Effects of Gingko biloba extract on tissue distribution of fluoxetine and venlafaxine in rats

OBJECTIVE: There are many concerns about the interactions of herbal products with conventional drugs, which are mostly used as multiple drug treatment approach. The present study was designed to evaluate the effect of long-term use of Ginkgo biloba extract (GK) on the absorption and tissue distribution of fluoxetine and venlafaxine. MATERIALS AND METHODS: 46 Wistar rats are utilized and allocated into 8 groups; 2 groups administered the vehicle and saved as control; 4 groups are treated with 100 and 200 mg/kg of GK extract for 30 days; 2 groups are treated with 40 mg/kg verapamil for 10 days. The liver, kidney, and brain distribution of fluoxetine and venlafaxine were evaluated after single oral doses using high performance liquid chromatographic method. RESULTS: 200 mg/kg GK increases fluoxetine concentrations in all studied organs, while GK 100 mg/kg increases venlafaxine levels in kidney tissue and not affected in the other two organs. CONCLUSION: Thirty days treatment with GK (100 mg/kg) increases kidney availability of venlafaxine, while 200 mg GK dose increases fluoxetine availability in the liver, kidney, and brain tissues after single oral doses.