EVA copolymer matrix for intra-oral delivery of antimicrobial and antiviral agents.

Biocompatible ethylene vinyl acetate copolymer (EVA) was utilized to study the release of an antiviral drug (acyclovir (ACY)) and an antimicrobial drug (doxycycline hyclate (DOH)). Release of both drugs from EVA was measured individually and in combination. The effect of drug combination of DOH and ACY is presented. Additionally, the release rate of DOH after coating of the matrix with a different copolymer, in drug-loading with increasing loads of DOH, and with increases in temperature are also presented. The drugs incorporated in EVA films were prepared from the dry sheet obtained by solvent evaporation of polymer casting solutions with drugs. Drug release from the films was examined for about 12 days in distilled water at 37 degrees C. Changes in optical density were followed spectrophotometrically. The combination of ACY and DOH resulted in an increased release of ACY by about three times (P < 0.001) while DOH showed a decrease in rate of about two times compared to the individual release rates (P = 0.008). Increases in drug levels of DOH resulted in increases in drug release rates (P = 0.001). The release rate of DOH increased with temperature (P = .001; 27, 32, 37 and 42 degrees C were studied) and the energy of activation (DeltaE ( not equal) = 56.69 kJ/mol) was calculated using the Arrhenius equation for the diffusion of DOH molecules. Thus, the release rates of drugs were influenced by many factors: drug combination, coating the device, drug-loading, and temperature variation. Therefore it is proposed that controlling these variables should make it possible to obtain therapeutic levels of drugs released from drug loaded polymer, which may be beneficial in treating oral infections.