Cefmetazole

General

• Type: 2nd generation Cephalosporin
• Group: Cephamycin
• Dosage Forms: Powder for injection
• Dosage Strengths: 1g, 2g
• Routes of Administration: IV
• Common Trade Names: Zefazone

Adult Dosing

General

• Mild-Moderate: 2g IV q6-12h
• Severe: 2g IV q6h
• Max: 8g/day

Surgical Prophylaxis

• 1-2g IV 30-90 min pre-op
• May repeat at 8 and 16 hours post-op

Uncomplicated Gonorrhea

• 1g IM x1 with 1g oral Probenecid

Pediatric Dosing

General

• Safety and effectiveness in pediatric patients have not been established.

Special Populations

• Pregnancy: B
• Lactation: Excreted in trace amounts; use with caution
• Renal
  • Adult
    • CrCl 50-90: 1-2g q12h
    • CrCl 30-49: 1-2g q16h
    • CrCl 10-29: 1-2g q24h
    • CrCl <10: 1-2g q48h
    • Hemodialysis: Administer dose after dialysis
  • Pediatric
    • Not defined
• Hepatic
  • No adjustment defined

Contraindications

• Allergy to class/drug
• History of cephalosporin-associated hemolytic anemia

Adverse Reactions

Serious

• Anaphylaxis
• Stevens-Johnson Syndrome
• Clostridium difficile
• Hypoprothrombinemia (due to N-MTT side chain)
• Disulfiram-like reaction (with alcohol ingestion, due to N-MTT side chain)
• Hemolytic Anemia

Common

• Diarrhea
• Rash
• Nausea and Vomiting
• Injection site pain/phlebitis
• Elevated LFTs

Pharmacology

• Half-life: 1.2h (prolonged in renal failure)
• Metabolism: Minimally metabolized (15% is metabolized to open beta-lactam ring)
• Excretion: Urine (85% unchanged)
• Mechanism of Action: Bactericidal; inhibits cell wall mucopeptide synthesis. As a cephamycin, it is more resistant to beta-lactamases (especially from anaerobes) than 1st generation cephalosporins.

Antibiotic Sensitivities

Group	Organism	Sensitivity
Gram Positive	Strep. Group A, B, C, G	S
	Strep. Pneumoniae	S
	Viridans strep	S
	Strep. anginosus gp	X1
	Enterococcus faecalis	R
	Enterococcus faecium	R
	MSSA	S
	MRSA	R
	CA-MRSA	R
	Staph. Epidermidis	I
	C. jeikeium	R
	L. monocytogenes	R
Gram Negatives	N. gonorrhoeae	S
	N. meningitidis	S
	Moraxella catarrhalis	S
	H. influenzae	S
	E. coli	S
	Klebsiella sp	S
	E. coli/Klebsiella ESBL+	I
	E coli/Klebsiella KPC+	R
	Enterobacter sp, AmpC neg	R
	Enterobacter sp, AmpC pos	R
	Serratia sp	R
	Serratia marcescens	R
	Salmonella sp	X1
	Shigella sp	X1
	Proteus mirabilis	S
	Proteus vulgaris	S
	Providencia sp.	R
	Morganella sp.	R
	Citrobacter freundii	R
	Citrobacter diversus	I
	Citrobacter sp.	I
	Aeromonas sp	X1
	Acinetobacter sp.	R
	Pseudomonas aeruginosa	R
	Burkholderia cepacia	R
	Stenotrophomonas maltophilia	R
	Yersinia enterocolitica	X1
	Francisella tularensis	X1
	Brucella sp.	X1
	Legionella sp.	R
	Pasteurella multocida	X1
	Haemophilus ducreyi	X1
	Vibrio vulnificus	X1
Misc	Chlamydophila sp	R
	Mycoplasm pneumoniae	R
	Rickettsia sp	R
	Mycobacterium avium	R
Anaerobes	Actinomyces	S
	Bacteroides fragilis	S
	Prevotella melaninogenica	S
	Clostridium difficile	R
	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

• Antibiotics (Main)