Intraocular penetration

Absorption - Intraocular penetration occurs after topical instillation. Decreased corneal integrity or stromal or uveal inflammation may enhance the penetration into the aqueous humor. Systemic absorption following therapeutic dosing appears negligible. 

Linden and Aim [8] studied the effect of reduced tear drainage on the intraocular penetration of topically applied fluorescein in healthy volunteers. In one eye of each participant both the lower and upper puncta were occluded by the insertion of punctal plugs. A single dose of 20 pL of a 2% solution of sodium fluorescein was instilled in the lower conjunctival sac of both eyes. There was a significant increase in aqueous fluorescein concentrations 1 to 8 h after application of fluorescein in the eye with the occluded puncta, to levels almost four times higher than in the other eye. 

Cremophore EL Cremophore EL, a polyethoxylated castor oil used as a vehicle in various intravenous injections, has also been found to enhance the intraocular penetration of the drugs. Bijl et al. [83] reported that for Cremophore EL (10% and 20%), flux values of cyclosporine A across the fresh cornea were significantly higher than for corneal tissue without the enhancer for the first 16 h of the experiment. Steady-state flux rates were reached for cyclosporine A across the corneal tissue after approximately 2 h in the presence of 10% and 20% Cremophore EL. This observation can probably be explained on the basis of increased aqueous solubility of cyclosporine A in the presence of this emulsifier. Cremophore EL also improved the penetration of cyclosporine A through the epithelial and stromal layers of the cornea [83],... 

Di Colo, G., et al. 2004. Effect of chitosan and of IV-carboxymethylchitosan on intraocular penetration of topically applied ofloxacin. Int J Pharm 273 37. 

Ghelardi, E., et al. 2000. Effect of a novel mucoadhesive polysaccharide obtained from tamarind seeds on the intraocular penetration of gentamycin and ofloxacin in rabbits. J Antimicrob Che-mother 46 831. 

Ghelardi, E., et al. 2004. A mucoadhesive polymer extracted from tamarind seed improves the intraocular penetration and efficacy of rufloxacin in topical treatment of experimental bacterial keratitis. Antimicrob Agents Chemother 48 3396. 

Ghelardi, E., Tavanti, A., Davini, P., Celandroni, F., Salvetti, S., Parisio, E., Boldrini, E., Senesi, S. and Campa, M. (2004) A mucoadhesive polymer extracted from tamarind seed improves the intraocular penetration and efficacy of rufloxacin in topical treatment of experimental bacterial keratitis. Antimicrobial Agents and Chemotherapy 48(9), 3396-3401. 

A potentially beneficial effect of lidocaine has been studied in a randomized, double-blind, placebo-controlled study of the effects of preinstillation of lidocaine on tro-picamide-induced mydriasis (32). Pupillary diameter was significantly increased by the instillation of lidocaine before tropicamide. It was thought that lidocaine can enhance intraocular penetration and hence potentiate the effect of tropicamide. 

Barza M. Factors affecting the intraocular penetration of antibiotics. The influence of route, inflammation, animal species and tissue pigmentation. Scan J Infect Dis 1978 14(suppl) l 51—19. 

All intraocular disorders that require systemic administration or frequent local administration of the drug may be appropriate for these biodegradable systems. Uveitis is a chronic disorder that requires long-term medical therapy. Topical drug treatment is not effective in the treatment of posterior uveitis because of limited intraocular penetration. Systemic administration of corticosteroid or immunosuppressive agents may be effective but are associated with systemic side effects. Sustained drug delivery systems may be effective in the treatment of uveitis. In... 

While systemic delivery of medications does not have associated surgical risks, it may be difficult to achieve adequate intraocular penetration without causing systemic side effects. To minimize systemic toxicity and increase retinal tissue drug levels, local delivery methods to treat and prevent PVR have been investigated. 

In the late 1970s and early 1980s, Peyman and Baum et al. (19,20) popularized the use of intraocular antibiotics and this route of administration became the mainstay of therapy for intraocular infection. Intraocular antimicrobials are now given in essentially all cases of endophthalmitis some patients are also treated with vitrectomy. In the EYS, all patients received intraocular antibiotics but only half the patients received systemic therapy. Systemic antimicrobials did not improve prognosis in the EYS, but amikacin, which has poor intraocular penetration, was used for gram-positive coverage in the study (1). 

Fiscella RG, Gieser J, Phillpotts B, et al. Intraocular penetration of gentamicin after once-daily aminoglycoside dosing. Retina 1998 18(4) 3 39-342. 

Zambito Y, Di Colo G. Chitosan and its derivatives as intraocular penetration enhancers. J Dmg Deliv Sci Technol 2010 20(l) 45-52. 

B V ara U is a newly-developed antiviral drug particularly effective to varicella zoster virus. No changes in the b-wave, the c-wave or the oscillatory potentials were induced by an intravitreal injection of 100 pig BV area U or by intravitreal irrigation with 20 pig/m BV ara U. The concentration of BV ara U after an oral administration was much lower in the vitreous than in the serum, which indicates that intraocular penetration of B V ara U is very poor. Furthermore, an enteral use of B V ara U in conjunction with some of antimetabolites reportedly causes serious systemic adverse effects. Therefore, a topical intraocular application of BV ara U is much preferable. 

F. Tsuji, H. Hikishima, K. Sasaki, and A. Tsuji A, Intraocular penetration of steroid high performance liquid chromatographic determination. Journal of the Eye, 3 396 (1985). 

Brettschneider, L., Prauss, R., Kreja, L. and Havranek, M.,1975. Intraocular penetration of bacitracin and polimyxin B after administration by means of hydrophilic gel contact lenses. Ophthalmol Res. 7 296. 

Jain, M.R. and Lai, S., 1983. Intraocular penetration of carbenicillin, gentamicin and chloramphenicol with Sauflon 85 soft contact lenses. Ind. J. Ophthalmol. 31 645. 

Intraocular Penetration of Fluconazole 1 Hour after Instillation... 

Intraocular Penetration of Fluconazole after Subconjunctival Injection... 

Intraocular Penetration and Ocular Toxicity of Fluconazole 12 Hours after Instillation (Figure 3)... 

The present results demonstrate high intraocular penetration of topically administered fluconazole. Fluconazole concentrations reached maximum levels 15 to 30 min after the final instillationof the 1 hour regimen in the conjunctiva, the cornea, the aqueous humor and the iris-ciliary body. Fluconazole also penetrated well into the sclera and the vitreous humor. High fluconazole concentrations were achieved by the single subconjunctival injection in the RPE-choroid as well as in the sclera, except the anterior ocular segments. Because fluconazole is instilled every 30 min or 1 hour in usual clinical use, we investigated its... 

Yamashita, Y., Mochizuki, K., Torisaki, M., Komatsu, M., Tanahashi, T. and Sakai, H., 1992, Intraocular penetration and effect of fluconazole on the retina. Atarashii Ganka 9 1388... 

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