Amherst Lab


Full Prescribing Info
Pharmacologic Classification: Antibacterial/Antiprotozoal.
Pharmacology: Pharmacokinetics: Bioavailability: At least 80% of metronidazole is absorbed from the gastrointestinal tract after oral administration. Peak plasma concentrations of approximately 5 and 10 mcg/mL are achieved, usually within 1 to 2 hours, after single doses of 250 mg and 500 mg, respectively.
Less than 20% of the circulating metronidazole is bound to plasma proteins. Metronidazole is widely distributed into most body tissues and fluids including bone, bile, saliva, pleural and peritoneal fluids, vaginal and seminal fluids, and the CSF after IV administration. Distribution is similar whether the drug is administered orally or by IV infusion. CSF concentrations of metronidazole are approximately 43% of plasma concentrations in patients with inflamed meningitis. The drug also distributes into erythrocytes. It crosses the placenta and enters breast milk. Some accumulation and consequently higher concentrations occur when multiple doses are given. The rate of absorption and peak plasma concentrations of metronidazole is decreased when administered with food; however, the total amount of drug absorbed is not affected.
Adults with normal renal and hepatic functions have been reported to have an average plasma half-life of 6-8 hours. A significant amount of metronidazole (30-60%) is metabolized in the liver by hydroxylation, oxidation and glucuronide conjugation. The major metabolite is 2-hydroxymethyl metronidazole, which has some antibacterial and antiprotozoal activity.
Approximately 20% of metronidazole is excreted in urine and 3% in feces within 24 hours. After 5 days, the amount excreted in the urine increases to 77% and that excreted in feces to 14%. Fecal excretion accounts for 6% to 15% of the given dose. Both unchanged drug and metabolites are excreted in the urine and the feces. The mean elimination half-life of metronidazole is roughly 8 hours. Decreased renal function does not appear to alter the single dose pharmacokinetics of metronidazole although the elimination half-life of the metabolites is prolonged. Geriatric patients may have decreased urinary excretion of metronidazole. The drug is removed by hemodialysis but not by peritoneal dialysis. It can color the urine reddish-brown due to water-soluble pigments formed during metabolism.
Infusion: Intravenous administration of a loading dose of 15 mg/kg followed by 7.5 mg/kg metronidazole every 6 hours in healthy adults produces peak plasma concentrations of 26 µg/mL and troughs of 18 mcg/mL at steady-state.
Treatment of infections caused by susceptible anaerobic microorganisms.
Perioperative prophylaxis to reduce the incidence of post-operative bacterial infections in patients at high risk for such infections.
Treatment of intestinal and extraintestinal or invasive amoebiasis including amoebic liver abscess.
Treatment of pelvic inflammatory disease (PID) in combination with fluoroquinolones.
Dosage/Direction for Use
Tablet: See Table 1.

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Infusion: See Table 2.

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Special Precautions
Use with caution in patients with severe hepatic disease since these patients metabolize metronidazole slowly, with resultant accumulation of metronidazole and its metabolites in the plasma.
Alcoholic beverages should be avoided during metronidazole therapy and for at least 3 days afterward.
Patients with history of blood dyscrasias should use metronidazole with caution. Total and differential leukocyte counts should be performed before and after treatment especially when repeated courses of the drug are necessary.
Patients receiving corticosteroids and patients predisposed to edema should use metronidazole with caution.
Candida overgrowth in the gastrointestinal or genital tract may occur during metronidazole therapy and may require treatment with an agent with activity against Candida.
Adverse Reactions
Nervous System Effects: Serious adverse reactions include convulsive seizures and peripheral neuropathy. The latter is characterized mainly by numbness or paresthesia of an extremity. Dizziness, vertigo, incoordination, ataxia, confusion, irritability, depression, weakness, headache, tinnitus, hearing loss, and insomnia have also been reported with the use of metronidazole. Other effects include nervousness, malaise or syncope.
Gastrointestinal Effects: Nausea, accompanied by headache, anorexia, dry mouth and sharp, unpleasant metallic taste, vomiting, abdominal discomfort, and diarrhea have been reported with the use of metronidazole. Occasionally, epigastric distress and constipation; rarely, pseudomembranous colitis has also been reported.
Rare cases of acute pancreatitis, which generally abated on withdrawal of the drug, have been reported.
Hematologic Effects: Reversible neutropenia (leukopenia); rarely, reversible thrombocytopenia. Very rare cases of agranulocytosis were also reported. One patient experienced bone marrow aplasia with metronidazole therapy.
Cardiovascular Effects: Flattening of the T-wave may be seen in electrocardiographic tracings.
Sensitivity Reactions: Urticaria, pruritus, maculopapular rash, erythematous rash, flushing, nasal congestion, dryness of mouth (or vagina or vulva), fever, and fleeting joint pains sometimes resembling "serum sickness". Aseptic meningitis and photosensitivity reactions have occurred rarely.
Genitourinary Effects: Dysuria, cystitis, polyuria, incontinence, and a sense of pelvic pressure. Urethral burning or discomfort, dryness of the vagina, proliferation of Candida in the vagina, dyspareunia, decreased libido, proctitis, have also occurred. Genital pruritus, dysmenorrhea and urinary tract infection have also been reported.
Instances of darkened urine have also been reported. Although the pigment which is probably responsible for this phenomenon has not been identified, it is most certainly a metabolite of metronidazole and seems to have no clinical significance.
Respiratory Effects: Upper respiratory tract infections, rhinitis, sinusitis, and pharyngitis.
Others: Thrombophlebitis has been reported after IV infusion of metronidazole. Patients taking metronidazole and alcoholic beverages concomitantly may experience abdominal distress, nausea, vomiting, flushing, or headache. A modification of the taste of alcoholic beverages has also been reported.
MIMS Class
Antiamoebics / Other Antibiotics
ATC Classification
J01XD01 - metronidazole ; Belongs to the class of imidazole derivative antibacterials. Used in the systemic treatment of infections.
P01AB01 - metronidazole ; Belongs to the class of nitroimidazole derivatives antiprotozoals. Used in the treatment amoebiasis and other protozoal diseases.
Dazomet infusion 500 mg/100 mL
100 mL x 1's
Dazomet tab 500 mg
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