Improved Ocular Drug Delivery: A Prodrug Approach

Topical application of eyedrops has been mainly used for treatment of ocular diseases. After instillation of an eyedrop, less than 5% of the applied dose reaches the intraocular tissues. Rapid loss of the instilled solution from the precorneal area and poor cornea1 penetration of the drug results in low ocular bioavailability. However, ocular absorption of a drug can be improved by increasing its lipophilic properties. Prodrug derivatization is a suitable approach to achieve the desired goal. But unfortunately, stability and solubility problems in the resulting compounds as well as local irritation have limited their efficacy and clinical acceptability. This review summarizes the application of prodrugs designed to improve the ocular activity and to minimize the systemic and local toxicity of ocular drugs.