Development of Fluorimetric Method for Controlled Drug Release From Vinyl Propionate-co-Maleic Anhydride Polymer Modified With Paracetamol

A novel pH-responsive polymeric drug delivery system is developed by covalently binding the active pharmaceutical ingredient paracetamol (PAR) to a synthesized vinyl propionate-co-maleic anhydride (VPR-co-MA) copolymer. The controlled release of PAR from the resulting VPR-co-MA-PAR conjugate was investigated in vitro at various physiological pH values (2.0, 4.5, 7.4, and 9.0) at 37°C over a 6 h-period. A fluorimetric method was utilized to quantify the released PAR, with optimal excitation and emission wavelengths determined to be 330 and 433 nm, respectively. The results demonstrated a distinct pH-dependent release profile. After 6 h, the cumulative drug release was significantly suppressed at acidic gastric pH 2.0 (42.23%), whereas it was substantially higher at neutral and alkaline conditions, reaching 71.29% at pH 7.4 and a maximum of 74.46% at pH 9.0. The pronounced difference in release rates confirms the system's ability to limit premature drug release in the stomach while promoting targeted delivery in the intestinal tract. This VPR-co-MA-PAR conjugate shows significant promise as a carrier for the controlled oral delivery of paracetamol.