Formulation and Characterisation of Cilnidipine Microsponge Loaded Hydrogels for Antihypertensive Activity

Owing to presystemic metabolism following oral drug delivery, most antihypertensive medications have a low bioavailability. Cilnidipine is a calcium channel blocker used to treat mild to moderate hypertension. Cilnidipine's bioavailability is reduced by 13% due to substantial presystemic metabolism. The study aimed to fabricate non-irritant and stable microsponge-based hydrogel to enhance the bioavailability of cilnidipine, a weakly water-soluble medication. In addition, the goal was to enhance the permeation rate and retention time at the site of application. Formulation was developed by using a two-level factorial design with Design Expert software version 13 (14-day free trial). Microsponges were formulated by the emulsion solvent diffusion method, followed by evaluating responses, such as particle size, percentage entrapment efficiency, in vitro drug release, and surface morphology. In addition, X-ray diffraction (XRD) and fourier transform infrared spectroscopy (FT-IR) were performed. Viscosity, swelling behaviour, spreadability, in vitro diffusion, skin irritancy using Wistar albino rats, and in vitro permeation using goat skin were assessed, and stability studies were performed after incorporating the finest formulation into the gel base. Fabricated microsponges were found to be within the required micro dimensions having the necessary porous morphology as demonstrated by scanning electron microscopy studies. Drug entrapment efficiency was found to be in the range of 75-88%. The extended medicament release duration of up to 8 hours was observed. The diffusion data showed controlled release, as demonstrated by Higuchi’s plot. In vitro permeation studies displayed enhanced medicament retention and permeation rate at the site of application. The fabricated microsponge drug delivery system was found to be stable, non-irritant, and having enhanced permeation rate and retention time.