Cephamycin

General

• Type: 2nd generation Cephalosporin
• Dosage Forms: powder for injection
• Dosage Strengths: 1g, 2g, 10g
• Routes of Administration: IV, IM
• Common Trade Names: Mefoxin (Cefoxitin), Cefotan (Cefotetan)

Adult Dosing

General

• Cefoxitin: 1-2g IM/IV q6-8h
• Cefotetan: 1-2g IM/IV q12h
• Max: 12g/day (Cefoxitin); 6g/day (Cefotetan)

Pelvic Inflammatory Disease (PID)

• Cefoxitin: 2g IV q6h (plus Doxycycline 100mg PO/IV q12h)
• Cefotetan: 2g IV q12h (plus Doxycycline 100mg PO/IV q12h)

Surgical Prophylaxis (Colorectal/Appendectomy)

• Cefoxitin: 2g IV x1 (30-60 min before procedure)
• Cefotetan: 2g IV x1 (30-60 min before procedure)

Gonorrhea Uncomplicated (Alternative)

• Cefoxitin: 2g IM x 1 (plus Probenecid 1g PO x 1)

Pediatric Dosing

General (>3 Months)

• Cefoxitin:
  • 80-160 mg/kg/day IM/IV divided q4-6h
  • Max 12g/day
• Cefotetan:
  • 40-60 mg/kg/day IM/IV divided q12h
  • Max 6g/day

Appendicitis (Complicated)

• Cefoxitin: 160 mg/kg/day IV divided q6h
• Cefotetan: 40 mg/kg/day IV divided q12h

Special Populations

• Pregnancy: B
• Lactation: Safe
• Renal
  • Adult (Cefoxitin)
    • CrCl 30-50: 1-2g q8-12h
    • CrCl 10-29: 1-2g q12-24h
    • CrCl <10: 0.5-1g q24h
    • Hemodialysis: Loading dose 1-2g x1, maintenance 1-2g post-dialysis
  • Adult (Cefotetan)
    • CrCl 10-30: Give usual dose q24h
    • CrCl <10: Give usual dose q48h
    • Hemodialysis: Give 500mg supplement (or 1/4 dose) post-dialysis
  • Pediatric
    • Adjust frequency based on GFR similar to adult adjustments
• Hepatic
  • Not defined

Contraindications

• Allergy to class/drug
• History of serious hypersensitivity to penicillin

Adverse Reactions

Serious

• Anaphylaxis
• Stevens-Johnson Syndrome
• Clostridium difficile
• Hemolytic Anemia
• Hypoprothrombinemia (with bleeding) - Associated with N-MTT side chain (Cefotetan)
• Disulfiram-like reaction (with alcohol) - Associated with N-MTT side chain (Cefotetan)

Common

• Diarrhea
• Rash
• Nausea and Vomiting
• Injection site reaction (Thrombophlebitis)
• Eosinophilia
• Transaminitis

Pharmacology

• Half-life: 0.7-1h (Cefoxitin); 3-4.6h (Cefotetan)
• Metabolism: Not significantly metabolized (Cefoxitin); No metabolism (Cefotetan)
• Excretion: Urine
• Mechanism of Action: Bactericidal; inhibits cell wall mucopeptide synthesis.
• Class Distinction: Possesses 7-alpha-methoxy group which confers high stability against beta-lactamases (especially those produced by Bacteroides fragilis).

Antibiotic Sensitivities

Group	Organism	Sensitivity
Gram Positive	Strep. Group A, B, C, G	S
	Strep. Pneumoniae	S
	Viridans strep	S
	Strep. anginosus gp	S
	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+	R
	E coli/Klebsiella KPC+	R
	Enterobacter sp, AmpC neg	I
	Enterobacter sp, AmpC pos	R
	Serratia sp	R
	Serratia marcescens	R
	Salmonella sp	S
	Shigella sp	S
	Proteus mirabilis	S
	Proteus vulgaris	S
	Providencia sp.	S
	Morganella sp.	I
	Citrobacter freundii	R
	Citrobacter diversus	S
	Citrobacter sp.	I
	Aeromonas sp	I
	Acinetobacter sp.	R
	Pseudomonas aeruginosa	R
	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	X1
	Mycoplasm pneumoniae	X1
	Rickettsia sp	X1
	Mycobacterium avium	R
Anaerobes	Actinomyces	S
	Bacteroides fragilis	S
	Prevotella melaninogenica	S
	Clostridium difficile	X1
	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)
• Cephalosporins