Distribution: It has a high penetrating ability, reaching bactericidal concentrations in most tissues and body fluids, including lungs, kidneys, liver, skin, cerebrospinal fluid, brain, bile, saliva, amniotic fluid, abscess cavities, vaginal secretion, seminal fluid, breast milk, penetrates the blood-brain barrier (BBB) and the placental barrier.
Volume of distribution: adults - approximately 0,55 l / kg, newborns 0,54-0,81 l / kg. The maximum concentration of the drug in the blood (FROMmOh) is from 6 to 40 μg / ml, depending on the dose. The connection with plasma proteins is 10-20%.
With intravenous administration of 500 mg for 20 minutes FROMmOh in the blood serum after 1 hour - 35.2 μg / ml. The concentration of the drug in the blood after 4 hours was 33.9 μg / ml, after 8 hours - 25.7 μg / ml. Cmin with subsequent administration of 18 μg / ml. TFROMmOh - 30-60 minutes, the therapeutic concentration persists for 6-8 hours. With normal bile formation, the concentration of metronidazole in the bile after IV introduction can significantly exceed the concentration in the plasma.
Biotransformation: In the body, about 30-60% of metronidazole is metabolized by hydroxylation, oxidation and glucuronation. The main metabolite (2-oxymetronidazole) also has antiprotozoal and antimicrobial effects.
Excretion: The half-life (T1/2) with normal liver function - 8 hours (6 to 12 hours), with alcohol damage of the liver - 18 hours (from 10 to 29 hours), in newborns born at term of pregnancy - 28-30 weeks - about 75 hours, 32- 35 weeks - 35 hours, 36-40 weeks - 25 hours.
It is excreted by the kidneys 60-80% (20% unchanged), through the intestine - 6-15%.
With severe renal dysfunction (creatinine clearance less than 10 ml / min) in patients after repeated administration can be observed cumulation of metronidazole in the blood serum, and therefore the dose should be reduced in half.
Metronidazole and major metabolites are rapidly removed from the blood during hemodialysis (T1/2 is reduced to 2.6 hours). When peritoneal dialysis is withdrawn in small quantities.