Intravenous cefazolin in penetrating eye injuries. A swine model

A swine model of penetrating ocular trauma was used to determine the delivery of systemically administered cefazolin to the vitreous cavity of traumatized and nontraumatized eyes. Thirty-one pigs received a scleral laceration to the right eye under anesthesia and then were given intravenous cefazolin every 8 hours. Seven pigs received nine doses at 17 mg/kg. Seven animals received three doses of 36 mg/kg, and six others received nine doses of this regimen. Six pigs received three doses of 79 mg/kg and five others received three doses of 190 mg/kg. Vitreous levels of cefazolin averaged 15.6 micrograms/mL in traumatized eyes but were less than 1 microgram/mL in control eyes of animals receiving three doses at 190 mg/kg (P < or = 0.025). Mean serum concentration in these animals was 49.3 micrograms/mL. Vitreous levels were less than 1 microgram/mL in traumatized and control eyes in animals given lower doses of cefazolin (range, 17-79 mg/kg) despite multiple treatments over 2 and 3 days. These data demonstrate that systemically delivered cefazolin achieves levels ten times the minimum inhibitory concentration for Staphylococcus epidermidis in injured eyes. Therapeutic intraocular levels can be obtained through intravenous dosing, provided that therapeutic serum concentrations are achieved.