Intraocular penetration of topically administered acyclovir

Area of Science:

• Ophthalmology
• Pharmacokinetics
• Drug Delivery

Background:

• Herpetic keratitis is a significant ocular infection.
• Effective drug delivery to the cornea and aqueous humor is crucial for treatment.
• Acyclovir is a primary antiviral agent used for herpes simplex virus infections.

Purpose of the Study:

• To quantify the aqueous and intracorneal concentrations of acyclovir.
• To compare the penetration of acyclovir via ophthalmic ointment versus subconjunctival injection.
• To evaluate the clinical utility of different acyclovir administration routes for ocular infections.

Main Methods:

• High-performance liquid chromatography (HPLC) was used for drug quantification.
• Acyclovir was administered to rabbit eyes as a 3% ophthalmic ointment and a 1.5% subconjunctival injection.
• Drug concentrations were measured in aqueous humor and corneal tissue at various time points.

Main Results:

• Ophthalmic ointment yielded maximum concentrations of 3.38 µg/ml in aqueous humor and 45.78 µg/ml in the cornea.
• Subconjunctival injection resulted in higher maximum concentrations: 15.32 µg/ml in aqueous humor and 111.97 µg/ml in the cornea.
• Both methods demonstrated drug penetration, with subconjunctival injection showing superior levels.

Conclusions:

• Subconjunctival acyclovir administration leads to significantly higher ocular drug concentrations compared to ophthalmic ointment.
• High corneal drug levels achieved via ointment may still be clinically relevant.
• Subconjunctival administration is a promising route for treating severe herpetic keratitis due to enhanced drug delivery.