Poly(ethylene-co-methyl acrylate) membranes as rate-controlling barriers for drug delivery systems: characterization, mechanical properties and permeability

Poly(ethylene-co-methyl acrylate) (EMA) membranes with different amounts of methyl acrylate (MA) content were studied in terms of the thermal and mechanical properties, swelling and drug permeation. The increase in MA content in the copolymer significantly increased the percentage of elongation and decreased the tensile strength and modulus of elasticity of the membranes. The degree of swelling of the EMA membranes increased with the ethanol composition and MA content. The contact angle of a sessile drop (10 μL of ethanol/water solution) decreased with an increase in the ethanol fraction suggesting that the membrane wettibility increased with the ethanol content. The flux of diltiazem hydrochloride increased from 0.012 to 0.018 mg cm−2 h−1 with an increase in the MA content from 16.5 to 29.0%. By increasing the ethanol fraction from 0.4 to 1.0, the flux of diltiazem hydrochloride into the membranes with 29.0% MA, increased from 2.56 (±0.09)×10−3 to 18.38 (±0.62)×10−3 mg cm−2 h−1. The permeability coefficient increased from 5.85×10−6 to 3.53×10−4 cm h−1 with an increase in the ethanol fraction. The flux can also be correlated with the drug solubility in the membrane and ethanol. For example, the solubilities of diltiazem hydrochloride, paracetamol and ibuprofen were 0.64, 6.68 and 504.48 mg cm−3 in the membrane, respectively. Under the same conditions, the flux for the above mentioned drugs was 0.08 (±0.01), 0.53 (±0.01) and 45.11 (±2.00) mg cm−2 h−1.