In vitro drug release studies of 2-hydroxyethyl acrylate or 2-hydroxypropyl methacrylate-4-{(1E,4E)-5-[4-(acryloyloxy)phenyl]-3-oxopenta-1,4-dienyl}phenyl acrylate copolymer beads.
4-{(1E,4E)-5-[4-(Acryloyloxy)phenyl]-3-oxopenta-1,4-dienyl}phenyl acrylate (APPA) was synthesized by reacting (1E,4E)-1,5-bis(4-hydroxyphenyl)penta-1,4-dien-3-one (HPD) and acryloyl chloride using triethylamine as a base. 2',4-Dichloro-5'-fluoro-1-ene-2-(4-hydroxyphenyl)phenone (EHP) (Arun A, Reddy BSR, Rajkumar M. Polymeric drug for antimicrobial activity studies: Synthesis and characterization. J Bioact Compat Polym 2003;18:219) was used for the controlled release studies. Two types of porous hydrogels were prepared by copolymerizing 2-hydroxyethyl acrylate (HEA) or 2-hydroxypropyl methacrylate (HPMA) with APPA (as a crosslinker) by employing the suspension polymerization technique. The morphology of the hydrogels were characterized by the optical microscopy (OM) and scanning electron microscopy (SEM). Different variations were employed in the preparation of hydrogels to study the effect of crosslinker percentage and drug the loading percentage. Totally 18 types of hydrogels were prepared. The drug-releasing pattern was monitored over a period of 4 weeks using the UV spectroscopic technique by measuring the absorptions at 330.5 nm. In vitro release experiments were carried out at pH 7.4 and pH 9.2. In total, 36 releasing experiments were conducted. The results showed that the controlled release of the drug was dependent on the monomer (HEA or HPMA), crosslinker percentage (CLP), drug-loading percentage (DLP), and pH. The release rate was higher for HEA-based hydrogels when compared with HPMA-based hydrogels in all compositions. The release rate was noticeably higher in pH 9.2 than pH 7.4.