Cefmetazole is a semi-synthetic cephamycin antibiotic, frequently classified as a second-generation cephalosporin. It is used in the treatment of various bacterial infections and is characterized by its broad spectrum of activity against both aerobic and anaerobic microorganisms.
Pharmacology and Mechanism of Action
Cefmetazole functions by inhibiting bacterial cell wall synthesis. It binds to specific penicillin-binding proteins (PBPs) located inside the bacterial cell wall, which prevents the cross-linking of peptidoglycan chains. This disruption leads to cell wall instability and subsequent bacterial cell death (bactericidal action).
Chemical Structure
As a cephamycin, cefmetazole is structurally related to cephalosporins but features a methoxy group at the 7-alpha position of the beta-lactam ring. This structural modification provides increased resistance to hydrolysis by certain beta-lactamase enzymes, particularly those produced by anaerobic bacteria. It also contains an N-methylthiotetrazole (MTT) side chain, which has been associated with specific clinical considerations, such as interference with vitamin K metabolism and potential disulfiram-like reactions when consumed with alcohol.
Antimicrobial Spectrum
The antimicrobial spectrum of cefmetazole includes:
- Gram-positive bacteria: Staphylococcus aureus (methicillin-susceptible strains), Streptococcus pyogenes, and Streptococcus pneumoniae.
- Gram-negative bacteria: Escherichia coli, Klebsiella species, Proteus mirabilis, and Haemophilus influenzae.
- Anaerobic bacteria: Significant activity against Bacteroides fragilis and other Bacteroides species, distinguishing it from many other second-generation cephalosporins.
Clinical Indications
Cefmetazole has been indicated for the treatment of infections caused by susceptible strains of microorganisms, including:
- Urinary tract infections
- Lower respiratory tract infections
- Skin and soft tissue infections
- Intra-abdominal infections
- Surgical prophylaxis, particularly for abdominal or vaginal surgeries, to reduce the incidence of post-operative infections.
Administration and Status
The drug is typically administered via intravenous or intramuscular injection. While it has been utilized globally, its availability varies by region. It was previously approved for use in the United States but was later discontinued from that market; however, it remains available in several other countries, particularly in Asia.