Tear concentrations of topically applied ciprofloxacin

Area of Science:

• Ophthalmology
• Pharmacokinetics
• Microbiology

Background:

• Bacterial eye infections necessitate effective antimicrobial agents.
• Ciprofloxacin is a broad-spectrum fluoroquinolone antibiotic used in ophthalmic preparations.
• Understanding drug concentration in tears is crucial for therapeutic efficacy.

Purpose of the Study:

• To quantify tear concentrations of ciprofloxacin following topical ocular administration.
• To assess the duration of effective ciprofloxacin concentrations in the tear film.
• To compare achieved tear concentrations with minimum inhibitory concentrations (MICs) of common ocular pathogens.

Main Methods:

• An open-label study involving 20 healthy volunteers.
• Topical ocular application of ciprofloxacin 0.3% ophthalmic solution (Ciloxan).
• Tear sample collection using Schirmer tear strips at specified time points (30 min, 2, 3, 4 h).
• Quantification of ciprofloxacin concentrations via reverse-phase high-performance liquid chromatography (HPLC).

Main Results:

• Mean tear concentration of ciprofloxacin at 4 hours post-dosing was 16.0 µg/mL (95% CI: 8.15–23.79).
• Achieved concentrations remained significantly above the reported MICs (< or = 2 µg/mL) for 90% of common bacterial strains.
• Demonstrated sustained therapeutic levels in tear fluid up to 4 hours after a single dose.

Conclusions:

• Topical ciprofloxacin ophthalmic solution 0.3% achieves substantial and sustained concentrations in human tears.
• These concentrations are clinically relevant, exceeding the MICs required to inhibit a majority of common ocular pathogens.
• Supports the use of ciprofloxacin ophthalmic solution for effective treatment of bacterial conjunctivitis and other ocular infections.