In vitroandin vivobehavior of ground tadalafil hot-melt extrudates: How the carrier material can effectively assure rapid or controlled drug release
Different types of ground hot-melt extrudates loaded with 10, 20 or 30 % of the poorly water-soluble drug tadalafil were prepared and characterized in vitro and in vivo (in rats). Soluplus was used as an amorphous carrier material, whereas mannitol and lactitol were studied as crystalline matrix formers. The systems were characterized using X-ray powder diffraction, thermogravimetric analysis coupled with quadruple mass spectrometry, differential scanning calorimetry, X-ray computed microtomography, in vitro drug release measurements and monitoring of drug plasma levels upon oral administration to rats. The pure drug substance and physical mixtures of tadalafil with the carrier materials were used as references. Importantly, the bioavailability of this poorly water-soluble drug could be substantially increased with the proposed formulations, and the in vitro and in vivo release rates could be effectively adjusted by choosing the appropriate type of carrier material: Whereas mannitol-based ground hot-melt extrudates rapidly released the drug and led to an early rise in drug plasma concentrations, Soluplus-based systems released tadalafil more slowly, resulting in delayed plasma peaks. These behaviors could be explained by the rapid disintegration/dissolution of the porous mannitol-based formulations, whereas Soluplus significantly swelled and the dissolved drug had to diffuse through the polymeric network prior to release. Blending these formulations can be expected to allow providing elevated drug concentrations in vivo during prolonged periods of time upon one single administration with a rapid onset of drug action.