The effect of acetazolamide on the kinetics of four newer β-lactams in the aqueous humor

Abstract

Objective. To evaluate whether the effect of acetazolamide on piperacillin's aqueous humor concentrations observed in animals exists also in humans for ceftazidime, cefotaxime, ceftriaxone and aztreonam. Methods. One hundred and eighty-eight patients undergoing eye cataract surgery were randomly allocated to receive intravenous ceftazidime, cefotaxime, aztreonam or ceftriaxone with (subgroup A) or without (subgroup B) concomitant oral administration of acetazolamide. Antibiotic concentrations in serum and the aqueous humor, simultaneously sampled during the operation, were measured using an agar well diffusion technique, and the ratios of the concentrations of aqueous humor to serum were calculated and compared. Statistical analysis was performed by using the paired t-test. Results. Mean aqueous humor ceftazidime concentrations at 2, 4 and 6 h were 24.65, 16.4 and 8.6 mg/L (subgroup A), and 4.26, 8.66 and 5.61 mg/L (subgroup B). Corresponding concentrations of cefotaxime were 1.75, 1.0 and 0.77 mg/L (subgroup A), and 1.11, 0.81 and 0.58 mg/L (subgroup B), and of aztreonam 6.9, 5.84 and 3.61 mg/L (subgroup A), and 3.38, 2.57 and 1.48 mg/L (subgroup B). Ceftriaxone concentrations at 2, 4, 6 and 12 h were 1.78, 1.49, 1.57 and 1.41 mg/L (subgroup A), and 1.35, 0.95, 1.08 and 0.85 mg/L (subgroup B). The differences in aqueous humor concentrations when acetazolamide was administered were statistically significant (P < 0.05), with the exception of ceftazidime 6 h, cefotaxime 6 h and ceftriaxone 2 h. Conclusions. Although acetazolamide resulted in statistically significant increases in the aqueous humor concentrations of all the antibiotics tested, this effect was most marked for ceftazidime.