Release characteristics of quinupramine from the ethylene-vinyl acetate matrix.

An ethylene-vinyl acetate (EVA) matrix containing quinupramine was prepared in an attempt to develop a controlled delivery system for quinupramine. Permeation studies of quinupramine through the EVA copolymer membrane were carried out using a two-chamber diffusion cell. The rate of drug permeation through the EVA membrane was proportional to the PEG 400 volume fraction. The release of quinupramine from the EVA matrix was examined using a modified Franz diffusion cell. A plasticizer was added to prepare the pore structure of the EVA matrix in order to increase the rate of drug release. The effects of PEG 400, membrane thickness, drug concentration, temperature, and plasticizer on drug release rate were investigated. The drug release rate from the EVA matrix increased with increasing PEG 400 volume fraction, temperature and drug loading dose. The activation energy for drug release was 5.91, 5.39, 4.68 and 4.52 kcal/mol for a loading dose of 0.5%, 1%, 1.5%, and 2%, respectively. Among the plasticizers used, diethyl phthalate showed the best results. The release of quinupramine from the EVA matrix follows a diffusion-controlled model, where the quantity released per unit area is proportional to the square root of time. The controlled release of quinupramine was achieved using the EVA polymer including a plasticizer.

Development and biopharmaceutical evaluation of quinupramine-EVA matrix containing penetration enhancer for the enhanced transdermal absorption in rats.

To increase the skin permeation of quinupramine through the rat skin, different types of enhancers were added to an ethylene-vinyl acetate (EVA) matrix containing 2% quinupramine. The effects of the enhancers on the level of quinupramine permeation through the skin were evaluated by using Franz diffusion cells that were fitted with the intact excised rat skin. Among the enhancers used, which included fatty acids (saturated and unsaturated), glycerides, pyrrolidones, and nonionic surfactants, polyoxyethylene-2-oleyl ether showed the best enhancement. The pharmacokinetics and bioavailability of quinupramine from an EVA matrix were examined to determine the level of percutaneous absorption in rats. The percutaneous absorption of quinupramine from the EVA matrix with or without an enhancer was investigated. Quinupramine was administered orally or intravenously to compare the pharmacokinetic parameters with that of the transdermal route. The relative bioavailability of quinupramine in the matrix containing polyoxyethylene-2-oleyl ether as an enhancer was approximately 2.81 times higher than the group without an enhancer. Histological examination revealed that the skin pretreated with the EVA matrix containing the enhancers had a loosely layered stratum corneum. These results show that the quinupramine-EVA matrix containing a permeation enhancer could be a good transdermal delivery system for providing sustained plasma concentrations.