Possible Drug–Metabolism Interactions of Medicinal Herbs with Antiretroviral Agents

Abstract

Herbal medicines are widely used by HIV patients. Several herbal medicines have been shown to interact with antiretroviral drugs, which might lead to drug failure. We have aimed to provide an overview of the modulating effects of Western and African herbal medicines on antiretroviral drug-metabolizing and transporting enzymes, focusing on potential herb-antiretroviral drug interactions. Echinacea, garlic, ginkgo, milk thistle, and St. John's wort have the potential to cause significant interactions. In vitro and in vivo animal studies also indicated other herbs with a potential for interactions; however, most evidence is based on in vitro studies. Further pharmacokinetic studies to unveil potential Western and especially African herb-antiretroviral drug interactions are urgently required, and the clinical significance of these interactions should be assessed.

Effects of Short-Term and Long-Term Pretreatment of Schisandra Lignans on Regulating Hepatic and Intestinal CYP3A in Rats

“…CYP3A, the most abundant drug-metabolizing enzyme in human liver and the intestinal wall, is responsible for metabolizing a majority of drugs. Case reports, clinical trials, and in vitro studies have shown a number of important pharmacokinetic interaction risks of herbal medicines with prescribed agents medicated by CYP3A (Hu et al, 2005;van den Bout-van den Beukel et al, 2006). Several methods have been published describing the interactions between herbal medicines and synthetic drugs based on in vitro data.…”

“…Because of the widespread and indiscriminate use of herbal medicines, the potential metabolic herb-drug interactions that may lead to severe adverse reactions have attracted a great attention from both pharmaceutical industries and regulating authorities. In the current literature, there are many references on the metabolic herb-drug interactions, such as typical studies on St. John's wort (Hypericum perforatum) (Rengelshausen et al, 2005;Xie and Kim, 2005), grapefruit juice (Arayne et al, 2005;Paine et al, 2005), and garlic (Allium sativum) (Hu et al, 2005;van den Bout-van den Beukel et al, 2006).…”

Role of the Pharmacist in Caring for Patients with HIV/AIDS: Clinical Practice Guidelines

“…Some herbal products, such as St John's wort, echinacea, garlic, and Gingko biloba, have been shown to induce or inhibit important metabolic pathways involved in the metabolism of protease inhibitors and NNRTIs, including CYP450, uridine 5'-diphospho-glucuronosyltransferase (UGT), and P-glycoprotein pathways. 41 In one case, an HIV-positive man experienced a 68% reduction in efavirenz concentrations, which caused viral breakthrough and drug resistance, following initiation of Gingko biloba, a known inducer of isozyme CYP3A. 42 In another case, elevated plasma concentrations of lopinavir and severe diarrhea were noted with concomitant use of efamol (a component of evening primose oil that has been shown to inhibit isozymes CYP3A4 and CYP2D6 in vitro).…”

Evaluation of Cytotoxic, Genotoxic and CYP450 Enzymatic Competition Effects of Tanzanian Plant Extracts Traditionally Used for Treatment of Fungal Infections

“…In a recent review, potential interactions between commonly used herbal extracts and antiretroviral agents have been described [31]. These interactions can be based on inhibition or induction of CYPs involved in ARV metabolism.…”