Investigation of critical core formulation and process parameters for osmotic pump oral drug delivery

Push-pull osmotic pump (PPOP) tablets of a practically insoluble model drug were developed and the effect of various formulation and process parameters on tablet performance was evaluated in order to identify critical factors. The formulation factors such as the viscosity grade of polyethylene oxide as the primary polymer as well as the level and location of osmogen within the bilayer tablets led to a difference in performance of osmotic tablets and hence should be critically evaluated in the design of such dosage forms. Modification of granulation process, i.e., the granulating liquid composition or drying method of granules, did not impact the drug release from the osmotic tablets at the evaluated scale of this study. The influence of varying dose and aqueous solubility of other model drugs (i.e., theophylline, acetaminophen, and verapamil HCl) on the developed PPOP template was also investigated. Results showed that irrespective of the perceived complexity of development and manufacturing of osmotic pumps, the osmotic tablets in this study demonstrated a robust and yet flexible platform in accommodating different types of drug candidates, regardless of solubility, for the dose levels below 25% w/w of the pull layer formulation.