Effect of N-methyl-2-pyrrolidone on the skin permeation of estradiol and levonorgestrel from adhesive strips prepared using Eudragit EPO

Wc developed a system to incorporate drugs in an Eudragit EPO adhesive polymer matrix under aqueous conditions. Estradiol (E2) and levonorgestrel (LNG), which possess poor water solubility, were dissolved in N-metliyl-2-pyrrolidone (NMP) and added to the solution of polymer, succinic acid, and trietliyl citric acid. The solution was distributed on a backing sheet and dried at 80 °C for 10 mill. NMP volatilized during the drying process, however E2 and LNG dissolved in the polymer matrix maintaining a supersaturated state. Preparation of the adhesive matrix without NMP resulted in extensive crystallization of the drugs. Permeation of drug from the tape prepared with NMP was 3 ~ 4 times greater than that from tape prepared without NMP. An adhesive strip containing 2.5% E2 or LNG permeated about 7 and 5 μg drug/cm2, respectively, within 24 h. Permeation behavior of drugs from adhesive strips containing both drugs was similar to that from strips containing each drug.