Hypertension is common disease and many people are taking herbs and other plant-based dietary supplements to improve their health. The aim of this study was to assess the published clinical evidence on herb-drug interaction for the management of hypertension patients.
Design and Method:
We systematically searched papers through the MEDLINE, OASIS, CNKI, J-stage and CiNii until November 2014. Searching queries were made with 493 herbal plants, 72 herb formulas, 148 prescribed Kampo drugs and 81 antihypertensives. We reviewed the relevant studies and extracted information about herb-drug interactions, level of evidence, adverse events of herb-drug interaction studies, the intensity and the causality of the adverse reactions by using WHO-UMC adverse drug reaction causality assessment.
Total 141 papers were analyzed and 100 herb-drug pairs (34 antihypertensives, 49 botanical foods, 32 oriental herb drugs, 2 western herbs) were reported in those articles. 49 herbs increased antihypertensive effects, 13 herbs decreased antihypertensive effects. 23 herbs did not show any interactions, 3 herbs showed conflicting interaction results. 35 herb-drug interactions were reported with pharmacodynamics results, 19 herb-drug interactions were reported with randomized control trial results, 23 herb-drug interactions were reported with results of non-randomized control trial or case report. In 39 herb-drug pairs 28 kinds of adverse reactions were reported. Rhabdomyolysis, dyspnea, paralysis with electrolyte abnormality and dermatitis were reported as serious adverse effects enough to be hospitalized. According to WHO-UMC causality criteria, we could assess the reactions at 29 possible, 5 probable, 3 unlikely, 1 unclassifiable causality.
Although many reports on antihypertensives-herb interactions were published, few studies have been conducted the laboratory analysis of suspect preparations. Present knowledge of herb-drug interactions is incomplete and adverse reaction may put individuals at risk. More research is still needed and health-care practitioners should be careful about using herb and hypertensive drugs.