Pharmacokinetics of ganciclovir eye drops: a comparative study of solutions prepared from ganciclovir for intravenous infusion and ganciclovir gel.

Purpose: To evaluate the pharmacokinetics of ganciclovir eye drops by comparing solutions prepared from ganciclovir for intravenous infusion and ganciclovir gel and to assess the impact of systemic administration on drug levels in ocular tissues and serum.

Study design: Experimental study design.

Methods: Ganciclovir solutions (0.5% and 1.0%) prepared by diluting DENOSINE ^® IV Infusion in saline and 0.15% ganciclovir gel (Virgan^®) were topically administered in rabbit eyes, with and without concomitant systemic administration of ganciclovir. The concentrations of ganciclovir in the corneal epithelium, stroma, and endothelium, aqueous humor; and blood plasma were analyzed by high-performance liquid chromatography (HPLC).

Results: The ganciclovir solutions (0.5% and 1.0%) maintained therapeutic ganciclovir levels in the corneal endothelium above the effective dose required for 50% inhibition (ED50) up to 6 h, albeit with a swift decline thereafter. The 0.15% ganciclovir gel maintained higher therapeutic concentrations in the corneal endothelium for up to 12 h, exceeding the ED50. Serum concentrations of ganciclovir were significantly elevated in the groups receiving combined systemic administration.

Conclusion: Topical application of 0.15% ganciclovir gel maintained high endothelial concentrations, well above the therapeutic threshold, with or without systemic administration. Furthermore, the observed increase in ganciclovir levels within the plasma and aqueous humor following systemic administration posits it as a viable strategy for severe cases of cytomegalovirus corneal endotheliitis or those inadequately managed by local treatments alone.