Effect of intravitreal dexamethasone on vitreous vancomycin concentrations in patients with suspected postoperative bacterial endophthalmitis.
OBJECTIVE
To study intravitreal dexamethasone and vancomycin concentrations, when used together in patients with suspected postoperative bacterial endophthalmitis. Animal studies had suggested that dexamethasone might decrease the concentration of vancomycin.


METHODS
Prospective randomized clinical trial in a tertiary referral center.


METHODS
Twenty-nine consecutive patients with suspected postoperative bacterial endophthalmitis underwent a vitreous biopsy followed by intravitreal injection of antibiotics (0.2 mg vancomycin, 0.05 mg gentamicin) and 400 mug dexamethasone or placebo. After 3-4 days, the intravitreal injection of antibiotics and dexamethasone or placebo was repeated. In 18 patients, a second biopsy was taken for repeat culture and measurement of vancomycin and dexamethasone concentrations.


RESULTS
In 20/29 patients (69%) the first vitreous cultures were positive; the second culture was negative in all cases. Thirteen out of 29 patients received dexamethasone. Dexamethasone concentrations showed an average of 25 ng/ml 3 days after injection, with an estimated half-life of 5.5 h. Vancomycin concentrations in patients given dexamethasone tended to be higher compared with those in the placebo group (P=0.061).


CONCLUSIONS
Intravitreal dexamethasone does not lead to decreased vancomycin concentrations, when given simultaneously in the treatment of patients with suspected bacterial endophthalmitis.
Gan
Ivan M
IM
The Rotterdam Eye Hospital, PO Box 70030, 3000 LM, Rotterdam, The Netherlands.
Ugahary
Luana C
LC
van Dissel
Jaap T
JT
van Meurs
Jan C
JC
D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000493:pharmacokinetics*; D001682:Biological Availability; D003907:Dexamethasone / Q000494:pharmacology*; D009877:Endophthalmitis / Q000188:drug therapy / Q000378:metabolism* / Q000382:microbiology; D015818:Eye Infections, Bacterial / Q000188:drug therapy / Q000378:metabolism* / Q000382:microbiology; D005260:Female; D005938:Glucocorticoids / Q000494:pharmacology*; D006207:Half-Life; D006801:Humans; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications; D011446:Prospective Studies; D014640:Vancomycin / Q000493:pharmacokinetics*; D014822:Vitreous Body / Q000378:metabolism* / Q000382:microbiology
D000900:Anti-Bacterial Agents; D005938:Glucocorticoids; D014640:Vancomycin; D003907:Dexamethasone