Metronidazole

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General

  • Type: Other Antibacterials
  • 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

Amebic liver abscess

  • 500-750mg PO q8h x 5-10 days

Colorectal Surgery Infection Prophylaxis

  • 15mg/kg IV x 1
  • Complete infusion 1h prior to surgery, then 7.5mg/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

  • 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

H. pylori

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

Urethritis, recurrent/persistent (Non-Gonococcal)

  • 2 g PO x 1 (with azithromycin)

Tetanus

  • 500 mg IV every 6 hours

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

Bacterial Vaginosis

<45kg
  • 15 mg/kg/day PO divided q12h x 7 days
  • First Dose: 7 mg/kg PO x 1
  • Max: 1 g/day
>45kg
  • 500mg PO divided q8h x 7 days
  • First Dose: 500mg PO x 1
  • Max: 2 g/day

Prophylaxis (sexual Assault)

<45kg'

  • 15 mg/kg/day PO divided q8h x 7 days
  • First Dose: 7 mg/kg PO x 1

>45kg

  • 2 g PO x 1

Tetanus

Same as Standard Pediatric Age/Weight Dosing

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

Common

Pharmacology

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

Antibiotic Sensitivities[1]

Group Organism Sensitivity
Gram Positive Strep. Group A, B, C, G R
Strep. Pneumoniae R
Viridans strep X1
Strep. anginosus gp X1
Enterococcus faecalis R
Enterococcus faecium R
MSSA R
MRSA R
CA-MRSA R
Staph. Epidermidis R
C. jeikeium R
L. monocytogenes R
Gram Negatives N. gonorrhoeae R
N. meningitidis R
Moraxella catarrhalis R
H. influenzae R
E. coli R
Klebsiella sp R
E. coli/Klebsiella ESBL+ R
E coli/Klebsiella KPC+ R
Enterobacter sp, AmpC neg R
Enterobacter sp, AmpC pos R
Serratia sp X1
Serratia marcescens R
Salmonella sp R
Shigella sp R
Proteus mirabilis X1
Proteus vulgaris R
Providencia sp. X1
Morganella sp. X1
Citrobacter freundii X1
Citrobacter diversus X1
Citrobacter sp. X1
Aeromonas sp X1
Acinetobacter sp. R
Pseudomonas aeruginosa R
Burkholderia cepacia R
Stenotrophomonas maltophilia R
Yersinia enterocolitica R
Francisella tularensis R
Brucella sp. R
Legionella sp. R
Pasteurella multocida X1
Haemophilus ducreyi R
Vibrio vulnificus R
Misc Chlamydophila sp R
Mycoplasm pneumoniae R
Rickettsia sp R
Mycobacterium avium R
Anaerobes Actinomyces R
Bacteroides fragilis S
Prevotella melaninogenica S
Clostridium difficile S
Clostridium (not difficile) S+'
Fusobacterium necrophorum S
Peptostreptococcus sp. I

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

  1. Sanford Guide to Antimicrobial Therapy 2014