Pharmacodynamic and Pharmacokinetic Interactions of Propranolol with Garlic (Allium sativum) in Rats

Garlic preparations and propranolol (PRO) are agents recognized as cardioprotective and potent antihypertensive agents when they are used individually. However, there is no report available to explain the role of combined therapy during simultaneous hypertension and myocardial damage in rats. We aimed to determine the pharmacokinetic and pharmacodynamic interaction of PRO with garlic homogenate (GH), in rats. The influence of garlic on pharmacokinetics of PRO was determined by HPLC method; while pharmacodynamic interaction was studied in animals with hypertension (10% fructose) and myocardial damage (isoproterenol, 175 mg kg(-1), s.c. 2 days). PRO was given orally at 10 mg kg(-1) for 1 week, whereas, GH was administered at three different doses of 125, 250 and 500 mg kg(-1), p.o. in their respective groups during fourth to sixth week of high fructose (HF) period, once daily. Systolic blood pressure (SBP), heart rate, cholesterol, triglycerides, glucose, creatine phosphokinase-MB, lactate dehydrogenase, superoxide dismutase and catalase were measured and histopathological studies were carried out. The bioavailability and half life of PRO were significantly enhanced by 2- and 3-fold, respectively, in animals pretreated with garlic (250 mg kg(-1)). Administration of PRO and low to moderate doses of GH (125, 250 mg kg(-1)), either alone or together showed fall in fluid intake and body weight. The combined therapy of GH 250 mg kg(-1) and PRO was found to be most effective in reducing SBP, cholesterol, triglycerides and glucose. These observations suggest that careful addition of garlic in moderate doses in PRO regimen might result in beneficial effect during treatment of hypertensive animals with myocardial damage.