Concentrations of Metronidazole and Tinidazole in Abdominal Tissues after a Single Intravenous Infusion and Repetitive Oral Administration

Abstract

Concentrations of metronidazole and tinidazole in serum and abdominal tissues were determined after a single 500-mg intravenous infusion or after a 5-day oral dosage of 500 mg three times daily in groups of 10 patients each. In the patients who got the single infusions, the concentrations in tissues (except fat) reached almost the serum levels 10 min after the infusion. At 24 h, the tinidazole concentrations in serum averaged 3.2 μg/ml and those of metronidazole 1.3 μg/ml. In the patients who got the 5-day oral dosages, the steady-state levels of tinidazole in both serum and tissues were twice as high as those of metronidazole.

Concentrations of metronidazole and tinidazole in male genital tissues

“…Comparative studies of the tissue penetration of nitroimidazoles are scanty. These studies have, however, demonstrated that after the same dosage, the steady-state concentrations of tinidazole both in serum and in several tissues were remarkably high as compared with those of metronidazole (6,(8)(9)(10)(11). The same was the case in the present study concerning male genital tissues.…”

“…At steady state (6,11) and even after a single dose (6,10,11), the concentrations of nitroimidazoles in tissues have been at about the same level as in the corresponding serum samples. The same was the case in the present study in regard to most male genital tissues.…”

“…This difference is naturally caused by the long elimination half-life of tinidazole. As we have recommended previously (6,11), the dose interval of the tinidazole treatment could be prolonged to 12 h and the concentrations would still exceed those of metronidazole with equal dose. However, so far there are no clinical data supporting this proposal.…”

“…Metronidazole and tinidazole are known to penetrate well into various tissues after both enteral and parenteral administration (6,(8)(9)(10)(11). The elimination half-life of tinidazole is 12 to 15 h, and that of metronidazole is 7 to 9 h (8).…”

“…The elimination half-life of tinidazole is 12 to 15 h, and that of metronidazole is 7 to 9 h (8). Owing to this difference, the steady-state concentrations of tinidazole in serum and tissues have been much higher than those given by the same dose of metronidazole (6,(8)(9)(10)(11). The prostate and the testis are problematic organs in regard to the tissue penetration of most drugs.…”