Abstract
Purpose Captopril is one of the most important angiotensin converting enzyme inhibitors and still the gold standard for the treatment of hypertension and congestive heart failure. However, it has a short duration of action and about 1-2 h biological half-life. Formulation of a sustained release dosage form of captopril is difficult due to its instability at the alkaline pH of the gastrointestinal tract. Therefore, incorporation of captopril within bioadhesive cubic nanoparticles or cubosomes could be an alternative way to improve its efficiency. Methods Monoolein dispersions containing captopril were prepared by the homogenization technique using different concentrations of monoolein and poloxamer. Characterization of these dispersions was performed by measuring particle size, small angle X-ray diffraction, cryo transmission electron microscopy, entrapment efficiency, and in-vitro release of captopril. Results Monoolein cubic nanoparticles with mean particle sizes between 250 and 350 nm were obtained after autoclaving the homogenized dispersions. The cubic structure was confirmed by the presence of the three characteristic X-ray diffraction peaks of P-type cubic phase and from cryo transmission pictures. A slow release of captopril from cubosomes was observed within 8 h with a high bioadhesion capacity where about 75% of these cubosomes adhered to stomach tissues. Conclusion Monoolein cubosomes could be used successfully as carriers for captopril where they slowly released it and had a good adhesion property to stomach tissues.