Cefotaxime Sodium — Veterinary Vademecum Drug Reference

Dosage & Administration Guidelines

Species	Route	Dose	Frequency	Duration & Clinical Notes
Dog	IV, IM, SC	20-40 mg/kg	q8h	Duration: 5-7 days or as clinically indicated Notes: For severe infections, higher doses (up to 50 mg/kg) may be used. Administer slowly IV over 3-5 minutes.
Cat	IV, IM, SC	20-40 mg/kg	q8h	Duration: 5-7 days or as clinically indicated Notes: For severe infections, higher doses (up to 50 mg/kg) may be used. Administer slowly IV over 3-5 minutes.
Horse	IV, IM	20-30 mg/kg	q6-8h	Duration: 5-7 days or as clinically indicated Notes: Administer IV slowly. IM injections may cause pain and tissue irritation.
Cattle	IV, IM	20-30 mg/kg	q8-12h	Duration: 5-7 days or as clinically indicated Notes: Extra-label use in food animals requires veterinary oversight and extended withdrawal times.
Small Ruminants (sheep, goats)	IV, IM	20-30 mg/kg	q8-12h	Duration: 5-7 days or as clinically indicated Notes: Extra-label use in food animals requires veterinary oversight and extended withdrawal times.
Rabbit	IV, IM, SC	25-50 mg/kg	q8-12h	Duration: 5-7 days or as clinically indicated Notes: Use cautiously in rabbits due to potential gastrointestinal flora disruption.
Birds/Poultry	IM, IV	50-100 mg/kg	q6-8h	Duration: 5-7 days or as clinically indicated Notes: Not commonly used in poultry; extra-label use requires withdrawal time considerations.
Exotic/Other	IV, IM, SC	Varies by species; often 20-50 mg/kg	q8-12h	Duration: 5-7 days or as clinically indicated Notes: Dose based on published references and sensitivity testing.

Clinical Indications & Species Uses

General Indications

Treatment of serious bacterial infections caused by susceptible Gram-positive and Gram-negative organisms, particularly those resistant to first-generation cephalosporins.

Dog (Canine)

Treatment of bacterial infections caused by susceptible organisms, including respiratory tract infections, urinary tract infections, skin and soft tissue infections, septicemia, and meningitis.

Cat (Feline)

Treatment of bacterial infections caused by susceptible organisms, including respiratory tract infections, urinary tract infections, skin and soft tissue infections, septicemia, and meningitis.

Horse (Equine)

Treatment of bacterial infections caused by susceptible organisms, including respiratory tract infections, septicemia, and infections of the musculoskeletal system.

Rabbit & Small Mammals

Treatment of bacterial infections caused by susceptible organisms, including respiratory tract infections and septicemia.

Exotic & Other Species

Treatment of bacterial infections in exotic animals (e.g., reptiles, small mammals) caused by susceptible organisms, based on culture and sensitivity.

Pharmacology & Mechanism of Action

Drug Class: Cephalosporin antibiotic (third generation) | Pharmacological Group: Beta-lactam antibiotic

Mechanism of Action: Cefotaxime is a third-generation cephalosporin that exerts its bactericidal effect by inhibiting bacterial cell wall synthesis. It binds to penicillin-binding proteins (PBPs) located on the bacterial cell wall, interfering with the transpeptidation reaction essential for cross-linking peptidoglycan chains. This leads to a weakened cell wall, osmotic instability, and eventual cell lysis. Cefotaxime is stable against many beta-lactamases, particularly those produced by Gram-negative bacteria, which contributes to its broad-spectrum activity.

Pharmacodynamics: Cefotaxime exhibits time-dependent bactericidal activity. Its efficacy is best correlated with the duration of time that the drug concentration remains above the minimum inhibitory concentration (MIC) for the infecting organism. It has excellent activity against many Gram-negative pathogens including Escherichia coli, Klebsiella spp., Proteus mirabilis, and Haemophilus spp., as well as Gram-positive organisms such as Streptococcus spp. and methicillin-susceptible Staphylococcus spp. It is less active against anaerobes and Pseudomonas aeruginosa. The active metabolite, desacetylcefotaxime, contributes to the antibacterial effect, particularly against Gram-negative bacteria.

⚡ Pharmacokinetics Summary

Absorption: Cefotaxime is not absorbed orally and must be administered parenterally. After intramuscular (IM) or subcutaneous (SC) injection, absorption is rapid and complete. Peak plasma concentrations are achieved within 30-60 minutes after IM administration.

Distribution: Cefotaxime is widely distributed into body tissues and fluids, including pleural, peritoneal, synovial, and cerebrospinal fluids (especially when meninges are inflamed). It crosses the placenta and is distributed into milk. The volume of distribution is approximately 0.2-0.4 L/kg in most species.

Metabolism: Cefotaxime is partially metabolized in the liver to desacetylcefotaxime, which retains antibacterial activity and is approximately 10-fold less potent than the parent drug. The metabolism is not extensive, and the majority of the drug is excreted unchanged.

Excretion: Cefotaxime and its metabolites are primarily eliminated by the kidneys via glomerular filtration and tubular secretion. In animals with normal renal function, approximately 50-80% of the dose is excreted unchanged in the urine within 24 hours. Biliary excretion is a minor pathway.

Half-Life: The elimination half-life is short, typically 0.5-1 hour in dogs and cats, 0.5-1.5 hours in horses, and 0.5-1 hour in cattle. In neonates or animals with renal impairment, the half-life may be prolonged.

Bioavailability: Oral bioavailability is negligible; therefore, the drug must be given parenterally. IM and SC routes provide complete bioavailability.

Protein Binding: Cefotaxime is approximately 30-50% bound to plasma proteins in most species.

Available Formulations & Strengths

Injectable Solution (powder for reconstitution) 1 g, 2 g vials; reconstitute to 100 mg/mL or 200 mg/mL (IV, IM, SC)

Contraindications & Clinical Warnings

Contraindications:

Known hypersensitivity to cephalosporins or other beta-lactam antibiotics.
Use in animals with a history of anaphylactic reactions to penicillins (cross-reactivity may occur).
Do not use in animals with severe renal impairment unless dose adjustment is made.

Warnings & Clinical Precautions:

Use with caution in animals with a history of allergic reactions to penicillins or other beta-lactams.
Prolonged use may result in overgrowth of non-susceptible organisms, including Clostridioides difficile.
In food animals, extra-label use is prohibited unless under veterinary supervision with appropriate withdrawal times.
Administer IV slowly to avoid adverse reactions.
Reconstituted solutions should be used within 24 hours if stored at room temperature or 7 days if refrigerated.
Use with caution in neonates and animals with renal or hepatic impairment; dose adjustment may be necessary.

Adverse Effects & Reactions

Common:

Pain at injection site
Swelling at injection site
Gastrointestinal upset (vomiting, diarrhea)

Serious / Severe:

Anaphylaxis
Acute renal injury
Clostridioides difficile-associated diarrhea
Seizures (especially with high doses or renal impairment)

Rare:

Bone marrow suppression
Hepatotoxicity
Coagulopathy
Allergic interstitial nephritis

Key Drug Interactions

Interacting Drug / Class	Clinical Effect & Mechanism	Severity
Aminoglycosides (e.g., gentamicin)	Additive nephrotoxicity; monitor renal function.	High
Loop diuretics (e.g., furosemide)	Increased risk of nephrotoxicity.	Moderate
Probenecid	Decreases renal tubular secretion of cefotaxime, increasing plasma concentrations and risk of toxicity.	Moderate
Warfarin and other anticoagulants	May enhance anticoagulant effect; monitor coagulation parameters.	Moderate
Bacteriostatic antibiotics (e.g., tetracyclines, macrolides)	Potential antagonism of bactericidal activity; avoid concurrent use.	Mild

Overdose & Toxicity Management

Signs of Toxicity:

Seizures
Neuromuscular excitability
Nausea and vomiting
Diarrhea
Acute renal failure (with massive overdose)

Emergency Treatment Protocol: There is no specific antidote. Treatment is symptomatic and supportive. Induce emesis if recent oral ingestion (though not applicable as parenteral). Administer IV fluids to maintain diuresis and enhance renal excretion. In severe cases, hemodialysis may be considered. Monitor renal function and neurological status. Anticonvulsants (e.g., diazepam) may be used to control seizures.

Food Animal Withdrawal Times

🥩 Meat: 5 days🥛 Milk: 3 days

Withdrawal times are not established for cefotaxime in food animals; extra-label use requires extended withdrawal periods. Consult FARAD (Food Animal Residue Avoidance Databank) for specific recommendations.

Storage, Handling & Regulatory Information

Storage Temperature: Store powder at controlled room temperature (20-25°C). Reconstituted solution may be stored refrigerated (2-8°C) for up to 7 days or at room temperature for 24 hours.

Handling & Special Conditions: Protect from freezing. Use reconstituted solutions within the specified time; discard unused portions.

Dispensing Status: Prescription Required (Rx Only)

Approval Status: Cefotaxime is not FDA-approved for veterinary use in the US; it is used extra-label in veterinary medicine.

Extra-Label (Off-Label) Use: In the US, extra-label use of cefotaxime in food animals is prohibited under AMDUCA unless there is no approved drug available and a valid veterinarian-client-patient relationship exists. Extended withdrawal times must be observed.

Clinical Pearls & Practice Notes

💡 Clinical Insights: Cefotaxime is a valuable third-generation cephalosporin for treating serious infections in companion animals, especially when resistance to first-generation cephalosporins is suspected. It is particularly useful for Gram-negative infections, including those involving the central nervous system due to good CSF penetration. However, its short half-life necessitates frequent dosing (q8h). In food animals, its use is limited by withdrawal times and extra-label restrictions. Always perform culture and sensitivity testing when possible. Monitor renal function during therapy, especially in critically ill animals. Administer IV slowly to minimize adverse effects.

References & Literature

📚 Plumb's Veterinary Drug Handbook
📚 Papich Veterinary Pharmacology and Therapeutics
📚 Compendium of Veterinary Products (CVP)