In vitro Binding Chemistry of Amlodipine Besylate (Calcium Channel Blocker) and Atorvastatin Calcium (HMG-CoA Reductase Inhibitor) to Serum Albumin and their Mutual Effect to Displace Each Other from the Binding Site
Combination therapy is now very common for the effective management of cardiovascular problems. The aim of the present study was to evaluate how clinically two important drugs, Amlodipine Besylate and Atorvastatin Calcium, bind with serum protein and the effect of drug-protein binding when they administered concomitantly. In this study the binding chemistry of Amlodipine and Atorvastatin to Bovine Serum Albumin (BSA) was evaluated by Equilibrium dialysis method utilizing Warfarin Sodium (site-I specific probe) and Diazepam (site-II specific probe). Association constant and number of binding sites of the experimental drugs were carried out at pH values of 6.4 and 7.4. The non-liner curve of the plot suggests the presence of at least two classes of binding site (low affinity binding site and high affinity binding site) of experimental drugs to BSA. In both cases of high affinity binding site and low affinity binding, value of association constants of experimental drugs were found higher at pH 7.4. Both of the experimental drugs found to bind site-I preferentially as both of drugs displaced Warfarin Sodium more from the binding site on BSA than that of Diazepam. During concurrent administration of Amlodipine Besylate and Atorvastatin Calcium in presence or absence of diazepam, it was found that the ability of Atorvastatin Calcium to displace Amlodipine Besylate is more than the ability of Amlodipine Besylate to displace Atorvastatin Calcium from the binding site on BSA. The ability of experimental drugs to displace each other is found more in presence of Diazepam. As both drugs compete for the same binding site care should be given during concurrent administration of these two drugs.
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