Cefmetazole
Pronunciation: pronunciation varies by local usage.
- Generic name
- cefmetazole
- Drug class
- Second-generation cephalosporin (cephamycin subgroup)
- Form
- Unresolved; historical study formulations included injection
- Route
- Parenteral (intravenous or intramuscular)
- Legal status
- Not verified; no current regulatory approval confirmed at time of writing
Availability and supply rules vary by country
Trade names by country:
Australia: · Full directory
What cefmetazole is and how it works
Cefmetazole is a cephamycin antibiotic (second-generation cephalosporin) that contains an N-methyl-thiotetrazole (NMTT) side chain. It was studied historically for a range of bacterial infections, but no current regulatory approval or marketed product has been confirmed. (1) (2)
This information is based on older research notes and does not represent a currently available medicine. Beta-lactam allergy, bleeding/coagulation medicines, kidney function, antibiotic-associated severe diarrhoea, and treatment decisions must be evaluated by a clinician. Do not attempt to obtain or use cefmetazole outside a formal clinical trial or authorised access programme.
Mechanism of action: how cefmetazole works
Cefmetazole is a cephamycin (second-generation cephalosporin) that inhibits bacterial cell-wall synthesis. It contains an N-methyl-thiotetrazole side chain that has been associated with coagulation effects (hypoprothrombinaemia and bleeding). (1) (2)
What cefmetazole is used for
Historical study indications
Older literature describes investigational use for gynaecologic, intra-abdominal, urinary tract, respiratory tract, skin and soft-tissue infections, and surgical prophylaxis. Current approval, availability, and dosing are not confirmed; this does not represent a current product claim. (2)
Before taking cefmetazole
Do not take / not appropriate for
- Do not receive cefmetazole if you have a known severe hypersensitivity to cefmetazole or other beta-lactam antibiotics (penicillins, cephalosporins) unless a specialist determines otherwise after individual risk assessment and consideration of alternative treatments. (all products) (1)
- Do not use cefmetazole without clinician assessment of bleeding risks, kidney function, and coagulation status; the NMTT side chain can interfere with coagulation. (all products) (1)
Tell your clinician about
- Any history of allergic reaction to beta-lactam antibiotics (penicillins, cephalosporins, or related agents).
- Bleeding disorders, use of anticoagulants or antiplatelet medicines, or unexplained bruising.
- Kidney disease or reduced kidney function.
- Previous antibiotic-associated diarrhoea or colitis.
- Pregnancy, plans for pregnancy, or breastfeeding.
- All current medicines, including over-the-counter products and supplements.
How to take cefmetazole
- Cefmetazole is given as an injection into a vein or muscle by a healthcare professional. Do not self-administer.
- Treatment decisions must be made by a specialist familiar with the patient's infection, local antibiotic resistance data, and availability; current product supplies and dosing are not confirmed.
- Do not alter the dose, frequency, or duration of treatment yourself.
Procedures and treatment changes
Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (1) (2)
Missed dose
Not applicable; the injection is given under supervision of a healthcare professional. If a dose may have been missed, the treating clinician will advise.
Overdose
If an overdose of cefmetazole injection is suspected, contact emergency services immediately. General supportive care and monitoring for adverse effects (allergic reactions, bleeding, seizures) will be needed. (1)
Side effects
Information is based on pharmacological class and historical review; no current product safety summary is available. Allergic reactions, coagulation effects, and antibiotic-associated colitis are important risks.
Injection-site reaction
What to notice: Pain, redness, swelling, or hardness at the injection site.
What to do: Tell the treatment team if severe, worsening, or accompanied by general allergic symptoms. (2)
Gastrointestinal effects
What to notice: Diarrhoea, nausea, vomiting; severe or persistent diarrhoea, especially if watery or bloody, may indicate a serious colon infection.
What to do: Notify the clinician promptly, especially if diarrhoea is severe, watery, or bloody, or accompanied by fever or abdominal pain. (2) (1)
Severe diarrhoea or suspected C. difficile colitis
What to notice: Frequent watery or bloody stools, abdominal cramps, fever, fatigue.
What to do: Seek medical attention promptly; the treating clinician will advise on whether to continue or stop treatment. (1)
Unusual bleeding or bruising
What to notice: Nosebleeds, bleeding gums, easy bruising, prolonged bleeding from cuts, blood in urine or stools.
What to do: Contact the treating clinician promptly for coagulation assessment; do not alter anticoagulant doses yourself. (1)
Allergic reaction
What to notice: Rash, hives, itching, swelling of face/lips/tongue, difficulty breathing, wheezing, faintness.
What to do: Call emergency services immediately for severe symptoms. Let the treating clinician know about any allergic symptoms. (1)
Serious warnings
Anaphylaxis or severe allergic reaction — emergency
Symptoms: Sudden difficulty breathing, throat/tongue swelling, severe hives, fast heartbeat, dizziness, loss of consciousness.
Action: Call emergency services immediately. Do not receive further doses until a specialist has evaluated the reaction. (1)
Severe colitis or C. difficile infection — urgent
Symptoms: Persistent severe diarrhoea (watery or bloody), abdominal pain, fever.
Action: Seek medical attention promptly; the clinician will assess whether treatment should be stopped and provide appropriate management. (1)
Coagulation disorder with bleeding risk — urgent
Symptoms: Spontaneous bruising, nosebleeds, bleeding gums, blood in urine/stools, excessive bleeding from minor wounds.
Action: Contact the treating clinician urgently for assessment of coagulation status; do not stop anticoagulants that were prescribed for another condition without specific medical advice. (1)
Interactions
| Medicine or test | Effect | Action |
|---|---|---|
| Anticoagulants (e.g., warfarin, heparin) | Cefmetazole contains an N-methyl-thiotetrazole side chain that can interfere with vitamin K metabolism and increase bleeding risk; combined use may significantly raise the risk of abnormal bleeding. | Close monitoring of coagulation parameters (e.g., INR) is required. Do not alter anticoagulant doses without a clinician's explicit instruction. (1) |
| Nephrotoxic medicines | Concurrent use may increase the risk of kidney toxicity; this risk may be higher in people with pre-existing kidney impairment. | Kidney function should be monitored if nephrotoxic drugs are used together with cefmetazole. (1) |
| Other beta-lactam antibiotics | Cross-allergenicity is possible; people with known hypersensitivity to penicillins or other cephalosporins may also react to cefmetazole. | Give a complete allergy history before administration. (1) |
Pregnancy, breastfeeding, kidney/liver function, age
Pregnancy and breastfeeding
No current safety data are available for pregnancy or breastfeeding. A clinician must weigh potential risks and benefits if use is contemplated, considering that no approved product exists. (2)
Children
Historical studies included paediatric use, but no current approved dosing or safety information is available for children. Do not assume that adult information applies to children. (2)
Kidney impairment
Dose adjustment is likely required in kidney impairment because cefmetazole is primarily excreted renally. However, no current product-specific guidance exists; any use must be guided by clinical judgement and renal function monitoring. (1)
Monitoring
Before starting
- Confirm the infection, bacterial susceptibility, and that a beta-lactam antibiotic is appropriate.
- Assess beta-lactam allergy history, bleeding/coagulation status, kidney function, and current medications.
- Discuss risks including allergic reaction, antibiotic-associated colitis, and coagulation effects.
During treatment
- Monitor for signs of allergic reaction at each dose.
- Monitor for diarrhoea, especially severe or bloody stools, and signs of C. difficile infection.
- Monitor coagulation parameters (e.g., INR, PT/PTT) if the patient is on anticoagulants or has risk factors for bleeding.
- Monitor kidney function regularly, especially in patients with pre-existing impairment or concurrent nephrotoxic drugs.
Storage
Storage conditions are not verified. Historically, parenteral cephalosporins require protection from light and controlled room temperature or refrigeration. Follow specific product instructions if available; do not use a product with an uncertain storage history.
Professional information
Clinician-facing context only. No current approved product or dosing information exists; any use must be based on local antibiotic guidelines and susceptibility data.
All regions
Indication: Any historical use
Dose summary: No approved, standardised dosing is available. Historical study dosing varied by indication and age; any clinical use today must be guided by a specialist with access to the most recent clinical data and antibiogram.
Renal context: Dose adjustment in renal impairment is likely necessary but specific recommendations are unresolved. Individual assessment by a clinician is essential. (2)
Hepatic guidance
No specific hepatic impairment information is available; use with caution and individual clinical judgement.
Overdose note
In case of overdose, supportive care, monitoring for allergic reactions, bleeding, and renal function is advised. Seek poison information or emergency services immediately. (1) (2)
Frequently asked questions
Is cefmetazole currently available?
No current regulatory approval or marketed product has been confirmed at the time of writing. The information here is based on historical literature. Do not attempt to obtain or use cefmetazole outside a formal clinical trial or authorised access programme. (2)
Can I take cefmetazole if I am allergic to penicillin?
Cross-reactivity is possible between penicillins and cephalosporins like cefmetazole. Do not take any beta-lactam antibiotic without a thorough assessment by a specialist, especially if you have a history of severe allergic reactions. (1)
What are the key risks with cefmetazole?
Important risks include bleeding due to interaction with coagulation (from the NMTT side chain), severe diarrhoea including C. difficile colitis, and allergic reactions. Kidney function must also be monitored. A clinician must assess all risks before use. (1)
References
- Cephalosporins - StatPearlsStatPearls Publishing, National Library of Medicine · United States · accessed 2026-08-11 · source 1
- Review of parenteral cefmetazole: antibacterial activity, pharmacokinetics, and therapeutic use (1991, PMID 2020609)PubMed, National Library of Medicine · United States · accessed 2026-08-11 · source 2
- cefmetazole — RxNorm normalized drug concept (RXCUI 2182)U.S. National Library of Medicine (RxNorm) · US · accessed 2026-08-14 · source 3
Brand names by country
Single-ingredient cefmetazole names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.