FORMULATION, CHARACTERIZATION AND IN-VITRO RELEASE STUDY OF SILYMARIN NANOSUSPENSION

Objective: The main objective of this research was to carry out formulation and evaluation of polymeric nanosuspension for silymarin drug by using suitable surfactants to improve its bioavailability. Methods: The silymarin nanosuspension was prepared and lyophilized for enhancing the dissolution of poorly soluble drug. The high pressure homogenization technique was adapted to produce the silymarin nanosuspension respectively using polymers such as Poloxamer188, Poloxamer 407 and Soya lecithin with TPGS as stabilizers in various proportions in combinations. Further, the prepared silymarin nanosuspension were characterized for particle size, poly dispersity index (PDI), zeta potential, drug content, solubility study, in vitro release study, compatibility studies (FT-IR, DSC), in vitro permeability studies and stability studies. Results:The silymarin nanosuspension were prepared and lyophilized. The mean particle size ranged from 100.6 ± 0.16 d.nm to 275.0 ± 0.21 d.nm and the drug content ranged from 94.73 % to 99.61 %. Drug content of polymeric nanosuspension was increased by increasing drug to polymer ratio. The FTIR study confirmed the stable nature of silymarin in the drug-loaded polymeric nanosuspension. In DSC thermogram of pure silymarin a short melting endothermic peak was observed at 148.3°C due to melting point of the pure silymarin. At 263°C owing the presence of amorphous form of the drug in nanosuspension or the dissolution of crystalline drug into the molten carriers. From thermogram it was concluded that the drug and the surfactant do not interact with each other. All the silymarin nanosuspension showed good dissolution property ranging from 90.49 % to 97.96 % in the in-vitro release study after 12 hours. The in-vitro permeability study were shows enhanced diffusion due to huge specific surface area of the nanosuspension droplets and improved permeation of the drug because of the presence of surfactant, which reduces the interfacial tension of formulation. Stability studies were carried out for the best formulation, SF2 indicates that there is no change in drug content and dissolution profile of the formulation. Conclusion: The results obtained in this research work clearly indicated that nanosuspension seems to be a promising drug delivery system, which can provide an effective and practical solution to the problem of formulating drugs with low aqueous solubility and poor systemic bioavailability. Key words: Nanosuspension, high pressure homogenization, Poloxamer 188, poloxamer 407, soya lecithin, TPGS