Ceftazidime
Ceftazidimum
Also known as: Fortaz · Ceptaz · Tazicef · Tazidime · Fortum · Ceftazidimum · GR-20263 · LY-139381
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Initial antibiotic therapy of gram-negative infections | 25 mg/kg | IM or SC | q8-12h | — | 🌎 NA |
| Initial treatment of orthopedic infections | 25 mg/kg | IV, IM | q8-12h | — | 🌎 NA |
| Initial treatment of soft tissue infections | 30-50 mg/kg | IV, IM | q8-12h | — | 🌎 NA |
| Initial treatment of sepsis, bacteremia | 15-30 mg/kg | IV, IM | q6-8h | — | 🌎 NA |
| Susceptible infections | 30 mg/kg | IV/IM/SC | q8h | — | 🌍 EU |
| Pseudomonas aeruginosa infections | 30 mg/kg | IV/IM/SC | q4h | — | 🌍 EU |
| Pseudomonas aeruginosa infections (CRI) | 4.4 mg/kg loading dose followed by 4.1 mg/kg/h | IV | CRI | — | 🌍 EU |
- Susceptible infections: Empirical dose; maintain tissue concentrations above MIC.
- Pseudomonas aeruginosa infections: Increased frequency required for Pseudomonas.
- Pseudomonas aeruginosa infections (CRI): Continuous rate infusion to maintain time > MIC.
Cats
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Initial treatment of systemic infections | 25-30 mg/kg | IV, IM or intraosseous | q8-12h | — | 🌎 NA |
| Susceptible infections | 30 mg/kg | IM | q8h | — | 🌍 EU |
| Pseudomonas infections | 30 mg/kg | IM | q2-4h | — | 🌍 EU |
- Susceptible infections: Empirical dose.
- Pseudomonas infections: More frequent dosing recommended for Pseudomonas.
Reptiles
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Susceptible infections | 20 mg/kg | IM or SC | q72hours (every 3 days) | — | 🌎 NA |
| Bacterial infections in snakes (particularly Enterobacteriaceae or Pseudomonas aeruginosa) | 20 mg/kg | IM | q72h | — | 🌎 NA |
| Chelonians | 50 mg/kg | IM | q24h | — | 🌎 NA |
- Bacterial infections in snakes (particularly Enterobacteriaceae or Pseudomonas aeruginosa): Maintain at 30°C
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Ceftazidime is a potent, injectable third-generation cephalosporin antibiotic primarily used to treat serious gram-negative bacterial infections, particularly those caused by susceptible Enterobacteriaceae and Pseudomonas aeruginosa.
- Broad Gram-Negative Spectrum: It is often reserved for infections resistant to other, less-expensive agents or when aminoglycosides are contraindicated due to toxicity risks.
- Exotic Animal Medicine: It is highly valued in reptile medicine due to its exceptionally long half-life in these species, allowing for infrequent dosing (e.g., every 3 days).
- Clinical Use: Typically administered parenterally (IV, IM, or SC). Subcutaneous administration is often utilized for outpatient therapy, though it requires careful client education regarding storage and handling.
Mechanism of action
Ceftazidime is a bactericidal time-dependent antibiotic.
It binds to specific penicillin-binding proteins (PBPs) located inside the bacterial cell wall → inhibits the third and final stage of bacterial cell wall synthesis (peptidoglycan cross-linking) → weakens the cell wall → leads to cell lysis and death due to osmotic instability.
Note: While it retains some gram-positive activity from earlier generations, its primary strength is its expanded gram-negative spectrum, including antipseudomonal activity.
Safety & warnings
Contraindications
- Known hypersensitivity or prior allergic reaction to cephalosporins
Adverse effects
- Pain at IM injection site (SC may be less painful)
- Gastrointestinal effects (diarrhea, vomiting)
- Hypersensitivity reactions (allergic reactions)
- Granulocytopenia
- Thrombocytopenia
- Mild azotemia
- Pseudomembranous colitis (C. difficile)
- Increased serum liver enzymes (reported in humans)
Precautions
Renal Impairment: Because the drug is primarily excreted via the kidneys, accumulation may result in patients with significantly impaired renal function. Use with caution and adjust the dose as required.
- Cross-Reactivity: Up to 16% of humans allergic to penicillins may also be allergic to cephalosporins; the veterinary significance is unclear but warrants caution.
- Laboratory Interference: May cause a false-positive urine glucose determination when using cupric sulfate solution tests (e.g., Clinitest). May rarely cause positive direct Coombs' tests.
Drug interactions
Potential additive nephrotoxicity. In vitro synergy exists against certain bacteria, but they must NOT be mixed in the same syringe or fluid bag (administer separately).
May be antagonistic to ceftazidime's bactericidal effects on gram-negative bacilli; concurrent use is not recommended.
Bacteriostatic agents may antagonize the bactericidal activity of ceftazidime.
Bacteriostatic agents may antagonize the bactericidal activity of ceftazidime.
Increased risk of nephrotoxicity when used concurrently.
Loop diuretics may increase the risk of nephrotoxicity.
Synergistic in vivo against Pseudomonas; however, chemically incompatible in vitro (do not mix in the same syringe).
Monitoring
- Clinical efficacy (resolution of infection signs)
- Baseline and ongoing renal function (BUN, Creatinine, Urinalysis)
- Injection site for signs of pain or inflammation
Pharmacokinetics
Half-life
Absorption
Not appreciably absorbed after oral administration. Must be given parenterally.
Distribution
Widely distributed throughout the body, including into bone and cerebrospinal fluid (CSF).
Metabolism
Not extensively metabolized.
Elimination
Primarily excreted unchanged by the kidneys via glomerular filtration. Renal tubular excretion does not play a major role (probenecid does not affect elimination kinetics).
Overdose
An acute overdose in patients with normal renal function is unlikely to be of great concern.
However, in patients with renal failure, overdosage of ceftazidime has caused seizures, encephalopathy, coma, neuromuscular excitability, asterixis, and myoclonia.
Treatment: Primarily symptomatic and supportive. Hemodialysis could be used to enhance elimination.
Available products
Formulations
- Powder for Injection: 500 mg, 1 g, 2 g, 6 g
- Injection (premixed, frozen): 1 g, 2 g
Human-labeled
- Ceftazidime Powder for Injection: 500 mg, 1 g, 2 g, & 6 g vials (Fortaz, Ceptaz, Tazicef, Tazidime)
- Ceftazidime Injection (premixed, frozen): 1 g & 2 g in 50 mL (Fortaz, Tazicef)
Regulatory status
Human authorized product used off-label under the Cascade. Classified as a highest priority critically important antibiotic; use is heavily restricted to cases lacking alternatives.
Human authorized product (POM) used off-label under the Cascade. Prudent use guidelines apply.
No regulatory data for: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Powders for injection: Store at 15-30°C (59-86°F) and protect from light. Frozen injection: Store at -20°C (-4°F) or lower. Reconstituted solutions (sodium carbonate formulations) effervesce (release CO2); do not allow pressure to normalize before adding diluent. Reconstituted potency: 24 hours at room temp (18h for arginine formulation), 7 days refrigerated. Frozen in plastic syringes: stable for 3 months at -20°C. Thawed solutions: stable for 8 hours at room temp, 4 days refrigerated. Do not refreeze.
Client information
- Administration: Your veterinarian may instruct you to administer this drug via subcutaneous (SC) injection at home. Ensure you are comfortable with the injection technique.
- Storage is Critical: Reconstituted ceftazidime often requires refrigeration or freezing. If dispensed in frozen syringes, keep them in the freezer until needed. Thaw only the dose you need at room temperature. Do not refreeze thawed solutions.
- Side Effects: Watch for signs of gastrointestinal upset (diarrhea, vomiting) or allergic reactions (facial swelling, hives, difficulty breathing). Contact your veterinarian if these occur.
- Injection Site: Monitor the injection site for redness, swelling, or pain.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.