Polyamidoamine (PAMAM) dendrimers as potential release modulators and oral bioavailability enhancers of vardenafil hydrochloride.

Vardenafil hydrochloride (VAR) is an erectile dysfunction treating drug. VAR has a short elimination half-life (4-5 h) and suffers low oral bioavailability (15%). This work aimed to explore the dual potential of VAR-dendrimer complexes as drug release modulators and oral bioavailability enhancers. VAR-dendrimer complexes were prepared by solvent evaporation technique using four dendrimer generations (G4.5, G5, G5.5 and G6) at three concentrations (190 nM, 380 nM and 950 nM). The systems were evaluated for intermolecular interactions, particle size, zeta potential, drug entrapment efficiency percentages (EE%) and drug released percentages after 2 h (Q2h) and 24 h (Q24h). The results were statistically analyzed, and the system showing the highest desirability was selected for further pharmacokinetic studies in rabbits, in comparison to Levitra® tablets. The highest desirability (0.82) was achieved with D10 system comprising VAR (10 mg) and G6 (190 nM). It possessed small particle size (113.85 nm), low PDI (0.19), positive zeta potential (+21.53), high EE% (75.24%), promising Q2 h (41.45%) and Q24 h (74.05%). Compared to Levitra® tablets, the significantly (p < 0.01) delayed Tmax, prolonged MRT(0-∞) and higher relative bioavailability (3.7-fold) could clarify the dual potential of D10 as a sustained release system capable of enhancing VAR oral bioavailability.