Preformulation studies on the development of a transdermal therapeutic system with captopril

The article presents the results of a study of the process of captopril penetration through a semipermeable membrane by in vitro dialysis to practically confirm the possibility of its use for creating new forms of delivery – transdermal therapeutic systems (TTS). The aim: Preformulation studies of pharmaceutical development of a transdermal dosage form of TTS with antihypertensive action with captopril, determination of the nature and kinetic parameters of the process of captopril permeability through a semipermeable membrane in vitro, as well as the influence of the initial concentration of the selected active pharmaceutical ingredient (API) on this process. Materials and methods: At the initial stage of development of antihypertensive TTS, the in vitro process of captopril permeability through a semi-permeable membrane by dialysis was investigated at (37±0.5) °C. A phosphate buffer solution (pH 7.4) was used as a diffusion medium. The initial concentration of captopril in the donor solution was 30 mg/ml. Results: Based on the analysis of the obtained experimental values of the amount of the studied substance in the sample of dialysate Хi and the specific flux gradient per unit of time ΔQt it was noted that the process of captopril permeability in model conditions is characterized by a uniform rate and corresponds to zero-order kinetics. The high value of the correlation coefficient R = 0.9996 for the obtained kinetic equation confirms the linear dependence of passage through the membrane of the studied substance on time. Conclusion: Studies conducted to determine quantitative permeability characteristics have shown, first, the ability of molecules of the selected substances to overcome membrane barriers and allow a positive assessment of the acceptability of this active pharmaceutical ingredient as attractive for the creation of TTS