Cefoxitin

BRAND NAMES

The primary brand name for the antibiotic cefoxitin is Mefoxin. While Mefoxin has been discontinued in the U.S., generic versions of cefoxitin are widely available. 

Other brand names for cefoxitin include: 

• Renoxitin

• Cefoxitin Juno (marketed in Australia)

MECHANISM OF ACTION

Cefotaxime is a bactericidal antibiotic that works by binding to penicillin-binding proteins (PBPs) through its beta-lactam ring, thereby inhibiting the transpeptidation step in peptidoglycan cell wall synthesis of susceptible bacteria. This disruption weakens the bacterial cell wall, leading to cell lysis and death.

PHARMACOKINETICS:

Absorption

Cefoxitin is not absorbed orally and must be administered by intravenous (IV) or intramuscular (IM) injection. After IM administration, peak plasma concentrations are typically reached within 30 to 60 minutes.

Distribution

Cefoxitin is widely distributed throughout body tissues and fluids, including the lungs, liver, kidneys, bones, and bile. It also achieves therapeutic concentrations in the cerebrospinal fluid (CSF) when the meninges are inflamed. Protein binding ranges from 65% to 85%.

Metabolism

Cefoxitin undergoes minimal metabolism in the body, remaining largely unchanged during its circulation.

Excretion

The drug is primarily excreted unchanged in the urine through glomerular filtration and tubular secretion. Approximately 85% of the dose is recovered in the urine within 6 hours, with a plasma half-life of about 45 to 60 minutes in patients with normal kidney function. Dosage adjustment is required in renal impairment.

PHARMACODYNAMICS

Cefoxitin is a cephamycin antibiotic commonly classified with second-generation cephalosporins. It exhibits broad-spectrum activity against gram-negative and anaerobic bacteria. The presence of a methoxy group at the 7α position gives cefoxitin enhanced resistance to beta-lactamases, including both penicillinases and cephalosporinases produced by gram-negative organisms.

ADMINISTRATION

Cefoxitin is administered parenterally, either by intravenous (IV) infusion or intramuscular (IM) injection. For IV use, the medication should be reconstituted and diluted according to manufacturer guidelines and infused slowly over 3 to 5 minutes (direct IV) or over 15 to 30 minutes (intermittent infusion) to avoid vein irritation. IM injections are typically given deep into a large muscle, such as the gluteal muscle, to minimize discomfort. The dosage, route, and duration of therapy depend on the type and severity of infection, as well as the patient’s renal function. It is essential that cefoxitin administration be performed under the supervision of a healthcare professional using sterile technique.

DOSAGE AND STRENGTH

Cefoxitin is available as an injectable antibiotic, supplied either as a powder for reconstitution or as a pre-mixed solution for intravenous (IV) or intramuscular (IM) administration, in strengths of 1 g and 2 g vials. The dosage varies based on the severity and type of infection, as well as the patient’s age, weight, and renal function. For adults, the usual dose is 1–2 g every 6 to 8 hours, while severe infections may require up to 12 g per day, divided into multiple doses. In pediatric patients, the recommended dosage is 80–160 mg/kg per day, given in divided doses every 6 to 8 hours. In cases of renal impairment, dose adjustments are essential to prevent accumulation and toxicity. All dosing regimens should be prescribed and supervised by a qualified healthcare professional.

DRUG INTERACTIONS

Cefoxitin can interact with several medications, potentially affecting its effectiveness or increasing the risk of side effects:

• Aminoglycosides (e.g., gentamicin, tobramycin): Concurrent use may heighten the risk of kidney toxicity.

• Diuretics (e.g., furosemide): May also increase the likelihood of renal impairment when used together.

• Oral anticoagulants (e.g., warfarin): Cefoxitin may enhance anticoagulant effects, raising the risk of bleeding; regular monitoring of blood clotting parameters is advised.

• Probenecid: Delays the renal excretion of cefoxitin, leading to higher and prolonged blood levels of the drug.

• Oral contraceptives: Like many antibiotics, cefoxitin may reduce their effectiveness, so additional contraceptive measures may be needed.

FOOD INTERACTIONS

There are no significant food interactions associated with cefoxitin, as it is administered by injection and not absorbed through the digestive system, making dietary interactions unlikely. However, some sources recommend exercising caution with certain substances.

CONTRAINDICATIONS

Cefoxitin is contraindicated in individuals with a known allergy to the drug, its components, or other cephalosporin antibiotics. Due to the structural similarity between cephalosporins and penicillins, patients with a history of severe penicillin allergies should be treated with caution and closely monitored.

SIDE EFFECTS

Common Side Effects

These side effects usually improve as your body adapts to the medication:

• Injection site reactions: Pain, redness, swelling, or tenderness at the injection area.

• Gastrointestinal issues: Mild nausea, vomiting, diarrhea, or stomach discomfort.

• Skin reactions: Itching or rashes.

• Other effects: Headache and fever.

Serious Side Effects

• Severe gastrointestinal issues

• Allergic reactions

• Severe skin reactions

• Blood disorders

• Kidney problems

• Liver issues

• Neurological effects

OVER DOSE

An overdose of cefoxitin, a cephalosporin antibiotic, can lead to several adverse effects. Key points include:

• Gastrointestinal disturbances: Nausea, vomiting, diarrhea, and abdominal discomfort may occur.

• Electrolyte imbalance: High doses can cause changes in potassium levels or metabolic disturbances.

• Neurological effects: Rarely, high doses may trigger seizures or confusion, especially in patients with kidney impairment.

• Allergic reactions: Symptoms such as rash, itching, or more severe hypersensitivity reactions may appear.

• Management: Primarily supportive care, including discontinuation of the drug, monitoring of vital signs, hydration, and in severe cases, hemodialysis for renal impairment.

TOXICITY

The acute intravenous LD₅₀ of captopril was approximately 8.0 g/kg in adult female mice and over 1.0 g/kg in rabbits. In adult rats, the acute intraperitoneal LD₅₀ exceeded 10.0 g/kg.