Objective: To develop extemporaneous captopril oral solution 1 mg/ml for use in child patients at Songklanagarind Hospital. The formulation was prepared from commercially available 25 mg captopril tablet.
Material and Methods: The formulations were prepared by grinding captopril and vitamin C tablets to a fine powder and adding drinking water (boiled and cooled to room temperature before using) or tap water to the powder resulting in the oral solution containing captopril and vitamin C 1 mg/ml or 5 mg/ml. The oral solutions were stored at room temperature (28 oC -29 oC) and at refrigerated temperature (4 oC). Samples were chosen for analyzed by high performance liquid chromatography (HPLC) to determine the remaining amount of captopril in each preparations on day 0, 7, 14, 21, and 28 respectively. In addition, the study included the stability determination of the ground powder of captopril and vitamin C tablets when stored at room temperature over the same time periods. Captopril in formulations is considered chemically stable if its concentration after storage remains ≥ 90.0% of the initial concentration.
Results: The results showed that the percent labeled amount ±SD of captopril in the formulation prepared by drinking water after 28 days of storage at room temperature and refrigerated temperature were 92.60±0.42% and 97.43±0.94% respectively. The formulation prepared by tap water at room temperature was stable for less than 2 weeks. The percent labeled amount of captopril in ground powder of captopril and vitamin C tablets found to be 91.15±0.32% after storage at room temperature for 28 days. Furthermore, the oral solution prepared from the ground tablet powder of captopril and vitamin C after 4 weeks of the storage was stable for only 1week after addition of drinking water. The pH of all oral solution formulations was found to be less than 4.0
Conclusion: The result from this study indicated that the oral solution prepared from captopril tablet and using vitamin C tablet as antioxidant could be stable for at least 3 weeks if using drinking water in the process of preparation and keeping in the refrigerator.