Formulation and evaluation of Atorvastatin calcium sustained release matrix tablets

Abstract

In the present research, an attempt has been made to formulate sustained release matrix tablets of Atorvastatin Calcium, a novel statin reported to reduce the morbidity and mortality of cardiovascular diseases, which shows poor bioavailability (12%) and low aqueous solubility (BCS Class II). The matrix tablets were prepared by direct compression method using natural polymers (Xanthum gum -F1, F2, Guar gum -F3, F4, Carragenan -F5, F6) and synthetic polymers (HPMC-K100M -F7, F8 and HPMC- 50 cps -F9, F10) at various concentrations and its effect were compared. The tablets were subjected for weight variation, hardness, thickness, friability, drug content uniformity, in vitro dissolution and FT-IR studies. All the formulations showed compliance with pharmacopoeia standards and the FT-IR spectrum shows compatibility of the drug with excipients. The cumulative drug release for F2, F4 and F6 was 72%, 98% and85% up to 17 h indicating the retarded release due to higher concentration (60 mg) of natural polymers than the other batches and its t_50% values were found to be 12 ½ h and 8 h. The drug release mechanism was found to be Korsmeyers and Peppas model (R²=0.9022) for F2 and zero order (R²=0.9244) for F4 and (R²=0.9348) for F6. The formulations F2, F4 and F6 which was prepared by natural polymers were optimized for the formulation of sustained release matrix tablets of Atorvastatin Calcium.