The prolonged release of oxytetracycline hydrochloride from ethylcellulose microcapsules

Oxytetracycline hydrochloride microcapsules were prepared by separation of ethylcellulose from cyclohexane solution following cooling. Incomplete release was found when testing the dissolution rate in water. Interaction of the polymer with oxytetracycline was elucidated by IR spectroscopy. More release of the drug in water agreed with the diffusional model, but in acid it was more complex.