title: Impact of traditional medicinal plant extracts on antiretroviral drug absorption.
abstract: BACKGROUND
  [corrected] Traditional herbal medicines are often used for the treatment of different diseases in developing countries, especially in the rural areas where a lack of an efficient primary health care system is usually experienced. Many patients infected with the human immunodeficiency virus are taking traditional herbal medicines in conjunction with their modern antiretroviral medication and drug-herb interactions can occur in these cases.
  
  
  OBJECTIVE
  To investigate the effect of water extracts of two traditional medicinal plants, Hypoxis hemerocallidea and Sutherlandia frutescens as well as l-canavanine (a constituent of Sutherlandia frutescens) on the transport of nevirapine across human intestinal epithelial cells.
  
  
  METHODS
  Nevirapine transport in the apical to basolateral and basolateral to apical directions across Caco-2 cell monolayers was determined alone (normal control) and in the presence of verapamil (positive control), water extracts of Hypoxis hemerocallidea and Sutherlandia frutescens and an aqueous solution of l-canavanine. The cumulative transport and apparent permeability coefficient (P(app)) values were calculated and compared.
  
  
  RESULTS
  Nevirapine alone was substantially effluxed in the basolateral to apical direction across the intestinal epithelial cell monolayers, which was statistically significantly (p < or = 0.05) decreased by addition of verapamil, Hypoxis hemerocallidea extract and the l-canavinine solution. The effect of Sutherlandia frutescens on nevirapine transport was not statistically significantly different from the control.
  
  
  CONCLUSIONS
  Hypoxis hemerocallidea and l-canavanine interact with the efflux of nevirapine across intestinal epithelial cells and therefore can potentially increase the bioavailability of this antiretroviral drug when taken concomitantly.
authors.affiliation: Department of Pharmacy, University of Limpopo (Medunsa Campus), P.O. Box 218, Ga-Rankuwa 0204, South Africa.
authors.forename: L
authors.initials: L
authors.lastname: Brown
authors.forename: O
authors.initials: O
authors.lastname: Heyneke
authors.forename: D
authors.initials: D
authors.lastname: Brown
authors.forename: J P H
authors.initials: JP
authors.lastname: van Wyk
authors.forename: J H
authors.initials: JH
authors.lastname: Hamman
mesh_terms: D019380:Anti-HIV Agents / Q000493:pharmacokinetics*; D018938:Caco-2 Cells; D002121:Calcium Channel Blockers / Q000008:administration & dosage / Q000493:pharmacokinetics; D002172:Canavanine / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D004338:Drug Combinations; D007887:Fabaceae / Q000737:chemistry*; D006801:Humans; D027802:Hypoxis / Q000737:chemistry*; D007408:Intestinal Absorption / Q000187:drug effects; D016488:Medicine, African Traditional; D019829:Nevirapine / Q000008:administration & dosage / Q000493:pharmacokinetics; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology; D010946:Plants, Medicinal / Q000737:chemistry*; D013019:South Africa; D013535:Suspensions; D014700:Verapamil / Q000008:administration & dosage / Q000493:pharmacokinetics
chemical_list: D019380:Anti-HIV Agents; D002121:Calcium Channel Blockers; D004338:Drug Combinations; D010936:Plant Extracts; D013535:Suspensions; D002172:Canavanine; D019829:Nevirapine; D014700:Verapamil