Application of hydrophilic polymers for the preparation of tadalafil solid dispersions: micromeritics properties, release and erectile dysfunction studies in male rats

The objective of the present study was to improve the dissolution rate and aphrodisiac activity of tadalafil by using hydrophilic polymers. Solid dispersions were prepared by solvent evaporation-Rota evaporator using Koliphore 188, Kollidon^® VA64, and Kollidon^® 30 polymers in a 1:1 ratio. Prepared tadalafil-solid dispersions (SDs) evaluated for yield, drug content, micromeritics properties, physicochemical characterizations, and aphrodisiac activity assessment. The optimized SDs TK188 showed size (2.175 ± 0.24 µm), percentage of content (98.89 ± 1.23%), yield (87.27 ± 3.13%), bulk density (0.496 ± 0.005 g/cm3), true density (0.646 ± 0.003 g/cm3), Carr's index (23.25 ± 0.81), Hausner ratio (1.303 ± 0.003) and angle of repose (<25°). FTIR spectrums revealed tadalafil doesn't chemically interact with used polymers. XRD and DSC analysis represents TK188 SDs were in the amorphous state. Drug release was 97.17 ± 2.43% for TK188, whereas it was 32.76 ± 2.65% for pure drug at the end of 2 h with 2.96-fold increase in dissolution and followed release kinetics of Korsmeyer Peppa's model. MDT and DE were noted to be 17.48 minutes and 84.53%, respectively. Furthermore, TK188 SDs showed relative improvement in the sexual behavior of the male rats. Thus the developed SDs TK188 could be potential tadalafil carriers for the treatment of erectile dysfunction.

Isolation and Physical Property Optimization of an Amorphous Drug Substance Utilizing a High Surface Area Magnesium Aluminometasilicate (Neusilin(®) US2)

Control and optimization of the physical properties of a drug substance (DS) are critical to the development of robust drug product manufacturing processes and performance. A lack of isolatable, for example, crystalline, DS solid forms can present challenges to achieving this control. In this study, an isolation scheme for an amorphous DS was developed and integrated into the synthetic route producing DS with optimized properties. An inert absorbent excipient (Neusilin® US2) was used to isolate the DS via a novel antisolvent scheme as the final step of the route. Isolation was executed at kilogram scale utilizing conventional equipment. The resulting 50 wt% DS:Neusilin complex had improved physical stability and exceptional micromeritic and tableting properties. Improved dissolution was observed and attributed to enhanced dispersion and increased surface area. Characterization data suggest a high degree of penetration of the DS into the Neusilin, with DS occupying 70% of mesopore and 12% of macropore volume. This approach has application in the isolation and particle engineering of difficult to isolate DS without additional unit operation, such as spray drying, and has the potential for a high degree of optimization and control of physical properties over the course of DS development.