The current study aimed to rationally develop and characterize pH-sensitive controlled release hydrogels by graft polymerization of gelatin (Gel) and hydroxypropyl methyl cellulose (HPMC) in the presence of glutaraldehyde (GA) using quetiapine fumarate for the treatment of schizophrenia. The prepared hydrogels discs were subjected to various physicochemical studies including: swelling, diffusion, porosity, sol-gel analysis, Fourier transform infrared spectroscopy, differential scanning calorimetry, and scanning electron microscopy. Three different pH values (1.2, 6.8 and 7.4) were used to determine shape, transition, and controlled release behavior of prepared hydrogels. Various kinetic models including zero order, first order, Higuchi model and Power Law equation were applied on drug release data. The optimized hydrogels were subjected to in vivo studies using albino rabbits. Swelling and release results were found to be insignificant (p < .05) evidencing that there was no significant difference in swelling and drug release rate of hydrogels in different pH mediums. Swelling, porosity, gel-fraction, and drug released (%) were found to be dependent on concentrations of Gel, HPMC, and GA. Kinetic models revealed that QTP-F release followed non-Fickian diffusion. In-vivo studies contributed significantly higher plasma QTP-F concentration (Cmax), time for maximum plasma concentration (Tmax), area under the curve (AUC0-inf) and half-life (t1/2) as 18.32 ± 0.50 µg/ml, 8.00 ± 0.01 hrs, 6021.2 ± 5.09 µg.hrs/ml and 10.06 ± 0.43 hrs, respectively, for test-hydrogels when compared to reference market brand (Qusel® 200 mg, Hilton Pharma, Karachi, Pakistan) QTP-F tablets. It might be concluded that QTP-F loaded pH-sensitive hydrogels were developed successfully with reduced dosing frequency for schizophrenia.
Keywords: Quetiapine fumarate; cross-linking; hydrogels; pH-sensitive; pharmacokinetics.