ABSTRACT
An efficient delivery system to afford maximum therapeutic efficacy and promote patient compliance remains an unmet medical need for many ophthalmic drugs. Due to arrival of many hydrophilic drugs in the market with poor ocular bioavailability (as a result of eye’s unique protective anatomical barriers, charges present over drugs, low residence time and poor permeability nature) the researchers are finding it challenging to formulate them into a suitable dosage forms with required efficacy and patient compliance. With the advent of many hydrophilic drugs in the market and their low bioavailability as a result of eye’s unique protective anatomical barriers, charges present, low residence time, and poor permeability, the researchers are finding it challenging to formulate them in suitable dosage forms. The present chapter explains the basic concepts and applications of colloidal nanoparticles (NPs) as an answer to the above-mentioned problems, and strategies for effective drug delivery to the eye. However, the poor physical entrapment of hydrophilic drugs into NP lipophilic matrix remains a challenge and resulted in high polymer/lipid instillation, indicating potential ocular toxicities. Thus, in this chapter, the concept of development of carrier–drug conjugates and their NPs for improved loading of the hydrophilic drugs is briefed. Further, NPs are reported to have poor ocular residence time, almost similar to eye drops. Therefore, various approaches used to improve the ocular residence time of nanoparticulate hydrophilic drugs are explained with available case studies followed by a brief discussion on advanced and future strategies that can be used for the efficient ocular delivery of drugs. Finally, we have explained the regulatory, clinical and future perspectives relating to the concept of ocular delivery of plain drugs, nanoparticulate drugs and other advanced approaches.
