ABSTRACT:
The present work was aimed at improving dissolution rate of poorly soluble drug nifedipine by developing and characterizing self- micro emulsifying delivery systems (SMEDDS). The solid SMEDDS were then prepared for filling into hard gelatin capsules. Solubility of nifedipine was carried out in various oils, surfactants and co surfactants/ co solvents. Twelve self emulsifying formulations were prepared using various proportions of oil, surfactants and co surfactants/ co solvents in which solubility of nifedipine was high. The stability studies after introduction of nifedipine into different combinations provided the nifedipine liquid SMEDDS which were then evaluated for droplet size and percentage transmittance. The optimized liquid SMEDDS comprised of captex 100, labrasol, tween 60 and propylene glycol. Liquid SMEDDS was then converted into free flowing powder by adsorbing onto Magnesium Aluminium Silicate. Solid SMEDDS were then characterized by scanning electron microscopy (SEM) and differential scanning calorimetric (DSC) measurements. The optimized SMEDDS gave droplet size as low as 20 nm. The SMEDDS formulation showed complete release in 20 minutes as compared with nifedipine which showed a limited dissolution rate. The permeability studies as non everted sac method (more than 50% drug permeated in 30 minutes) also proved efficacy of SMEDDS. The absence of melting peak of nifedipine in DSC studies showed the inhibition of crystallization of drug. Similarities between dissolution and permeation profiles’ of liquid and solid SMEDDS was confirmed by f1/f2 test .Thus, the study confirmed that SMEDDS formulation can be used as a possible alternative to traditional oral formulations of nifedipine to improve its dissolution rate and concomitantly the bioavailability.