Inhibition of major drug metabolizing CYPs by common herbal medicines used by HIV/AIDS patients in Africa-- implications for herb-drug interactions.
The purpose of this study was to evaluate the potential risk of common herbal medicines used by HIV-infected patients in Africa for herb-drug interactions (HDI). High throughput screening assays consisting of recombinant Cytochrome P450 enzymes (CYPs) and fluorescent probes, and parallel artificial membrane permeability assays (PAMPA) were used. The potential of herbal medicines to cause HDI was ranked according to FDA guidelines for reversible inhibition and categorization of time dependent inhibition was based on the normalized ratio. CYPs 1A2 and 3A4 were most inhibited by the herbal extracts. H. hemerocallidea (IC50 = 0.63 µg/mL and 58 µg/mL) and E. purpurea (IC50 = 20 µg/mL and 12 µg/mL) were the potent inhibitors of CYPs 1A2 and 3A4 respectively. L. frutescens and H. hemerocallidea showed clear time dependent inhibition on CYP3A4. Furthermore, the inhibitory effect of both H. hemerocallidea and L. frutescens before and after PAMPA were identical. The results indicate potential HDI of H. hemerocallidea, L. frutescens and E. purpurea with substrates of the affected enzymes if maximum in vivo concentration is achieved.
Charles
C
Awortwe
Patrick J
PJ
Bouic
Collen M
CM
Masimirembwa
Division of Clinical Pharmacology, Department of Medicine, University of Stellenbosch, PO Box 19063, Tygerberg, Cape Town, 7505, South Africa. charzos@yahoo.com.
Bernd
B
Rosenkranz
D000349:Africa; D019380:Anti-HIV Agents / Q000009:adverse effects*; D065607:Cytochrome P-450 Enzyme Inhibitors / Q000009:adverse effects*; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D015658:HIV Infections / Q000175:diagnosis / Q000188:drug therapy*; D041743:Herb-Drug Interactions; D057166:High-Throughput Screening Assays; D006801:Humans; D007527:Isoenzymes; D008517:Phytotherapy; D028321:Plant Preparations / Q000009:adverse effects*; D010946:Plants, Medicinal; D011994:Recombinant Proteins / Q000378:metabolism; D018570:Risk Assessment; D012307:Risk Factors; D013379:Substrate Specificity
D019380:Anti-HIV Agents; D065607:Cytochrome P-450 Enzyme Inhibitors; D007527:Isoenzymes; D028321:Plant Preparations; D011994:Recombinant Proteins; D003577:Cytochrome P-450 Enzyme System