Rapid-Onset Sildenafil Sublingual Drug Delivery Systems: In Vitro Evaluation and In Vivo Pharmacokinetic Studies in Rabbits
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The aim of the present study was to prepare sublingual delivery systems for sildenafil and evaluate its relative bioavailability after sublingual administration in rabbits to attain a rapid onset of action with good efficacy at lower doses. For sublingual application, sildenafil and its citrate were formulated in 2 different dosage forms: the first was a sublingual spray consisting of sildenafil in 2 microemulsion systems, oleic acid or propylene glycol (PG), and the second was sublingual tablets prepared with various granulated sublingual sprays adsorbed onto a silicate adsorbant (Florite® R), binders (Cyclocel® or EMDEX®), and disintegrants (Ac-Di-Sol® or Kollidon® CL).
Results showed that sublingual absorption of sildenafil spray prepared with PG was fairly rapid. At a 0.5-mg dose, the mean onset of action was 1.3 ± 0.6 min and lasted for about 1.5 h according to the pharmacokinetic studies. In vivo studies also showed that for sublingual tablets formulated with sildenafil in PG adsorbed onto Florite® R at a 1:1 weight ratio then mixed with Cycloel® and Ac-Di-Sol®, the onset action was fast at 1.9 ± 0.4 min and lasted for about 1 h at 0.5 mg. These findings suggest the potential for the sublingual delivery of sildenafil instead of the conventional oral administration.
Keywords: sildenafil; erectile dysfunction; sublingual tablets; sublingual spray; bioavailability; excipient
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1 School of Pharmacy, College of Pharmacy, Taipei Medical University, Taipei 110, Taiwan, ROC
2 Department of Cosmetic Science, Providence University, Taichung City, Taiwan, ROC
3 Department of Cosmetic Science and Management, Mackay Medicine, Nursing and Management College, Taipei, Taiwan, ROC