DESIGN AND EVALUATION OF SOLID DISPERSED TADALAFIL TABLETS

Tadalafil (TD), a PDE-5 inhibitor, belongs to BCS class II. It is poorly soluble in water and requires enhancement in solubility and dissolution rate for increasing its oral bioavailability. In the present investigation, solid dispersed systems of tadalafil with poloxamer₁₈₈ and sodium starch glycolate were prepared using solvent evaporation technique. The dissolution rate of the drug and poloxamer₁₈₈ based solid dispersion was significantly higher than the sodium starch glycolate (SSG) based preparations and pure drug which reaches closer to the dissolution profile of marketed product. This was due to an increase in surface area of drug available for dissolution. Characterization of binary systems with FTIR studies demonstrated the presence of strong hydrogen bonding interactions, a significant decrease in crystallinity and the possibility of existence of amorphous entities of the drug. In the binary systems tested, 1:0.5 proportion of Tadalafil/poloxamer₁₈₈ showed rapid dissolution of tadalafil (DE30 56.68 %). In the binary systems, tested (1:0.5) proportion of tadalafil/poloxamer₁₈₈ showed rapid dissolution of tadalafil. In contrast, higher proportion of polaxmer₁₈₈ (1:1) offered no advantage towards dissolution enhancement of the drug, indicating altered rheological characters of the polymer at its higher concentration, which might have retard the release rate of tadalafil. The tablets were prepared for the optimized formula of solid dispersion, by wet granulation technique. The solid dispersion tablets were evaluated and compared with tadalafil marketed product.