Antiviral drug disposition and natural health products: risk of therapeutic alteration and resistance.

The HIV/AIDS patient population is known to use natural health products (NHPs) in addition to the several antiretroviral drugs that constitute the treatment regimen for this disease. This review focuses on NHPs and their potential for interactions with antiretroviral agents resulting in therapeutic alterations or resistance. There are conflicting published medical literature reports and very few well-documented human clinical studies that unequivocally demonstrate if this concomitant use increases the risk of interaction/adverse reaction with these therapeutic products. This article outlines some findings from the Canadian domestic adverse reaction case reports associated with the use of antiretrovirals and NHPs. These adverse reaction case reports were specifically examined for patients taking NHPs together with their highly active antiretroviral therapy during or around the time when the adverse reaction developed. Together, the case reports and limited human clinical studies suggest that the risk for therapeutic alterations and resistance can exist due to changes in pharmacokinetic parameters with concomitant use of these therapeutic products.