Sildenafil citrate is a
phosphodiesterase-5 inhibitor that is approved by the U.S. Food and Drug Administration for the treatment of
erectile dysfunction. Rapid-dissolving
tablets are relatively novel
dosage forms that can be prepared by extemporaneous compounding and potentially provide unique advantages for medications like
sildenafil. However, such preparations may present newer stability considerations previously unreported. Therefore, the purpose of this study was to assess the physical and chemical stability of sildenafil 100-mg rapid-dissolving
tablets prepared by a commonly practiced molding method, using two different proprietary rapid-dissolving
tablet bases (Medi-RDT or RDTPlus) immediately after preparation and over six months of storage at ambient room temperature. To prepare the rapid-dissolving
tablets, the
powder ingredients were homogeneously mixed, filled, and compressed into a 96-cavity
metal mold. The formulation was then heated at 110°C for 10 minutes in the mold, released from the mold, and cooled at room temperature for 15 minutes. The prepared
tablets were packaged in
amber-colored
blister packs with cold-adhesive backing seals and stored at ambient room temperature. At predetermined time points, rapid-dissolving
tablets of each formulation were retrieved to perform stability analyses. These analyses included weight variation, breaking force, disintegration, friability, and potency via high-performance liquid chromatography following the United States Pharmacopoeia methods and visual inspection. At time 0 (immediately after preparation), the results of the tests for rapid-dissolving
tablets made with Medi-RDT base v. RDT-Plus base were as follows: average
tablet weight (649.7 mg v. 753.6 mg); breaking force (24.01 N v. 32.34 N); friability (8.52% v. 7.55%); disintegration time (34 seconds v. 35 seconds); and potency (98.61% v. 101.41%), respectively. Over the six-month storage period, both formulations of rapid-dissolving
tablets had no significant changes in visual appearance,
tablet weight, breaking force, or disintegration time. High-performance liquid chromatographic-based
tablet assays for both formulations were consistently above 95% label claim at each time point, with no chromatographic evidence of degradation. Thus, the studied formulations of compounded
sildenafil 100-mg rapid-dissolving
tablets prepared using both Medi-RDT or RDT-Plus were found to be physically and chemically stable over six months of storage at ambient room temperature.