Metronidazole
General
- Type: Other antibiotics
- Dosage Forms:
- IV
- PO: 250mg; 375mg; 500mg
- Common Trade Names: Flagyl
Adult Dosing
General
- PO
- 500mg PO q6-8h x 7-10 days
- First Dose: 500mg PO x 1
- IV
- 15mg/kg IV x1, then 7.5mg/kg IV q6h
- First Dose: 15mg/kg IV x1
- Max: 1 gram/dose
Indications by Disease
| Disease | Dose | Context |
|---|---|---|
| Acute diarrhea | 750mg PO three times daily for 5-10 days | Entamoeba |
| Acute diarrhea | 250mg PO q8hrs for 7-10days | Giardia |
| Acute necrotizing ulcerative gingivitis | 500mg PO three times daily x 7 days | Uncomplicated |
| Acute tetanus | 500mg IV (7.5mg/kg) q6hrs | Active tetanus |
| Amebiasis | 750mg PO q8h x 5-10 days | Intestinal colitis |
| Ascending cholangitis | 500mg IV q8hrs | Combined with ciprofloxacin |
| Bacterial vaginosis | 500 mg PO Twice Daily for 7 days | First Line |
| Bacterial vaginosis | 500mg PO Twice a day x 7 days | Pregnant |
| Bacterial vaginosis | 500mg PO Twice a day x 7 days | Sexual Assault Prophylaxis |
| Brain abscess | 500mg IV q6hr | Otogenic |
| Clostridium difficile | 500mg PO or IV three times daily for 10 days | Non-Severe (third line) |
| Diabetic foot infection | 500mg IV q8hrs | Inpatient DFI |
| Diverticulitis | 500mg PO Q8hrs | Uncomplicated, Alternative |
| Diverticulitis | 500mg PO Q8h x 5 days | Uncomplicated, PCN allergy |
| Epidural abscess (spinal) | 500mg (7.5mg/kg) q6 hrs | Empiric |
| Giardia lamblia | 250mg PO q8h x 5-7 days; Alt: 2 g PO q 24h x 3 days | Giardiasis |
| Helicobacter pylori | 250-375mg PO q6h x 10-14 days (in combination) | H. pylori |
| Ludwig's angina | 500 mg IV q6 hrs | Immunocompetent |
| Ludwig's angina | 500 mg IV q6 hrs | Immunocompromised |
| Pelvic inflammatory disease | 500mg IV or PO q12hr | Inpatient |
| Pelvic inflammatory disease | 500mg PO BID x 14 days | Outpatient; recommended empirically by CDC and European guidelines |
| Peritonitis | 500mg IV q8hrs | Primary |
| Peritonitis | 500mg IV q8hrs | Allergy/Prior exposure |
| Peritonsillar abscess | 500mg QID | Outpatient |
| Peritonsillar abscess | 500mg IV three times daily | Inpatient |
| Postpartum endometritis | 500mg IV or PO q8hrs | >48hrs postpartum; combined with Doxycycline |
| Trichomonas vaginalis | 500mg PO BID for 7 days | Non-Pregnant |
| Trichomonas vaginalis | 500mg PO BID for 7 days | Pregnant |
| Urethritis in men | 2 g PO in a single dose | Recurrent/Persistent, Trichomonas |
Pediatric Dosing
(<1200g)
- 7.5 mg/kg PO/IV q48h
- First Dose: 7.5 mg/kg PO/IV x 1
(>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
(>1 Month Old)
- 30 mg/kg/day PO/IV q6h
- First Dose: 7.5 mg/kg PO/IV x 1
- Max: 4 g/day
Indications by Disease
| Disease | Dose | Context |
|---|---|---|
| Acute tetanus | 7.5mg/kg IV q6hrs (max 500mg/dose) x 7-10 days | Pediatric Active tetanus |
| Brain abscess | 7.5mg/kg IV q6hrs (max 500mg) | Pediatric Empiric |
| Clostridium difficile | 7.5mg/kg PO/IV TID x 10 days (max 500mg/dose) | Pediatric Non-Severe (third line) |
| Epidural abscess (spinal) | 7.5mg/kg IV q6hrs (max 500mg) | Pediatric Empiric |
| Infectious tenosynovitis | 7.5mg/kg IV four times daily | Pediatrics |
| Ludwig's angina | 7.5mg/kg IV q6hrs (max 500mg) | Pediatric Immunocompetent |
| Ludwig's angina | 7.5mg/kg IV q6hrs (max 500mg) | Pediatric Immunocompromised |
| Peritonitis | 7.5mg/kg IV q8hrs (max 500mg) | Pediatric |
| Peritonsillar abscess | 7.5mg/kg IV q8hrs (max 500mg/dose) | Pediatric Inpatient |
| Tetanus | Same as Standard Pediatric Age/Weight Dosing | Tetanus |
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
- Adult
- 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
- Disulfiram 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
- Disulfiram effect (should abstain from ETOH at least two days after last dose)
- 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
Antibiotic Sensitivities[1]
Key
- S susceptible/sensitive (usually)
- I intermediate (variably susceptible/resistant)
- R resistant (or not effective clinically)
- S+ synergistic with cell wall antibiotics
- U sensitive for UTI only (non systemic infection)
- X1 no data
- X2 active in vitro, but not used clinically
- X3 active in vitro, but not clinically effective for Group A strep pharyngitis or infections due to E. faecalis
- X4 active in vitro, but not clinically effective for strep pneumonia
See Also
References
- ↑ Sanford Guide to Antimicrobial Therapy 2014
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