Imipenem/Cilastatin

General

  • Type: Carbapenems
  • Dosage Forms:
  • Common Trade Names: Primaxin

Adult Dosing

General

  • Fully-susceptible organisms: 500mg IV q6 hours
  • Moderately-susceptible organisms: 1g IV q6-8 hours
  • Max: Lower of 50mg/kg or 4 g/day

UTI

  • 500mg IV q6h

Pneumonia, hospital acquired

  • 500mg IV q6h x7 days

Anthrax, systemic

  • 1g IV q6h for at least 2wk

Pediatric Dosing

General[1]

  • 60-100mg/kg/day IV divided q6 hours
  • First Dose: 10-16.6mg/kg IV x 1
  • Max: 4000mg/day

Anthrax, systemic

  • Neonates >32 wk gestation
    • 40-75 mg/kg/day IV divided q8-12h for at least 2wk
  • 1 month and older
    • 100 mg/kg/day IV divided q6h for at least 2wk

Special Populations

  • Pregnancy: C
  • Lactation: Use caution
  • Renal Dosing
    • Adult
      • If usual dose 500mg q6h
        • CrCl 60-89: 400mg q6h
        • CrCl 30-59: 300mg q6h
        • CrCl 15-29: 200mg q6h
        • CrCl <15: Avoid unless HD w/in 48h
        • HD: 200mg q6h, give dose after dialysis, no supplement
        • PD: No supplement
      • If usual dose 1000mg q8h
        • CrCl 60-89: 500mg q6h
        • CrCl 30-59: 500mg q8h
        • CrCl 15-29: 500mg q12h
        • CrCl <15: Avoid unless HD w/in 48h
        • HD: 500mg q12h, give dose after dialysis, no supplement
        • PD: No supplement
      • If usual dose 1000mg q6h
        • CrCl 60-89: 750mg q8h
        • CrCl 30-59: 500mg q6h
        • CrCl 15-29: 500mg q12h
        • CrCl <15: Avoid unless HD w/in 48h
        • HD: 500mg q12h, give dose after dialysis, no supplement
        • PD: No supplement
    • Pediatric
      • < 30 kg: Avoid use in renal impairment
      • > 30 kg:
        • CrCl 41-70: Decrease dose 50%
        • CrCl 21-40: Decrease dose 63%; give q8h
        • CrCl 6-20: Decrease dose 75%, give q12h
        • CrCl <5: Avoid unless HD w/in 48h
        • HD: Give dose after dialysis, no supplement
        • PD: No supplement
  • Hepatic Dosing
    • Adult: Not defined
    • Pediatric: Not defined

Contraindications

  • Allergy to class/drug

Adverse Reactions

Serious

Common

Pharmacology

  • Half-life: 1h
  • Metabolism:
    • Imipenem: Kidney
    • Cilastatin: Unknown
  • Excretion: Urine 70%
  • Mechanism of Action:
    • Bactericidal
    • Imipenem inhibits cell wall synthesis
    • Cilastatin inhibits renal dihydropeptidase I, preventing imipenem metabolism

Antibiotic Sensitivities[2]

Group Organism Sensitivity
Gram Positive Strep. Group A, B, C, G S
Strep. Pneumoniae S
Viridans strep S
Strep. anginosus gp S
Enterococcus faecalis S
Enterococcus faecium I
MSSA S
MRSA R
CA-MRSA R
Staph. Epidermidis S
C. jeikeium R
L. monocytogenes S
Gram Negatives N. gonorrhoeae X2
N. meningitidis S
Moraxella catarrhalis S
H. influenzae S
E. coli S
Klebsiella sp S
E. coli/Klebsiella ESBL+ S
E coli/Klebsiella KPC+ R
Enterobacter sp, AmpC neg S
Enterobacter sp, AmpC pos S
Serratia sp S
Serratia marcescens X1
Salmonella sp S
Shigella sp S
Proteus mirabilis S
Proteus vulgaris S
Providencia sp. S
Morganella sp. S
Citrobacter freundii S
Citrobacter diversus S
Citrobacter sp. S
Aeromonas sp S
Acinetobacter sp. I
Pseudomonas aeruginosa S
Burkholderia cepacia R
Stenotrophomonas maltophilia R
Yersinia enterocolitica S
Francisella tularensis X1
Brucella sp. X1
Legionella sp. R
Pasteurella multocida S
Haemophilus ducreyi X1
Vibrio vulnificus X1
Misc Chlamydophila sp R
Mycoplasm pneumoniae R
Rickettsia sp X1
Mycobacterium avium X1
Anaerobes Actinomyces S
Bacteroides fragilis S
Prevotella melaninogenica S
Clostridium difficile X2
Clostridium (not difficile) S
Fusobacterium necrophorum S
Peptostreptococcus sp. S

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. Red Book, 2012
  2. Sanford Guide to Antimicrobial Therapy 2014

Authors:

Yos Yachivev