Medgyl IV Mechanism of Action

Pharmacology: Metronidazole is active against a variety of anaerobic bacteria particularly Bacteroides fragilis. Its mechanism of action is reflected in a selective toxicity to anaerobic or microaerophilic micro-organisms and other, anoxic or hypoxic cells. In susceptible cells, the nitro group of metronidazole is reduced by electrotransport proteins with low redox potentials (such as ferrodoxin in clostridia); these proteins play a much more important role in the metabolism of such cells than they do in aerobes. Metronidazole thus acts as an electron ink and deprives the cell of required reducing equivalents.
Pharmacokinetics: Disposition of metronidazole in the body is similar for both oral and intravenous dosage forms, with an average elimination half-life in healthy humans of eight hours.
The major route of elimination of metronidazole and its metabolites is via the urine (60% to 80% of the dose), with fecal excretion accounting for 6 to 15% of the dose. The metabolites that appear in the urine result primarily from side-chain oxidation (1-(beta-hydroxyethyl)-2-hydroxymethyl-5-nitroimidazole and 2-methyl-5-nitroimidazole-1-yl-acetic acid) and glucuronide conjugation, with unchanged metronidazole accounting for approximately 20% of the total. Renal clearance of metronidazole is approximately 10 mL/min/1.73 m².
Metronidazole is the major component appearing in the plasma, with lesser quantities of the 2-hydroxymethyl metabolite also being present. Less than 20% of the circulating metronidazole is bound to plasma proteins. Both the parent compound and the metabolite possess in vitro bactericidal activity against most strains of anaerobic bacteria and in vitro trichomonacidal activity.
Metronidazole appears in cerebrospinal fluid, saliva, and breast milk in concentrations similar to those found in plasma. Bactericidal concentrations of metronidazole have also been detected in pus from hepatic abscesses.
Decreased renal function dose not alters the single-dose pharmacokinetics of metronidazole is decreased in patients with decreased liver function.