Investigation of cyclobenzaprine hydrochloride release from oral osmotic delivery systems containing a water-swellable polymer.

Oral osmotic delivery systems containing polyethylene oxide (PEO, a water-swellable polymer) were designed and the release of cyclobenzaprine hydrochloride (model drug) from the devices was investigated. The systems consisted of model drug, mannitol (osmotic agent), and increasing amounts of PEO surrounded by a semipermeable membrane drilled with a delivery orifice. There was a decrease in drug release rate with PEO in the core. This may be due to solubility-modulating properties of the polymer. Visual inspection of the devices with PEO showed significant swelling during dissolution testing. Swelling (internal pressure) may influence water inhibition rate into the core and subsequently drug release rate. The release rates were a function of membrane thickness. The release rates were independent of orifice size (range of 150-510 microns diameter) and hydrodynamic conditions for the devices. This would be advantageous in the delivery of drugs in man.