Diabetics who are taking rosiglitazone (Avandia), which is one of a new generation of treatments for type 2 diabetes, should not also take St. John’s wort, reveals a new study presented at the annual meeting of the American Society of Pharmacology and Therapeutics in Orlando, Fla.
Study author Matthew Hruska, PharmD, from the University of Florida College of Pharmacy in Gainesville, explains that many patients with diabetes turn to alternative therapies including St. John’s wort, a popular herbal remedy used to treat mild depression and insomnia. In previous studies, St. John’s wort has shown to increase the clearance of a number of drugs.
Hruska and his colleagues set out to investigate the effect of St. John’s wort on how rosiglitazone is metabolized in the body. Twenty-seven participants received eight milligrams of rosiglitazone in the presence and absence of 900 milligrams of daily St. John’s wort. After examining blood and urine samples, researchers found that St. John’s wort hastens the elimination of rosiglitazone from the body, so that less of the drug remains to help control blood sugar.
“Patients with diabetes should talk with their doctors or pharmacists about any herbal products they are taking or plan to take, so that potentially harmful interactions can be identified and avoided,” Hruska concludes.