Solubility of polymer in gastric fluid and the solvent employed for administration of the formulation are to be considered in design of controlled drug delivery systems. The polymer with least solubility in these fluids avoids the possible dose dumping. pH independent polymers and pH dependent polymers soluble in intestinal polymers are preferable to prevent the dose dumping risk. Diffusion controlled systems are preferable compared to dissolution controlled systems go prevent dose dumping. Matrix controlled system are best suited rather than membrane controlled systems.