| Abstract: | Copolymeric hydrogels of poly(2-hydroxyethyl methacrylate-co-acrylamide) p(HEMA-co-A)] crosslinked with ethylene glycol dimethacrylate, with a high equilibrium degree of swelling (37–65 wt%) in saline solution (NaCl 0.9 wt%) were synthesized as devices for controlled release of cytarabine (ara-C). Two compositions of the copolymer, each with a different degree of crosslinking have been studied, HEMA80/A20 and HEMA60/A40. The antineoplasic drug was included in the feed mixture of polymerization, and discs 3.7 ± 0.4 mm thick and 11.8 ± 0.2 mm in diameter with 5–40 mg (1.0–8.3 wt%) of ara-C were obtained. The diffusion studies followed Fick's second law. The diffusion coefficients for swelling of the gels were between 3.60 × 10?11 and 15.8 × 10?11 m2 s?1; those for release of ara-C were between 0.31 × 10?11 and 7.18 × 10?11 m2 s?1. The activation energies for swelling were in the range 23.4–31.9 kJ mol?1 and those for ara-C release were 42.2–61.6 kJ mol?1; their values indicate that the drug release process depends on drug–matrix and drug–water interactions that are influenced by the aqueous solution content and the network size of the gels. Total release of the drug takes place between 17 h from H60/A40/E2 at 310 K and 6 days from H80/A20/E10 at 288 K. Ara-C degradation was not observed either during loading of the gels or during drug release. © 1999 Society of Chemical Industry |
