International Journal of Bioassays ISSN: 2278-778X www.ijbio.com R Re es se ea ar rc ch h A Ar rt ti i c cl l e e *Corresponding Author: Mr. Gaurav Upadhyay (M.Pharm), Assistant Professor, Siddhartha Institue of Pharmacy, Shastradhara Road, I.T. Park, Dehradun (UK), India. 1734 EFFECT OF RHODODENDRON FLOWER JUICE ON THE BIOAVAILABILITY OF AMLODIPINE IN RATS Jyoti Upadhyay 1 , Gaurav Upadhyay 2 *, Rohit Joshi 3 and Vijay Juyal 4 1 Himalayan Institute of Pharmacy and Research, Rajawala, Dehradun (UK), India 2 Siddhartha Institute of Pharmacy, Shastradhara Road, I.T. Park, Dehradun (UK), India 3 International Center for Genetic Engineering and Biotechnology, New Delhi, 110067, India 4 Department of Pharmacy, Bhimtal campus, Kumaon University, Nainital (UK), India Received for publication: December 23, 2013; Accepted: January 11, 2014 INTRODUCTION The desirable and undesirable effects of a drug arising from its concentrations at the sites of action are usually related either to the amount administered (dose) or to the resulting blood concentrations, which are affected by its absorption, distribution, metabolism, and/or excretion 1 . Elimination of a drug or its metabolites occurs either by metabolism, usually by the liver or gut mucosa, or by excretion, usually by the kidneys and liver. Drugs and other exogenous lipophilic compounds usually have to be metabolized before they can be excreted from the body. This metabolism occurs by phase I and phase II reactions. In phase I, the majority of drugs undergo biotransformation reactions that are generally mediated by CYP enzymes, oxidative reactions being the most common. In phase II reactions, drug molecules or their metabolites are usually conjugated 2 . Metabolic drug interactions between drugs represent a major concern for the pharmaceutical industry, for regulatory agencies and clinically for health care professionals and their patients. Many drug interactions are a result of induction or inhibition of CYP enzymes 3 . Drug and Juice Interaction Several forms of juice are intended to be safe for human consumption, but at the same time, few juices can produce an interaction with the drugs by altering their pharmacokinetics and subsequent clinical response. Serendipitous findings about 10 years ago in clinical drug study, when grapefruit juice used to mask the taste of ethanol, led to the discovery of a grape- fruit juice felodipine interaction. Felodipine is a dihydropyridine calcium channel antagonist used for the treatment of hypertension; simultaneous administration of felodipine with a single glass of grapefruit juice increased significantly the plasma concentration of felodipine and also increased its hypotensive effect 3 . Since then, grape fruit juice has been shown to increase the plasma concentration of several drugs e.g. cyclosporine, midazolam, and terfenadine. The inhibitory effect of juice is believed to depend on the components which are present in the fruit species 4 . Pharmacokinetic interactions are most frequent mechanism of interactions among medicines and interactions in the metabolic processes are particularly important 5 . Inhibition of drug metabolism by specific drugs, chemicals, fruit species or herbal medications causes increased levels of parent drug, prolonged drug activity and an increased potential for drug toxicity. However there is a little information based on scientific evidence concerning the interaction between other fruit juices and drug metabolized by CYP3A4. This led to conduct further studies on drug and juice interaction 6 . Rhododendron flower juice contains ursolic acid, resins, certain species of flavonoid glycosides like quercetrin, and anthocyanins, having the activity to Abstract: The aim of the study was to determine the effect of rhododendron flower juice on the bioavailability of Amlodipine in rats. This study was carried out in rats as a parallel design study. After the analysis of blood samples, it has been concluded that a component (s) of rhododendron flower juice inhibits the CYP3A4 mediated metabolism of Amlodipine. AUC was determined with the help of Trapezoidal rule. C max and T max were determined from the area under the plasma concentration-time curve. Statistical analysis was performed on the data obtained from both the group of rats. One way Analysis of Variance (ANOVA) from which Tukey-Kramer Multiple Comparisons Test was applied to the data obtained. This test compared all the parameters such as AUC, C max and T max without flower juice and after giving flower juice and the standard deviation of AUC of amlodipine with and without juice was found to be 14.25 and 10.44 respectively. AUC of the amlodipine after giving rhododendron flower juice to rats was significantly increased in comparison to the control group. The Overall result indicates that the oral bioavailability of amlodipine after giving rhododendron flower juice was increased as compared to the amlodipine with water. Keywords: Rhododendron, Bioavailability, Metabolism