Pharmaceutical challenges and perspectives in developing ophthalmic drug formulations

Ocular drug delivery has been widely recognized as an attractive route for drug administration for cures of ocular diseases. Overall, designing an effective therapy to cure ocular diseases has been considered as a formidable task. Even though some infectious or inflammatory eye diseases could be alleviated by eye drops or ointments, achieving the required therapeutic efficacy along with ocular bioavailability remains a challenge due to the numerous anatomical and physiological barriers prevailing in the eye. Drug delivery to the posterior segment of the eye is yet a more challenging task. In this context, a better understanding of physiologic natures of the eyes and ocular pharmacokinetics would facilitate the development of new drug delivery systems to treat various vision-threatening disorders. For the effective drug delivery to target sites and to enhance the ocular bioavailability, recent progress in formulation strategies using nanotechnologies holds promises in terms of devising improved ophthalmic medicines. Hence, this review presents an overview of various aspects of ocular drug delivery, with a specific emphasis on nanocarrier-based strategies, including physiological barriers in eyes and conventional drug formulations. Recent research on sustained, controlled, and targeted systems for ocular drug delivery was updated as well.