Ginkgo-efavirenz interaction in patients with HIV

Researchers from the Netherlands report a patient whose HIV viral load increased with the development of drug resistance because ginkgo biloba interacted with efavirenz (Sustiva).

First, the details.

  • The patient confirmed taking his antiretroviral therapy, never missing a dose.
  • His treatment consisted of efavirenz combined with FTC (emtricitabine; Emtriva) and tenofovir (Viread), which started in 2005.
  • In late 2007, he experienced a virological treatment failure, characterized by K103N and M184V HIV resistance mutations.
  • A medical history revealed that the only product this patient was taking was ginkgo biloba.
  • Using stored blood samples taken during the 2 years of efavirenz treatment, the researchers checked concentrations of the drug in the patient’s blood.

And, the results.

  • In 2006, the peak blood level of efavirenz was 1.26 mg/L (within the therapeutic range), and the patient’s viral load was undetectable.
  • In February 2008, the peak blood level of efavirenz was 0.48 mg/L (non-therapeutic), and the patient’s viral load was 1780 copies/mL.

The bottom line?
The authors concluded, “Intake of gingko can decrease human plasma efavirenz levels, may result in virological failure, and should be discouraged.”

Why might this patient have started taking ginkgo in addition to his HIV treatment?

Aidsmap News tells us, “Gingko is… thought to have beneficial effects on concentration, memory, dementia and depression. Of note, efavirenz can cause side-effects such as poor concentration and depression.”

Like efavirenz, ginkgo is metabolized using P450 liver enzymes.

5/21/09 16:55 JR

Hi, I’m JR

John Russo, Jr., PharmD, is president of The MedCom Resource, Inc. Previously, he was senior vice president of medical communications at, a complementary and alternative medicine website.