Pharmacokinetics and Tolerance of a Single Twelve-Tablet Dose of Trimethoprim (960 mg)-Sulfamethoxazole (4,800 mg)

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Abstract
To evaluate the potential usefulness of a single large oral dose of trimethoprim-sulfamethoxazole (TMP-SMZ) for the treatment of uncomplicated genitourinary gonorrhea, the pharmacokinetics of a 12-tablet dose containing 960 mg of TMP and 4,800 mg of SMZ were studied in 15 male volunteers, and the tolerance of this regimen was compared to that of a placebo in a double-blind crossover study. Both TMP and SMZ were rapidly absorbed. Peak mean serum concentrations (± standard deviation) of TMP, total SMZ, and free SMZ were 9.2 ± 2.2, 259.4 ± 40.9, and 233.7 ± 33.6 μg/ml, respectively. Elimination half-lives were 16.7, 14.6, and 12.9 h, respectively. When results were compared to data from similar studies after smaller doses, peak mean serum concentrations were proportional to dose, but elimination half-lives were longer after larger doses. Urinary concentrations of TMP, total SMZ, and free SMZ were many-fold higher than serum concentrations. Percents recovery (± standard deviation) in urine were 60.6 ± 10.6, 80.2 ± 7.8, and 37.4 ± 6.5%, respectively, during the 48 h after administration. The incidence of severe headache and of objective transient oliguria was significantly higher after TMP-SMZ than after placebo. Although the observed serum concentrations of TMP and SMZ surpassed concentrations necessary to inhibit clinical isolates of Neisseria gonorrhoeae in vitro for longer than 24 h, the adverse reactions associated with a 12-tablet dose of TMP-SMZ would preclude the clinical usefulness of such a therapeutic regimen.