INTRAVENOUS CEFAZOLIN IN PENETRATING EYE INJURIES .1. EFFECTS OF TRAUMA AND MULTIPLE DOSES ON INTRAOCULAR DELIVERY

The poor intraocular penetration of systemically administered antibiot ics has raised questions regarding their usefulness as prophylactic ag ents in the management of penetrating eye injuries. Cefazolin was admi nistered intravenously to rabbits with penetrating eye injuries to det ermine the influence of trauma on ocular pharmacokinetics. Following a standardized penetrating eye injury in 27 New Zealand white rabbits, animals were divided into three groups that received either three, six , or nine doses of intravenous cefazolin every 8 h. Cefazolin levels w ere then measured in the traumatized eye, the non-traumatized (control ) fellow eye, and in the serum of each animal. In the three treatment groups vitreous concentrations of cefazolin were significantly higher in traumatized eyes than in the non-injured eyes. After three doses, v itreous concentrations of cefazolin in traumatized eyes averaged 9.1 m g/l; mean concentrations of cefazolin in non-injured eyes were 0.6 mg/ l (P<0.0002). After six doses of intravenous cefazolin, vitreous conce ntrations in traumatized eyes averaged 7.3 mg/l; cefazolin levels in n on-injured eyes were 0.6 mg/l in the non-traumatized eyes (P<0.0005). After nine doses, vitreous cefazolin concentrations in traumatized eye s averaged 9.7 mg/l, while mean levels in the non-traumatized eyes wer e all 0.05 mg/l (P < 0.0002). This work suggests that penetrating inju ries of the eye alter ocular pharmacokinetics, resulting in high intra ocular concentrations of systemically administered cefazolin.