Purpose: The stability of sildenafil citrate 2.5 mg/mL in two extemporaneously prepared oral suspensions stored at 4 and 25 degrees C was studied.
Methods: Thirty 25-mg tablets of sildenafil citrate were ground to powder, and the powder was combined with a 1:1 mixture of Ora-Sweet and Ora-Plus or a 1:1 mixture of methylcellulose 1% and Simple Syrup, NF, to produce two 2.5-mg/mL suspensions. Five plastic bottles of each suspension were stored in amber plastic prescription bottles at 4 or 25 degrees C. Samples were collected on days 0, 7, 14, 28, 42, 56, 70, and 91 for analysis of sildenafil content by high-performance liquid chromatography; pH was also measured. Samples were visually observed against black and white backgrounds.
Results: The mean concentration of sildenafil citrate exceeded 98% of the initial concentration in all samples at both temperatures throughout the 91-day study period. No changes in pH, odor, or physical appearance were observed.
Conclusion: Sildenafil citrate 2.5 mg/mL in two extemporaneously compounded oral suspensions was stable for 91 days in plastic prescription bottles at 4 and 25 degrees C.