Oral bioavailability of the monobactam aztreonam (SQ 26,776) in healthy subjects.

To investigate the oral bioavailability of aztreonam (SQ 26,776), we administered single 500-mg doses of this monobactam as an oral solution, as two 250-mg capsules, and as a 3-min intravenous infusion to 15 healthy male subjects at 1-week intervals according to a three-way crossover study design. Serum and urine samples were assayed by microbiological methods. The absolute systemic bioavailability of each oral formulation, defined as the ratio of areas under the serum concentration-time curves after oral and intravenous administration, was less than 1%. Peak serum levels achieved with oral solution, capsule, and intravenous infusion were 0.15, 0.14, and 56.7 micrograms/ml, respectively, and cumulative urinary excretion was 0.7, 0.6, and 68% of the administered dose, respectively.