Prodrug design is a choice of approach in solving many of the stability, solubility, permeability and targeting problems that plague drug discovery and development. The prodrug approach has the ability to keep promising new drug candidates alive through development and improving the safety and efficacy of existing drug products. It is effective for drugs suffering from undesirable side effects. A mutual prodrug normally comprises of two biologically active agents coupled together so that each acts as a pro-moiety for the other agent. The carrier may have synergistic effect or it may have some additional pharmacological properties. lacking in the parent drug.