Ahmed I, Patton T F
Invest Ophthalmol Vis Sci. 1985 Apr;26(4):584-7.
Transcorneal permeation has traditionally been the mechanism by which topically applied ophthalmic drugs are believed to gain access to the internal ocular structures. Relatively little attention has been given to alternate routes by which drugs may enter the eye. A system has been developed which allowed the investigation in vivo of the contribution of noncorneal absorption to intraocular drug levels after topical dosing. Using timolol and inulin as probe drugs, it was shown that the noncorneal absorption route may contribute significantly to drug penetration into intraocular tissues. Furthermore, results demonstrated that drugs absorbed by the noncorneal route appeared to enter certain intraocular tissues by a mechanism which bypasses the anterior chamber. These studies suggested that intraocular penetration via noncorneal routes involves penetration of drug across the conjunctiva/sclera. Neither reentry from the general circulation after drug absorption into the blood or drug delivery by the local vasculature accounted for the observed results. In terms of topical ophthalmic drug delivery, the noncorneal absorption route may be important for drugs that are poorly absorbed across the cornea due to their physical-chemical properties. We have demonstrated this using inulin as a model for a poorly absorbed, high molecular weight substance.
传统上，经角膜渗透一直被认为是局部应用的眼科药物进入眼内结构的机制。对于药物进入眼睛的其他途径，人们相对关注较少。已经开发出一种系统，该系统能够在局部给药后对非角膜吸收对眼内药物水平的贡献进行体内研究。使用噻吗洛尔和菊粉作为探针药物，结果表明非角膜吸收途径可能对药物渗透到眼内组织有显著贡献。此外，结果表明，通过非角膜途径吸收的药物似乎通过一种绕过前房的机制进入某些眼内组织。这些研究表明，通过非角膜途径的眼内渗透涉及药物穿过结膜/巩膜的渗透。药物吸收进入血液后从体循环再进入或局部血管系统的药物递送均不能解释观察到的结果。就局部眼科药物递送而言，非角膜吸收途径对于由于其物理化学性质而难以通过角膜吸收的药物可能很重要。我们已使用菊粉作为吸收不良的高分子量物质的模型证明了这一点。
