Formulation design and evaluation of self micro emulsifying drug delivery system [SMEDDS] of valproic acid

ABSTRACT

The present investigation was aimed at developing a stable self micro emulsifying drug delivery system [SMEDDS] of valproic acid [VPA] and evaluating its in vitro potential. The solubility of VPA was determined in various vehicles. Pseudoternary phase diagrams were used to evaluate the micro emulsification existence area and the release rate of VPA was investigated using a dissolution method. SMEDDS were characterized for clarity, precipitation and particle size distribution. Formulation development and screening was done based on results of solubility from phase diagram. The optimized formulation used for in vitro dissolution was composed of castor oil [38.4%], Cremaphor RH 40 [42.4%], PEG 400 [14.4%]. The SMEDDS formulation showed complete release in 15 min. as compared with the plain drug and conventional marketed formulation which showed a limited dissolution rate. VPA loaded SMEDDS were subjected to various conditions of storage as per ICH guidelines for 3 months. VPA SMEDDS successfully withstood the stability testing. It has been found that dissolution profile of valproic acid from SMEDDS was much improved than valproic acid