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Systemic antibiotic prophylaxis in penetrating ocular injuries. An experimental study
1Department of Ophthalmology, University of Southern California School of Medicine, Doheny Eye Institute, Los Angeles.
Abstract:
Intraocular concentrations of systemically administered gentamicin and cefazolin in eyes after a standard penetrating ocular injury were measured to determine the effect of eye injury on ocular pharmacokinetics. Twenty pigmented rabbits were divided into two groups. A standard, 8-mm wound was made at the pars plana of one eye in each animal. Group 1 consisted of 10 rabbits that were treated with cefazolin (75 mg/kg), and Group 2 consisted of 10 rabbits that were given gentamicin (2 mg/kg). Fellow eyes, which sustained no trauma, served as control eyes. All groups received intravenous injections every 8 hours for 72 hours, beginning immediately after repair of the wound. After 72 hours, samples were obtained from the anterior chamber, vitreous cavity, and serum. Standardized bioassays for detection of gentamicin or cefazolin were performed. Significant concentrations of intravitreal cefazolin (9.6 micrograms/ml) and gentamicin (0.60 micrograms/ml) were found in the traumatized eyes in comparison to control eyes (P = 0.0001; P = 0.006). Cefazolin exhibited excellent penetration, achieving concentrations well above minimum inhibitory concentration values for most organisms. Gentamicin levels, however, were well below acceptable therapeutic levels. This study suggests that systemically administered cefazolin can achieve significant intravitreal penetration at minimum inhibitory concentrations after penetrating injury.
Insights
Systemic cefazolin achieved therapeutic intravitreal concentrations after penetrating eye injury, unlike gentamicin. This indicates cefazolin
Area of Science:
- Ophthalmology
- Pharmacokinetics
- Infectious Diseases
Background:
- Penetrating ocular injuries can compromise intraocular drug delivery.
- Systemic antibiotics are often used to treat or prevent infection following eye trauma.
Purpose of the Study:
- To evaluate the intraocular penetration and pharmacokinetic profile of systemically administered cefazolin and gentamicin after penetrating ocular injury in rabbits.
- To determine if eye injury affects ocular drug concentrations.
Main Methods:
- Twenty rabbits underwent a standard 8-mm penetrating ocular injury.
- Group 1 received intravenous cefazolin (75 mg/kg); Group 2 received intravenous gentamicin (2 mg/kg) every 8 hours for 72 hours.
- Intraocular (anterior chamber, vitreous) and serum concentrations were measured via bioassay.
Main Results:
- Traumatized eyes showed significantly higher cefazolin (9.6 µg/mL) and gentamicin (0.60 µg/mL) concentrations compared to control eyes (P < 0.001).
- Cefazolin achieved concentrations exceeding minimum inhibitory levels for many pathogens.
- Gentamicin levels remained below therapeutic targets.
Conclusions:
- Systemic cefazolin demonstrates effective intravitreal penetration post-penetrating ocular injury.
- Systemic gentamicin shows poor intraocular penetration in this model.
- Cefazolin may be a suitable systemic option for managing ocular infections after penetrating trauma.