Ceftazidime

Cephalosporin antibiotic (third generation) Beta-lactam antibiotic

Dosage & Administration Guidelines

Species Route Dose Frequency Duration & Clinical Notes
Dog IV, IM, SC 25-50 mg/kg q8h Duration: 7-14 days (depending on infection severity)
Notes: For severe infections, use higher end of dose range. Adjust interval in renal impairment (e.g., q12h if mild, q24h if moderate, q48h if severe).
Cat IV, IM, SC 25-50 mg/kg q8h Duration: 7-14 days
Notes: Similar to dogs; adjust for renal impairment.
Horse (adult) IV 20-40 mg/kg q6-8h Duration: 5-10 days
Notes: Administer slowly IV. For neonatal foals, dose may be higher (up to 50 mg/kg q6-8h).
Horse (foal) IV 50 mg/kg q6-8h Duration: 5-10 days
Notes: Foals have increased volume of distribution; monitor renal function.
Cattle IV, IM 20-30 mg/kg q8-12h Duration: 3-7 days
Notes: Extra-label use; observe withdrawal times. IM injection may cause tissue irritation.
Sheep/Goat IV, IM 20-30 mg/kg q8-12h Duration: 3-7 days
Notes: Extra-label use; withdrawal times not established.
Rabbit SC, IM, IV 25-50 mg/kg q8-12h Duration: 7-14 days
Notes: Use cautiously in rabbits due to risk of gastrointestinal dysbiosis; ensure adequate hydration.
Reptiles IM, SC 20-50 mg/kg q24-72h Duration: 7-14 days
Notes: Dosing interval depends on species and temperature; lower frequency in cooler environments.

Clinical Indications & Species Uses

General Indications
  • Treatment of infections caused by ceftazidime-susceptible organisms, especially Pseudomonas aeruginosa and other multidrug-resistant Gram-negative bacteria
  • Empiric therapy for severe nosocomial infections in hospitalized animals when Pseudomonas is suspected
Dog (Canine)
  • Treatment of infections caused by susceptible Gram-negative bacteria, particularly Pseudomonas aeruginosa, in dogs
  • Septicemia
  • Pneumonia
  • Urinary tract infections (complicated)
  • Skin and soft tissue infections
  • Bone and joint infections
  • Intra-abdominal infections (in combination with metronidazole or clindamycin for anaerobic coverage)
Cat (Feline)
  • Treatment of infections caused by susceptible Gram-negative bacteria, particularly Pseudomonas aeruginosa, in cats
  • Septicemia
  • Pneumonia
  • Urinary tract infections (complicated)
  • Skin and soft tissue infections
  • Intra-abdominal infections (in combination with metronidazole or clindamycin)
Horse (Equine)
  • Treatment of Gram-negative infections, especially Pseudomonas aeruginosa, in adult horses and foals
  • Septicemia in neonates
  • Pneumonia
  • Metritis
  • Wound infections
  • Osteomyelitis
Cattle (Bovine)
  • Treatment of Gram-negative infections, including pneumonia and septicemia, in cattle (extra-label use)
  • Metritis
Small Ruminants (Sheep / Goat)
  • Treatment of Gram-negative infections in sheep and goats (extra-label use)
  • Pneumonia
  • Septicemia
Rabbit & Small Mammals
  • Treatment of susceptible Gram-negative infections, particularly Pseudomonas aeruginosa, in rabbits
  • Respiratory infections
  • Abscesses (in combination with surgical drainage)
Exotic & Other Species
  • Reptiles: Treatment of Gram-negative infections, including abscesses and septicemia
  • Small mammals (ferrets, guinea pigs): Treatment of susceptible infections

Pharmacology & Mechanism of Action

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

Mechanism of Action: Ceftazidime is a bactericidal beta-lactam antibiotic that inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), particularly PBP-3, leading to disruption of peptidoglycan cross-linking and eventual cell lysis. Its aminothiazolyl side chain and iminomethoxy group confer enhanced stability against many beta-lactamases, including extended-spectrum beta-lactamases (ESBLs) produced by Gram-negative bacteria, while its carboxypropyl group provides potent activity against Pseudomonas aeruginosa.

Pharmacodynamics: Ceftazidime exhibits time-dependent killing, with efficacy correlated with the time the free drug concentration remains above the minimum inhibitory concentration (MIC) for the pathogen. It has a broad spectrum of activity against Gram-negative aerobes, including Pseudomonas aeruginosa, Enterobacteriaceae (e.g., Escherichia coli, Klebsiella pneumoniae), and Haemophilus spp., as well as moderate activity against Gram-positive cocci (e.g., Staphylococcus aureus, Streptococcus spp.) but is less potent against Gram-positives compared to first-generation cephalosporins. It is inactive against anaerobes, Enterococcus spp., and methicillin-resistant staphylococci.

⚡ Pharmacokinetics Summary

Absorption: Ceftazidime is poorly absorbed after oral administration; therefore, it is administered parenterally (IV or IM). After IM injection, absorption is rapid and complete, with peak plasma concentrations achieved within 1-2 hours.
Distribution: Ceftazidime is widely distributed into body fluids and tissues, including pleural, peritoneal, synovial, and cerebrospinal fluids (especially when meninges are inflamed). It crosses the placenta and is excreted in milk. Volume of distribution is approximately 0.2-0.3 L/kg in dogs and cats.
Metabolism: Ceftazidime undergoes minimal hepatic metabolism; the majority of the drug is excreted unchanged by the kidneys via glomerular filtration and tubular secretion.
Excretion: Ceftazidime is primarily eliminated unchanged in the urine via glomerular filtration and active tubular secretion. In animals with normal renal function, approximately 80-90% of the dose is recovered in urine within 24 hours. Biliary excretion is minimal.
Half-Life: Dogs: 1.1-1.5 hours; Cats: 1.5-2.0 hours; Horses: 1.5-2.5 hours; Cattle: 2-3 hours; Humans: 1.5-2 hours. Half-life is prolonged in animals with renal impairment.
Bioavailability: Oral bioavailability is negligible (<5%); IM bioavailability is nearly 100%.
Protein Binding: Ceftazidime is approximately 10-20% bound to plasma proteins in most species.

Available Formulations & Strengths

Injectable Solution (powder for reconstitution) 500 mg, 1 g, 2 g vials (reconstitute to 100-200 mg/mL) (IV, IM, SC)

Contraindications & Clinical Warnings

Contraindications:
  • Known hypersensitivity to ceftazidime, other cephalosporins, or 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 dosage is adjusted
Warnings & Clinical Precautions:
  • Use with caution in animals with renal impairment; adjust dose or interval.
  • Prolonged use may result in overgrowth of non-susceptible organisms (e.g., Enterococcus, Candida).
  • May cause injection site pain or phlebitis; administer IV slowly.
  • In herbivores (rabbits, horses, cattle), monitor for signs of gastrointestinal upset or dysbiosis.
  • Use in pregnant or lactating animals only if clearly needed; safety not fully established.
  • Extra-label use in food animals requires veterinary oversight and extended withdrawal times.

Adverse Effects & Reactions

Common:

  • Injection site pain or swelling
  • Gastrointestinal disturbances (nausea, vomiting, diarrhea) in some species
  • Hypersensitivity reactions (skin rash, urticaria)

Serious / Severe:

  • Anaphylaxis (rare but potentially fatal)
  • Acute renal injury (especially with concurrent nephrotoxic drugs)
  • Clostridioides difficile-associated diarrhea (colitis) in some species
  • Neurological signs (seizures, encephalopathy) in overdose or renal failure

Rare:

  • Bone marrow suppression (neutropenia, thrombocytopenia)
  • Elevated liver enzymes
  • Coagulation abnormalities (hypoprothrombinemia)
  • Superinfection with resistant organisms

Key Drug Interactions

Interacting Drug / Class Clinical Effect & Mechanism Severity
Aminoglycosides (e.g., gentamicin, amikacin) Additive or synergistic antibacterial activity; increased risk of nephrotoxicity if used concurrently. Moderate
Loop diuretics (e.g., furosemide) Increased risk of nephrotoxicity and ototoxicity. Moderate
Probenecid Decreases renal tubular secretion of ceftazidime, increasing plasma concentrations and risk of toxicity. Moderate
Chloramphenicol Potential antagonism of bactericidal activity (bacteriostatic vs. bactericidal). Mild
Tetracyclines Potential antagonism of bactericidal activity. Mild

Overdose & Toxicity Management

Signs of Toxicity:

  • Seizures
  • Encephalopathy
  • Neuromuscular irritability
  • Nausea and vomiting
  • Diarrhea

Emergency Treatment Protocol: There is no specific antidote. Treatment is symptomatic and supportive. In cases of recent oral ingestion (unlikely due to poor absorption), consider gastric decontamination. For parenteral overdose, discontinue the drug, provide fluid therapy to enhance renal excretion, and manage seizures with diazepam or barbiturates. Hemodialysis may be effective in severe cases, especially in animals with renal impairment.

Food Animal Withdrawal Times

🥩 Meat: 7 days🥛 Milk: 4 days

Withdrawal times for ceftazidime are not officially established in many countries; the values provided are conservative estimates for extra-label use in cattle and sheep. For poultry, do not use in laying hens if eggs are for human consumption. Always consult regulatory guidelines and use the longest withdrawal period when in doubt.

Storage, Handling & Regulatory Information

Storage Temperature: Store powder at 20-25°C (68-77°F); reconstituted solution is stable for 24 hours at room temperature or 7 days under refrigeration (2-8°C).

Handling & Special Conditions: Protect from moisture. Do not freeze reconstituted solution. Discard unused portions after the stated stability period.

Dispensing Status: Prescription Required (Rx Only)

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

Extra-Label (Off-Label) Use: In the US, extra-label use of ceftazidime in food animals is prohibited by the Animal Medicinal Drug Use Clarification Act (AMDUCA) because it is a cephalosporin of importance in human medicine. Use in food animals is not permitted except under specific conditions (e.g., limited to certain routes and indications). In companion animals, extra-label use is allowed under veterinary supervision.

Clinical Pearls & Practice Notes

💡 Clinical Insights: Ceftazidime is a valuable third-generation cephalosporin for treating infections caused by Pseudomonas aeruginosa and other multidrug-resistant Gram-negative bacteria in veterinary patients. It is particularly useful in hospital-acquired infections, septicemia, and infections in immunocompromised animals. Because of its poor oral bioavailability, it must be administered parenterally. Dosing frequency is typically every 8 hours in dogs and cats, but may need adjustment in renal impairment. In food animals, its use is highly restricted due to regulatory concerns; alternative antibiotics should be considered. Always perform culture and sensitivity testing when possible to ensure appropriate use and to minimize the development of resistance. Monitor renal function during therapy, especially in critically ill animals or those receiving concurrent nephrotoxic drugs.

References & Literature

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