Purpose: To formulate simvastatin orodispersible tablets with high dissolution rate and enhanced bioavailability.

Methods: Simvastatin solid dispersions in β- cyclodextrin, hydroxylpropyl-β-cyclodextrin, and hydroxylbutyl-β-cyclodextrin were prepared in different drug: polymer ratios by kneading and solvent evaporation methods. Compatibility was investigated by Differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) Based on the results of solubility studies, the most suitable solid dispersion was selected and formulated into orodispersible tablets using Emcosoy and K-polacrillin as superdisintegrants, and mannitol and Pullulan as diluents. The tablets were evaluated for wetting and disintegration times, water absorption, and in vtro dissolution.

Results: Increase in drug solubility was dependent on polymer type, concentration and preparation method. Simvastatin-hydroxylbutyl-β-cyclodextrin solid dispersion mixture prepared in 1:2 drug: polymer ratio by solvent evaporation method had a higher solubility than other dispersions. DSC and FTIR indicated the formation of solid dispersion without chemical interaction  between simvastatin and polymer. Orodispersible tablet prepared with Emcosoy and Pullulan showed least wetting and disintegration times (20 and 35 s, respectively), fastest water sorption rate, and the highest dissolution rate (100 % after 20 min).

Conclusion: Orodispersible tablets prepared with Emcosoy as superdisintegratnt and Pullulan as diluents and containig simvastatin solid dispersion in hydroxylbutyl-β-cyclodextrin provides optimum water solubility and hence, drug bioavailability.