Dual Drug Loaded Bilayer Hydrogel Coated with Citric Acid for the Treatment of Dry Mouth Syndrome

The objective of the present study is to formulate the bilayer hydrogel of Aceclofenac and Itraconazole followed by surface spray coating with citric acid to treat inflammation, oral candidiasis, and xerostomia conditions in HIV patients. The hydrogel was prepared by the chemical cross-linking method using polyvinyl alcohol as polymer at the concentrations of 3%, 5%, 7%, and 9% w/v, for both the individual drugs and the combination bilayer. The amount of cross-linking agent (glutaraldehyde 1% v/v) and the catalyst (concentrated hydrochloric acid [HCl], dilute HCl, and acetic acid) was optimized at the level of 0.1 mL each in every hydrogel system, based on the required physical properties. The hydrogels were subjected for various evaluation parameters like weight variation (0.054–0.300 g), diameter (9.5–12.5 mm), thickness (2.5–4.0 mm), drug content (2.5–2.8 mg/mL), and swelling study. The increase in the polymer composition had led to a significant increase in the thickness and weight of the hydrogel and a corresponding decrease in the swelling index. Other characterization techniques like Fourier Transform Infra-Red Spectroscopy, X-Ray Diffraction, ThermoGravimetry—Differential Scanning Calorimetry, and optical microscopy analysis were carried out to study physicochemical interactions, crystallinity, thermal, and surface properties of the optimized hydrogel, respectively. The in vitro drug release studies by United States Pharmacopeia dissolution basket model and ex vivo permeation studies using Franz diffusion cell with goat buccal skin were carried out for 6 h, in different media such as distilled water, phosphate buffer pH 6.8, and simulated salivary fluid.