Metronidazole
Trade and Other Names
Flagyl; many brands
available
Drug Class
Antibacterial, antiparasitic,
antiprotozoal
Mechanism of Action and
Clinical Use
Disrupts DNA in organism via
reaction with intracellular metabolite. Action is specific for anaerobic
bacteria and protozoa. Resistance is rare. Active against some protozoa,
including Giardia organisms; however, other drugs such as fenbendazole have been
used for Giardia infection.
Adverse Effects
Most severe adverse effect
is dose-related CNS toxicity. High doses have caused lethargy, CNS depression,
ataxia, vomiting, and weakness. Metronidazole may be mutagenic.
Contraindications,
Precautions, and Drug Interactions
Fetal abnormalities have not
been demostrated in animals with recommended doses, but use with caution during
pregnancy.
Instructions for Use
Metronidazole is one of the
most commonly used drugs for anaerobic infections. It is effective for
giardiasis; other drugs used for Giardia infection include albendazole,
fenbendazole, and quinacrine. Maximum dose that should be administered is 50-65
mg/kg,q24h, in any species. Tablets have been broken or crushed for oral
administration to cats; however, cats find these unpalatable.
Small Animal Dosage
Information
Anaerobic Infection:
Dogs: 15 mg/kg,q12h, PO; or
12 mg/kg, q8h, PO.
Cats: 10-25 mg/kg, q24h, PO.
Giardia Infection:
Dogs: 12-15 mg/kg,q12h, PO,
x 8 days.
Cats: 17 mg/kg (1/3
tablet/cat), q24h, PO, x 8 days