Development of sildenafil-loaded orally disintegrating tablet with new lactate salt

Abstract

To develop a sildenafil lactate-loaded orally disintegrating tablet with a faster drug effect onset and immediate action of erection, the orally disintegrating tablets were prepared with various amounts of menthol and colloidal silica using the direct compression technique followed by vacuum drying. Their tablet properties such as friability, hardness, wetting time and disintegration time were investigated. The oral bioavailability of sildenafil in the orally disintegrating tablet was then compared with the sildenafil citrate-loaded commercial tablet (Viagra (R)) in rabbits. Sildenafil lactate was a new salt form with more improved solubility and alleviated bitterness compared with commercial salt, sildenafil citrate. As the amount of menthol in the orally disintegrating tablet increased, the friability increased and hardness decreased, resulting in a shorter wetting time and disintegration time. Colloidal silica did the opposite. The sildenafil lactate-loaded orally disintegrating tablet prepared with 45 mg/tab of menthol and 1.5 mg/tab of colloidal silica gave a hardness of 3-4 KP, friability less than 0.5% and disintegration time less than 30 s, suggesting that it was a practical and commercial product with good tablet property and excellent efficacy. Furthermore, it gave higher AUC and C-max, and shorter T-max values than did the commercial tablet, indicating that it improved the oral bioavailability of sildenafil in rabbits compared with the commercial tablet. Thus, the sildenafil lactate-loaded orally disintegrating tablet might induce a fast onset of action and immediate erection compared with the sildenafil citrate-loaded commercial tablet.