical Pharmacology 31 (1991): 251-255.

Neuvonen, P. J. “Interactions with the Absorption of Tetracyclines.” Drugs 11 (1976): 45-54.

Ohnishi, M., et al. “Effect of a Kampo Preparation, Byakkokaninjinto, on Pharmacokinetics of Ciprofloxacin and Tetracycline.” Biological and Pharmaceutical Bulletin 32 (2009): 1080-1084.

Thappa, D. M., and J. Dogra. “Nodulocystic Acne: Oral Gugulipid Versus Tetracycline.” Journal of Dermatology 21 (1994): 729-731.