Experts believe Ginkgo biloba, a natural product used in vitamin supplements, may be harmful if taken together with HIV medication.
A recent Canadian health department report suggesting that there could be a potential negative drug-herb interaction between the HIV drug Efavirenz (Sustiva) and a herbal product, Ginkgo biloba, has sparked concern among HIV experts in South Africa.
The herb is contained in many products sold locally in the form of vitamins, natural supplements and energy boosters that many HIV-positive patients may take without alerting their doctors, said HIV expert Francois Venter from the Wits Reproductive Health and HIV Institute at the University of the Witwatersrand.
According to the Mayo Clinic, a United States-based medical research and treatment organisation, available evidence supports the herb’s used for “managing dementia, anxiety, schizophrenia and cerebral insufficiency [insufficient blood flow to the brain]”.
University of Cape Town head of clinical pharmacology Gary Maartens says Efavirenz is a widely used antiretroviral (ARV) drug in South Africa in the first line of treatment (a combination of drugs that a person is given when they are first placed on treatment) for HIV.
Beware the ‘natural’
The authors of the report published in the Canadian health department’s July Canadian Adverse Reaction Newsletter said Ginkgo biloba had most likely interacted with Efavirenz in a case involving a man who had been taking his antiretroviral drugs along with the herb.
The 41-year-old HIV-infected man had been on ARVs for 10 years with a low viral load (the level of the virus in his blood) until routine blood tests detected a rise in his viral load.
He admitted to the daily use of other supplements, including Ginkgo biloba. After he stopped using the product, his HIV was re-suppressed.
Venter said patients on ARVs need to be more “sceptical about natural remedies” as some of them have proved to be quite harmful, containing toxins like lead and other heavy metals.
“We don’t know what they contain and multiple reports say these so-called natural remedies are contaminated with all sorts of toxins that might lower the efficacy of ARVs,” he said.
About 90% of people living with HIV in South Africa consult traditional healers for supplementary treatment, according to a 2012 article published in the South African Medical Journal.
“People really need to be careful about what they classify as natural; they may not be as natural as they often think they are,” he said.
Eugenia Barros, a researcher at the Biosciences Unit of the Council for Scientific and Industrial Research in South Africa, suggests natural health products are often “complex mixtures containing organic compounds, many of which can induce and/or inhibit the enzymatic pathways” involved in the metabolism of ARV drugs.
In her article published on the InTechopen website titled “Interaction of traditional medicines against HIV, nutrients and ARVs”, Barros says there are “varied reports on the level of interaction with certain natural health products, resulting in changes in the efficacy of the ARV treatment”.
New regulations for natural or complementary medicines were published last year, requiring stricter vetting processes for safety and efficacy, similar to those used for pharmaceutical drugs.
However, the sector is currently challenging these in court, arguing that these products are used in a different way to pharmacological drugs.
“I think it’s simply sensible to avoid all these unregulated products; they’re untested and impossible in our current environment to assess for safety,” said Venter.
Phyllis Mbanje is Bhekisisa fellow