Cataplasm-based controlled drug delivery: Development and optimization of a novel formulation

The objective of the present study was to study the formulation variables involved in the development of a novel plasterlike preparation (cataplasm) and to optimize important formulation variables with an aim to maximize the in vitro release of the drug with minimum lag time. Cataplasm was prepared by dispersing a model drug (ibuprofen), humectant (glycerol), adhesive (Indopol H100(R)), polymer (Carbopol C934P(R)) with other formulation ingredients in a beaker with an open-blade impeller. The paste was cast on a nonocclusive backing membrane and dried overnight. The diffusion of the model drug was studied across a cellulosic membrane using Franz's diffusion cells. The amounts of three formulation variables, carbopol (X-1), glycerol (X-2), and indopol (X-3) were studied at three levels, and a face-centered cubic design was used to maximize the flux. An optimization procedure for maximum flux and minimum lag time predicted a flux of 97.22 mcg/cm(2)/hr at X-1 (2% w/w), X-2 (11.75% w/w), and X-3 (6% w/w). An experimental patch prepared with the above concentrations yielded a flux of 90.7 mcg/cm(2)/hr.