Metronidazole

General

• Type: Other Antibacterials
• Dosage Forms:
  • IV
  • PO: 250mg; 375mg; 500mg
• Common Trade Names: Flagyl

Adult Dosing

General

• PO
  • 500 mg PO q6-8h x 7-10 days
  • First Dose: 500 mg PO x 1
• IV
  • 15mg/kg IV x1, then 7.5mg/kg IV q6h
  • First Dose: 15mg/kg IV x1
• Max: 1 gram/dose

Amebic Liver Abscess

• 500-750 mg PO q8h x 5-10 days

Colorectal Surgery Infection Prophylaxis

• 15 mg/kg IV x 1
• Complete infusion 1h prior to surgery, then 7.5 mg/kg IV q6h x 2
• Max: 1 g/dose

Intestinal Amebiasis

• 750mg PO q8h x 5-10 days

PID

• 500mg PO q12 x 14 days
• See PID for full regimen

Bacterial Vaginosis

• Treatment
  • 500mg PO q12 x 7 days
  • Alt: May use 250mg PO q8h x 7 days in pregnant patients
• Prophylaxis (Sexual Assault)
  • 2 g PO x 1

Trichomoniasis

• Treatment
  • Immunocompetent: 2 g PO x 1
  • Immunocompromised: 500mg PO q12h x 7 days
• Prophylaxis (Sexual Assault)
  • 2 g PO x 1

=Giardiasis

• 250mg PO q8h x 5-7 days
• Alt: 2 g PO q 24h x 3 days

C. Difficile

• Mild-mod
  • 500mg PO q8h x 10-14 days
• Severe
  • 500mg IV q8h (give with vancomycin PO)

H. pylori

• 250-375mg PO q6h x 10-14 days (in combination)

Urethritis, recurrent/persistent (Non-Gonococcal)

• 2 g PO x 1 (with azithromycin)

Pediatric Dosing

General (<1200g)

• 7.5 mg/kg PO/IV q48h
• First Dose: 7.5 mg/kg PO/IV x 1

General (>1200g AND <1 Month Old)

• <7 days old
  • 7.5-15 mg/kg/day PO/IV q12-24h
  • First Dose: 7.5-15 mg/kg PO/IV x 1
• >7 days old
  • 15-30 mg/kg/day PO/IV q12h
  • First Dose: 7.5-15 mg/kg PO/IV x 1

General (>1 Month Old)

• 30 mg/kg/day PO/IV q6h
• First Dose: 7.5 mg/kg PO/IV x 1
• Max: 4 g/day

Special Populations

• Pregnancy: B
• Lactation: Safety conditional
• Renal Dosing
  • Adult
    • No adjustment for renal insufficiency
    • Hemodialysis: Give dose after dialysis
    • Peritoneal Dialysis: No supplement
  • Pediatric
    • CrCl <10: Decrease dose 50%
    • Hemodialysis: Give dose after dialysis
    • Peritoneal Dialysis: No supplement
• Hepatic Dosing (Adult & Pediatric)
  • Severe impairment: decrease dose, amount not defined

Contraindications

• Black Box: carcinogenic in mice and rats; avoid unnecessary use; reserved for approved conditions
• Allergy to class/drug
• Pregnancy (single 2 dose retimen)
• Alcohol use within 3 days
• Disulfram use within 14 days

Adverse Reactions

Serious

• Seizures
• Aseptic meningitis
• Perifpheral neuropathy
• Optic neuropathy
• Encephalopathy
• Hypersensitivity Reaction
• Stevens-Johnson Syndrome
• Toxic Epidermal Necrolysis
• Leukopenia
• Carcinogenicity (in animals)

Common

• Nausea and Vomiting
• Epigastric discomfort
• Diarrhea
• Metallic taste
• Rash
• Headache
• Dizziness
• Dark reddish-brown urine
• Candidiasis
• Thrombophlebitis (IV use)

Pharmacology

• Half-life: 8h
• Metabolism: Liver; CYP450: 2C9 inhibitor
• Excretion: Urine (70%); feces (15%)
• Mechanism of Action: Bactericidal

See Also

• Antibiotics (Main)

Source

• Epocrates