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Ocular penetration of topically applied gentamicin
Abstract:
The biologically available concentration of gentamicine sulfate in eight ocular tissues of 140 rabbits and 96 humans was measured by a modified disc diffusion technique. If enough topically administered gentamicine was applied, this bioassay detected it in all ocular tissues tested except the lens nucleus. The decay of antibiotic activity was faster in some tissues, eg, aqueous, than in others. A higher level of antibiotic was found in corneas altered by sutures than in virgin tissue. The degree of inflammation, the frequency of application, and the interval between the drops are directly proportional to the antibiotic level in the tissues. The antibiotic free vehicle of commercial 0.3 per cent gentamicin drops possesses an antibacterial potential.
Insights
Topical gentamicin sulfate reaches most ocular tissues, except the lens nucleus. Antibiotic levels depend on inflammation, application frequency, and vehicle properties, influencing gentamicin
Area of Science:
- Ophthalmology
- Pharmacology
- Microbiology
Background:
- Gentamicin sulfate is a widely used antibiotic for ocular infections.
- Understanding its penetration and persistence in ocular tissues is crucial for effective treatment.
Purpose of the Study:
- To quantify the biologically available concentration of gentamicin sulfate in various ocular tissues.
- To investigate factors influencing gentamicin sulfate levels in ocular tissues.
Main Methods:
- A modified disc diffusion bioassay was employed.
- Measurements were taken in eight ocular tissues from rabbits and humans.
Main Results:
- Gentamicin sulfate was detected in all tested ocular tissues except the lens nucleus.
- Antibiotic activity decayed faster in some tissues (e.g., aqueous humor).
- Altered corneas (sutured) showed higher antibiotic levels than virgin tissue.
- Inflammation, application frequency, and interval between drops correlated with tissue antibiotic levels.
- The vehicle of commercial gentamicin drops exhibited antibacterial potential.
Conclusions:
- Topical gentamicin sulfate effectively penetrates most ocular tissues.
- Tissue-specific factors and application parameters significantly influence gentamicin sulfate bioavailability.
- The non-antibiotic components of gentamicin formulations may contribute to antibacterial effects.