[Study on transfer of aztreonam into female genital organs]

Aztreonam (AZT) is a newly developed beta-lactam antibiotic for use of intravenous injection. It is the first drug in the world of monobactam series with the structural characteristic of monocyclic beta-lactam. The antimicrobial spectrum of AZT is unique, having little or no susceptibility against Gram-positive organisms and anaerobes, but showing high susceptibility against aerobic Gram-negative rods including Pseudomonas. One gram of AZT was given intravenously to 32 patients prior to abdominal total hysterectomy for uterine myoma. Bilateral uterine arteries were clamped at 0.25, 0.5, 1, 2, 4, 8 or 12 hours after administration, and serum samples and uterine tissues were taken for the measurement of AZT concentration by bioassay method. Little difference was found in the serum concentration between cubital venous and uterine arterial serum, the half-lives of both being 2.11 hours. The initial concentrations were estimated to be 68.0 micrograms/ml and 63.9 micrograms/ml, respectively. While the peak concentrations of the portio vaginalis, cervix uteri, myometrium and oviduct were obtained at about 10 minutes, those of the endometrium and ovary were at 18.2 minutes and 31.3 minutes, respectively. They were as follows; the portio vaginalis 50.0 micrograms/g, the cervix uteri 43.6 micrograms/g, the myometrium 29.8 micrograms/g, the oviduct 44.7 micrograms/g, the endometrium 27.3 micrograms/g, the ovary 29.0 micrograms/g. After showing peak, tissue levels were kept fairly high up to 3 hours, then decreased gradually as time passed up to approximately 8 hours. Judging from its favorable transfer into the uterine tissues and MICs against main clinical isolates in the field of obstetrics and gynecology, AZT is evaluated to be clinically useful in the treatment of obstetrical and gynecological infections.