Ocular penetration of topically applied norfloxacin 0.3% in the rabbits and in humans
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A M Bron1, A Péchinot, C Garcher
1Ophthalmology Department, University of Burgundy, Dijon, France.
Abstract:
The kinetics of topically applied norfloxacin 0.3 percent were studied in rabbit and man. All measurements were performed by high-pressure liquid chromatography. Norfloxacin concentrations were investigated five to 120 minutes in rabbit ocular tissues after instillation of a single drop. In normal eyes, after 30 minutes, mean +/- SEM levels were 14.3 +/- 3.7 micrograms/g in cornea, 3.3 +/- 0.7 micrograms/g in conjunctiva, 0.2 +/- 0.1 microgram/g in aqueous humor. After removal of the corneal epithelium concentrations were as follows: 84.2 +/- 15.8 micrograms/g, 7.3 +/- 2.3 micrograms/g, 8.6 +/- 1.9 micrograms/g respectively. Penetration in posterior ocular tissues were rather poor. In human eyes, the intracorneal concentrations were assessed in patients being operated on corneal grafts. After instillation of 5 drops, the concentration in cornea was 15.5 +/- 2.1 micrograms/g. These data show that therapeutic levels of norfloxacin can be achieved in anterior ocular tissues, which may be of help in superficial infections of the eye.
Insights
Topical norfloxacin achieved therapeutic levels in rabbit and human anterior ocular tissues, aiding superficial eye infections. Concentrations were highest in the cornea, especially after epithelial removal.
Area of Science:
- Ophthalmology
- Pharmacokinetics
- Microbiology
Background:
- Topical antibiotics are crucial for treating ocular infections.
- Understanding drug penetration into ocular tissues is vital for effective treatment.
Purpose of the Study:
- To investigate the ocular tissue kinetics of topically applied norfloxacin (0.3%).
- To determine norfloxacin concentrations in various ocular tissues in rabbits and humans.
Main Methods:
- High-performance liquid chromatography (HPLC) was used for all measurements.
- Norfloxacin concentrations were measured in rabbit ocular tissues (cornea, conjunctiva, aqueous humor) at various time points (5-120 minutes).
- Intracorneal concentrations were assessed in human subjects undergoing corneal graft surgery.
Main Results:
- In normal rabbit eyes, peak concentrations at 30 minutes were 14.3 µg/g in the cornea, 3.3 µg/g in the conjunctiva, and 0.2 µg/g in the aqueous humor.
- Corneal epithelium removal significantly increased norfloxacin levels in the cornea (84.2 µg/g), conjunctiva (7.3 µg/g), and aqueous humor (8.6 µg/g).
- Human corneal concentrations reached 15.5 µg/g after 5 drops, indicating good penetration.
Conclusions:
- Topical norfloxacin effectively penetrates anterior ocular tissues, achieving therapeutic concentrations.
- These findings support the use of norfloxacin for superficial ocular infections.
- Further research could explore optimal dosing for specific ocular conditions.