Contact lenses (CLs) have emerged as potential ophthalmic drug controlled release systems for a longer drug residence time in the post-lens tear film and a more direct path than topical eye drops. Extensive research is underway to increase residence time and bioavailability of drugs within therapeutic levels on the ocular surface. In this study, we developed a cationic microemulsion-based soft contact lens system for extended delivery of low aqueous solubility drugs. Our drug release kinetic results have shown that cetalkonium chloride (CKC), a commonly-used cationic surfactant, increased the retention of poorly water-soluble drugs in the microemulsion phase of CLs through electrostatic interactions, thus decreasing the drug release rate. In addition, dynamic light scattering (DLS) and transmission electron microscopy (TEM) results suggest the mechanism of extended drug release: CKC not only improves the stability of Brij 97 and Tween 80 based-microemulsions but also decreases the diameter of microemulsion droplets; therefore, more surface area is available for drug adsorption to the oil droplets instead of being dispersed in the hydrophilic phase of the CL matrix. Because CKC also has the potential of enhancing the precorneal residence time of drug molecules between the positively charged oil droplets and the negatively charged corneal epithelium, such cationic microemulsion-based system represents a potential novel device and a new strategy for the controlled ophthalmic delivery of drugs with high bioavailability.

Cationic microemulsion-based soft contact lenses for the controlled delivery of poorly water-soluble drugs

2019 Spring National Meeting

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