Long-term stability of extemporaneously prepared captopril oral liquids in glass bottles.

PURPOSE: The long-term stability of captopril in extemporaneously prepared oral liquids was studied. METHODS: Captopril solutions of 1 and 5 mg/mL were prepared in sterile water for irrigation with sorbitol, disodium edetate, and sodium benzoate. The samples were stored in 100-mL amber glass bottles with a headspace of air at 22 degrees C for 12 months. The captopril concentration was determined by high-performance liquid chromatography at 0, 3, 6, 9, and 12 months. The pH of the solutions was also measured, and the physical appearance was recorded. The stability of the 1-mg/mL captopril preparation during 1 month of simulated use when stored at 2-8 degrees C was tested at the start and the end of the 12-month study period. Chemical stability was defined as retention of at least 90% of the initial captopril concentration. The microbiological quality of the preparations was tested at 0, 6, and 12 months (1 mg/mL) and 0 and 12 months (5 mg/mL). RESULTS: Throughout the 12-month study period, the captopril concentration in the oral liquids exceeded 90% of the initial concentration. The lowest concentration (98.5%) was detected in the 5-mg/mL preparation after 3 months of storage. The 1-mg/mL preparation was stable during 1 month of simulated use, both at the start and the end of the 12-month study period. No microbiological growth was observed in any of the samples tested. CONCLUSION: Extemporaneously prepared oral liquid formulations of captopril 1 and 5 mg/mL were chemically stable when stored in glass bottles at room temperature for 12 months when stabilized with 0.1 mg/ mL disodium edetate at a low pH.

Evaluation of different formulation studies on air-filled polymeric microcapsules by multivariate analysis.

Air-filled polymeric microcapsules have been prepared by freeze-drying of emulsions containing the wall-forming polymer in the organic phase of oil in water emulsions. Echogenic air-filled microcapsules were prepared from emulsions containing either (-)-camphene, cyclohexane or cyclooctane as the solvent in the organic phase. Formulation studies have been performed to improve the yield and acoustic quality of the microcapsule suspensions. The yield was measured as particle concentration or efficacy, i.e. normalised attenuation at 3.5 MHz, related to the amount of polymer used. No overall conclusion could be made for all the variables when visually comparing the results from the different investigations. Multivariate analyses (PCA and PLS) were therefore necessary to be able to reveal any relevant systematic information from all the investigations. Different parameters describing the formulation, the production process and parameters describing the characterisation of the intermediates and the final product were set as independent X-variables. Three to four percent (w/v) of polymer was found to be the appropriate concentration of wall forming polymer. Including PEG 3000 resulted in improved freeze-dried product and suspension. Quenching of the emulsions by freezing in dry ice/methanol prior to freeze-drying was not necessary. Process parameters for homogenising and freeze-drying should be optimised with regard to the single systems, due to the different physico-chemical properties of the different solvents, especially melting point and vapour pressure.