Abstract
Purpose: :
A transdermal ocular drug delivery system has been developed. After applying the transdermal patch on the eyelid skin, the drug concentration in various eye tissues has been measured in vivo in rabbits. The concentration in various eye tissues including the conjunctive, tear and plasma was measured. The in vivo concentration was then compared with the calculated profiles on the basis of the modified cylindrical diffusion model for ocular pharmacokinetics. The in vivo tear concentration after eyelid penetration agreed with the in silico evaluation.
Methods: :
Radioactivity concentrations in ocular tissues were measured after single eyelid transdermal administration of Ketotifen 4% patch to male rabbits. The tissue concentrations including plasma, tear, conjunctiva, eyelid skin, cornea, aqueous humor, lens, vitreous body, were measured at 2,4,8,12,16, 24, 72 and 168 hours after the patch application. The experimental concentrations were then compared with the calculated profiles based on the diffusion-partition model.
Results: :
The drug molecules were effectively delivered to the ocular tissues such as the conjunctive and the tear locally after eyelid skin penetration. Although the drug molecules penetrated through the eyelid skin is much less than the systemic delivery (approximately 5%), the ocular bioavailability becomes higher due to the small volume of distribution. By applying the mathematical model for ocular pharmacokinetics, the concentration-time profiles in various eye tissues were well predicted after the transdermal ocular delivery.
Conclusions: :
A new ocular drug delivery system, applied on the eyelid skin, is a promising method to improve the local bioavailability for treating a variety of eye diseases. The topical bioavailability for the patch was found to be much higher than that after systemic circulation.