Extended Stability of Morphine and Sildenafil for Oral Use in Infants and Young Children.

Morphine and sildenafil are commercially available at high concentrations which may lead to errors in measuring small volumes to provide low doses needed in infants. The purpose of this study was to assess the stability of morphine sulfate and sildenafil citrate in extemporaneously prepared suspensions for oral use. Morphine (0.2 mg/mL) was prepared from dilution of morphine elixir (2 mg/mL) with distilled water and stored in amber, plastic syringes at 25°C for 60 days. The mean concentration of morphine exceeded 95% of the initial concentration for the entire 60-day study period. No marked changes in pH or physical appearance were observed. Sildenafil (2.5 mg/mL) was prepared from Revatio tablets in two groups of suspensions: one group in 1% methylcellulose:simple syrup (1:7) and another in OraPlus:OraSweet (1:1). These were stored in plastic prescription bottles at 4°C and 25°C for a period of 91 days. The mean concentrations of sildenafil exceeded 95% of the original concentrations throughout the 91-day study period. No substantial changes were seen in the pH or physical appearance of the suspensions. These results indicate that the diluted morphine was stable for at least 60 days at room temperature. In addition, sildenafil was stable for 91 days in each of the two suspensions prepared from Revatio tablets and stored under refrigeration or at room temperature.