Formulation factors influencing the release of clonazepam from a carbopol hydrogel

A study of formulation factors influencing the release of clonazepam from a Carbopol hydrogel through a cellulose nitrate membrane impregnated with lauryl alcohol was performed using two diffusion cell assemblies. The formulation variables were the cosolvent effects of propylene glycol and polyethylene glycol of different molecular weights in aqueous solutions of various composition. The gel formulation phenomenologically behaves as a zero-order release system, although the diffusion controlled mechanism may also be operative. The results showed that both methods were practically equivalent in terms of drug release profile and total drug released allowing the best formulation to be found.