Effect of Asparagus racemosus extract on transdermal delivery of carvedilol: a mechanistic study.

This study was designed for investigating the effect of Asparagus racemosus (AR) extract and chitosan (CTN) in facilitating the permeation of carvedilol (CDL) across rat epidermis. Transdermal flux of carvedilol through heat-separated rat epidermis was investigated in vitro using vertical Keshary-Chien diffusion cells. Biophysical and microscopic manifestations of epidermis treated with AR extract, CTN, and AR extract-CTN mixture were investigated by using differential scanning calorimetry, transepidermal water loss, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Biochemical estimations of cholesterol, sphingosine, and triglycerides were carried out for treated excised as well as viable rat epidermis. The antihypertensive activity of the patches in comparison with that of oral carvedilol was studied in deoxycorticosterone acetate-induced hypertensive rats. The permeation of carvedilol across excised rat epidermis was significantly higher (p < 0.05) when AR extract, CTN, or AR extract-CTN mixture was used as donor vehicle as compared to propylene glycol/ethanol (7:3) mixture. Epidermis obtained after 12 h treatment of viable rat skin with AR extract-CTN mixture showed significantly higher (p < 0.05) permeability to CDL as compared to that after treatment with AR extract or CTN alone. Further, the application of patches containing AR extract-CTN mixture resulted in sustained release of CDL which was able to control the hypertension in deoxycorticosterone acetate-induced hypertensive rats through 36 h. Estimation of micro constituents in rat epidermis revealed maximum extraction of cholesterol, sphingosine, and triglycerides after treatment with AR extract-CTN mixture. This was manifested in altered lipid and protein-specific thermotropic transitions. Further, increase in intercellular space, disordered lipid structure, and corneocyte detachment as observed in SEM and TEM suggested great potential of AR extract for use as percutaneous permeation enhancer. The developed transdermal patches of CDL containing AR extract-CTN mixture exhibited better performance as compared to oral administration in controlling hypertension in rats.