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Updated: Jun 27, 2026
Use of Rabbit Eyes in Pharmacokinetic Studies of Intraocular Drugs
Published on: July 23, 2016
Determination and pharmacokinetic profile of liposomal foscarnet in rabbit ocular tissues after intravitreal
Carmen Claro1, Rosa Ruiz, Elisa Cordero
1Departamento de Farmacia y Tecnología Farmacéutica, Facultad de Farmacia, Universidad de Sevilla, Sevilla, Spain.
Abstract:
The treatment of ocular diseases affecting the posterior segment of the eye, such as cytomegalovirus (CMV) retinitis, requires the access of the drugs to the vitreous humor. Foscarnet inhibits replication of herpesviruses, including CMV. The drug's encapsulation in liposomes is meant not only to increase activity and to prolong the effect of the drug, but also to reduce its toxicity. The aims of the present study were to evaluate foscarnet levels and its pharmacokinetic parameters in vitreous humor and retinal tissue of rabbits after the administration of an intravitreal injection of both liposomal foscarnet and foscarnet commercial solution. Liposomes were prepared by the reverse-phase evaporation method. The amount of encapsulated foscarnet (F) was 63% wt. The in vitro diffusion assays showed that F was released more slowly when formulated in liposomes than in the commercial solution. The in vivo studies showed that, as opposed to commercial solution F, liposomal F achieves stable and durable therapeutic levels in retina, going beyond 72h, reaching the vitreous humor with adequate levels to accomplish the aims of intravitreal therapy. Lyophilization also increased stability and dispersion of liposomes in aqueous medium, although not improving the pharmacokinetic results over those from non-lyophilized liposomes.
Insights
Liposomal foscarnet achieves sustained therapeutic drug levels in the eye for treating cytomegalovirus (CMV) retinitis. This enhanced delivery method ensures prolonged drug presence in the vitreous humor and retina.
Area of Science:
- Ophthalmology
- Pharmacology
- Biotechnology
Background:
- Ocular diseases like cytomegalovirus (CMV) retinitis require effective drug delivery to the posterior eye segment.
- Foscarnet is an antiviral agent effective against CMV, but its therapeutic application is limited by delivery challenges.
- Liposomal encapsulation aims to improve drug efficacy, duration, and safety for ocular treatments.
Purpose of the Study:
- To evaluate foscarnet concentrations and pharmacokinetics in rabbit vitreous and retinal tissues.
- To compare intravitreal injections of liposomal foscarnet versus a commercial foscarnet solution.
Main Methods:
- Liposomes containing foscarnet were prepared using the reverse-phase evaporation method.
- In vitro diffusion assays assessed drug release profiles.
- In vivo intravitreal injections in rabbits were used to determine pharmacokinetic parameters.
Main Results:
- Liposomal foscarnet demonstrated slower in vitro drug release compared to the commercial solution.
- In vivo studies showed liposomal foscarnet achieved stable, durable therapeutic levels in the retina exceeding 72 hours.
- Adequate foscarnet levels were reached in the vitreous humor for effective intravitreal therapy.
Conclusions:
- Liposomal foscarnet offers a promising strategy for sustained drug delivery in the posterior eye segment.
- This formulation overcomes limitations of commercial solutions, providing prolonged therapeutic effects for ocular diseases like CMV retinitis.
- Lyophilization enhanced liposome stability but did not further improve pharmacokinetic outcomes.
