Flagyl/Flagyl Forte Mechanism of Action

Trichomoniacide, anaerobicide.
Pharmacology: Pharmacodynamics: Flagyl Suspension: Metronidazole is an anti-infectious agent belonging 5-nitroimidazole group. Antibacterial spectrum of metronidazole concerns exclusively anaerobic pathogens. Susceptible species: more than 90% of the species are susceptible (S): Peptostreptococcus, C. perfringens, C. difficile, Bacteroides fragilis, Bacteroides sp., Fusobacterium, Clostridium sp., Prevotella, Veillonella.
Species with inconstant susceptibility: The susceptibility of the pathogens should be tested by an antibiogram: Bifidobacterium, Eubacterium.
Normally resistant species: More than 50 % of the species are resistant (R): Propionibacterium, Actinomyces, Mobilincus.
Antiparasitic activity: Trichomonas vaginalis, Giardia intestinalis, Entamoeba histolytica.
Flagyl Forte: Disposition of Metronidazole given orally or by intravenous injection remains constant, with average elimination time of 8 hours in healthy man. Metronidazole was detected in cerebrospinal fluid, saliva and breast milk in same concentration as in plasma. Metronidazole was also detected in the pus of hepatic abscess.
Pharmacokinetics: Absorption: Metronidazole is rapidly absorbed following oral administration, at least 80% in less than one hour.
The serum peak concentrations achieved following oral administration are similar to those obtained following intravenous administration of equivalent doses.
The oral bioavailability is 100% and not modified by ingestion of food.
Distribution: After a single dose administration of 500 mg metronidazole the average peak serum level is of 10 mg/ml one hour after the ingestion.
The plasma half-life is between 8 to 10 hours.
The protein binding is low: <20%.
The volume of distribution is high, on average of 40 L (i.e. 0.65 L/kg).
Diffusion is rapid and tissue concentrations are similar to the serum concentrations in: lungs, kidneys, liver, skin, bile, CSF, saliva, seminal fluid and vaginal secretions.
Metronidazole crosses the placenta barrier and is excreted in breast milk.
Metabolism: Metronidazole is metabolized by oxidation in the liver in two metabolites: The alcoholic metabolite which has a bactericidal activity on the anaerobic pathogens on average 30% in comparison with the metronidazole, and an elimination half-life of 11 hours.
The acid metabolite is low with a bactericidal activity of 5%.
Elimination: Hepatic and biliary concentrations are high. Colon and fecal concentrations are low.
Excretion is mainly urinary, metronidazole and its metabolites represent 35 to 65% of the ingested dose.