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Metronidazole / Flagyl

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Tablets: 250 mg & 500 mg




Tablets: 200 mg & 400 mg
Suspension: 200mg/5mL in 30 mL or 60 mL bottles


Metronidazole is both a powerful bactericidal agent with activity against most anaerobic bacteria (bacteria that does not require the presence of oxygen to grow), and an amebicide with effective activity against Entamoeba histolytica, Trichomonas, Giardia and Balantidium coli.

It is rapidly absorbed and widely distributed from the gastrointestinal tract.

The drug is found in most body tissues, including bone, abscesses, CNS, as well as crossing the placental barrier. It is metabolized in the liver and excreted in milk, feces, and urine, coloring the urine dark brown.


Used in bone infections, infections of the tooth socket and abscesses where anaerobic bacteria are likely to be present, and in other enteric and systemic anaerobic infections.

Drug Interactions or Contraindications

Contraindicated in rats where neurological disorders are present.

Not recommended for nursing or pregnant animals.

Avoid concurrent use with phenobarbital, and cimetidine.

It is compatible with all but the following drugs:
cefamandole naftate
dopamine hcl

Adverse Reactions

CNS:  lethargy, weakness, poor coordination

Blood:  transient neutopenia, leukopenia

Endocrine: hypoglycemia, hypocalcemia

GI:  anorexia, diarrhea, stomatitis

GU: darkened or red-brown urine, cystitis, polyuria, dysuria

Skin:  pruritus (itching)

Other:  hepatotoxicity

Dosage Recommendations

10 mg/kg to 40 mg/rat, PO, q24hrs  1  2


10 mg/kg to 40 mg/kg, PO, q24hrs  34


10 mg/kg to 50 mg/kg, q12hrs   11


  • Tablets and powder for injection should be stored at less than 30 degrees and protected from light.
  • Give with food to avoid GI distress.
  • In treating suspected polymicrobial infections, where a broader coverage may be needed, synergistic or combination drugs may be used. The following drugs may be seen used simultaneously with metronidazole: aminoglycosides (e.g., amikacin or gentamicin), fluoroquinolones (e.g., enrofloxacin or orbifloxicin), chloramphenicol.  1

Posted on June 23, 2003, 15:46, Last updated on August 24, 2014, 21:05 | Anti-Infectives

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