Pharmacokinetic interactions of medicinal herbs and drugs

Abstract

Introduction: The utilization on a large scale from 30 to 85% of basic and active compounds from plants according to WHO data is an actual problem of modem medicine due to the possible interactions with drugs. International bodies (WHO, FDA, EMEA, EFSA) are much concerned about the spreading of medical herbs marketing which do not contain a proper reference material and/or not being certified by the WHO. The problem becomes even more complicated due to the fact that vegetal drugs are used concomitantly with medicines as patients and even doctors do not always pay the necessary attention to this problem considering medical herbs inoffensive and not being harmful for health. Purpose and objectives: is to analyze bibliographic data bases which refer to the significance of pharmacokinetic interactions and the consequences of the associated use of vegetal drugs and medicines. The results and discussion: Analysis of literature showed the existence of hundreds of experimental and clinical studies, of cases referring to interactions of approximately 50-85 of medical herbs and drugs, many of which demonstrate clinical significance. It was proved during this research that the pharmacokinetic interactions take place at different levels of absorption, distribution, metabolism and elimination. A particular interest for medical practice is the concomitant utilization with medicines with drugs from rattle (Hypericum perforatum), grapefruit (iCitrus paradisi), ginseng (Panax ginseng), ginkgo biloba (Ginkgo biloba), garlic (Allium sativum). echinaceea {Echinacea purpurea), thistle (Silybum marianum) etc. The most important pharmacokinetic interactions were reported at the level of the cytochrome P-450 activity and of the conveyors (P-glycoprotein etc.). It was established that the grapefruit, echinaceea, green tea, garlic, milk thistle, licorice, chamomile, lemon Chinese are inhibitors of P-450 cytochrome (CYP 1A2, 2C9, 2C19, 2D6, 2E1, 3A4 etc.), while the Hypericum perforatum, Panax ginseng, eleuterococcus, rosemary, green tea, Echinaceea purpureae manifested as inductors. Some of the plants (echinaceea, green tea, ginseng etc.) had an effect on CYP 3A4 in liver and as inhibitor of isoenzyme respectively in the intestine. Recent studies showed an important influence of medical herbs on the activity of transporting systems, especially on P-glycoprotein, located in the intestine, liver, kidney, hematoencephalic barrier, placenta, testicles. The P-glycoprotein acts as an efflux pump, and its induction or inhibition will influence the absorption, transport and the elimination of drugs. Conclusion: Medicinal herbs when used concomitantly with medicines will show pharmacokinetic interactions with essential changes of the level of medicines in the body and respectively of therapeutic effects. These data require adequate information given by the doctors, pharmacists and patients, with their detailed description in the instructions and medical literature as well.