Author(s): P. Vijay Prakash1*, S. Rajashekhar2 and B. Mayuri3
Darifenacin is a muscarinic M3 selective receptor antagonist, which is intended for symptomatic treatment of urge incontinence and/or increased urinary frequency and urgency as may occur in patients with overactive bladder syndrome. Therefore the present investigation concerned with the development of once-a-day darifenacin hydrobromide extended release tablets to extend the duration of action up to 24 hrs by controlling the dissolution rate using different viscosity grades of HPMC. The compatibility between drug and excipients were determined by using DSC. Eight formulations (F1 to F8) of darifenacin hydrobromide extended release tablets were developed by direct compression method using HPMC K4M CR and HPMC K 100M CR, as polymers at different ratios. Formulation F-6 containing 45 % of HPMC K4M CR & 5 % of HPMC K100M CR was found to be the optimized formulation based on in- vitro release of drug i.e. 82 % of drug release was observed in 16 hrs & up to 98 % in 24 hours. Kinetics to the in-vitro release of drug for the formulation, F-6 showed that it followed first order release (R2 = 0.9686) and release mechanism followed was Hixson Crowell cube root law (R2 =0.9816). Further, in-vitro release pattern of F-6 was found to be super imposable (i.e. the similarity factor f2 was found to be 81.90) with the marketed product ENABLEX. F-6 formulation was found to be stable during accelerated stability studies conducted at 40 °C / 75% RH for three months as per ICH guidelines.