Celecoxib

NSAID (Nonsteroidal Anti-inflammatory Drug) Coxib (COX-2 selective inhibitor)

Dosage & Administration Guidelines

Species Route Dose Frequency Duration & Clinical Notes
Dog PO 2-4 mg/kg q24h Duration: Variable; for osteoarthritis, long-term as needed; for post-operative pain, 3-7 days
Notes: Administer with food to reduce GI upset. Use lowest effective dose for shortest duration.
Cat PO 1-2 mg/kg q24h Duration: Short-term (up to 5 days) for acute pain; for chronic osteoarthritis, use with caution and monitor renal function
Notes: Off-label use; cats are more sensitive to NSAIDs, use with caution and monitor for GI and renal adverse effects.
Horse PO 2 mg/kg q12-24h Duration: Short-term (3-5 days)
Notes: Limited data; not approved. Use only if other NSAIDs are not available.
Cattle PO Not established Not established Duration: Not established
Notes: Not recommended due to lack of data and withdrawal times.
Small Ruminants PO Not established Not established Duration: Not established
Notes: Not recommended due to lack of data.
Rabbit PO 5-10 mg/kg q24h Duration: Short-term (3-5 days)
Notes: Off-label; use with caution due to GI sensitivity.
Bird/Poultry PO Not established Not established Duration: Not established
Notes: Not recommended due to lack of data.
Exotic/Other PO Not established Not established Duration: Not established
Notes: Use only with specialist guidance.

Clinical Indications & Species Uses

General Indications
  • Pain and inflammation associated with osteoarthritis
  • Post-operative pain management
Dog (Canine)
  • Osteoarthritis
  • Post-operative pain and inflammation
  • Acute musculoskeletal pain
Cat (Feline)
  • Osteoarthritis (off-label use)
  • Post-operative pain (off-label use)

Pharmacology & Mechanism of Action

Drug Class: NSAID (Nonsteroidal Anti-inflammatory Drug) | Pharmacological Group: Coxib (COX-2 selective inhibitor)

Mechanism of Action: Celecoxib selectively inhibits cyclooxygenase-2 (COX-2), the enzyme responsible for prostaglandin synthesis at sites of inflammation, while sparing cyclooxygenase-1 (COX-1) at therapeutic concentrations. This selectivity reduces the production of pro-inflammatory prostaglandins (e.g., PGE2) without significantly affecting the gastroprotective prostaglandins (e.g., PGI2) and thromboxane A2, thereby providing anti-inflammatory, analgesic, and antipyretic effects with a lower risk of gastrointestinal ulceration compared to non-selective NSAIDs.

Pharmacodynamics: Celecoxib exhibits dose-dependent anti-inflammatory, analgesic, and antipyretic activity. In animal models, it reduces edema, pain behaviors, and fever. Its COX-2 selectivity varies by species; in dogs, it is approximately 10-fold selective for COX-2 over COX-1, while in cats, selectivity is lower. Celecoxib does not inhibit platelet aggregation at therapeutic doses and has minimal effects on renal hemodynamics in healthy animals, but may affect renal function in dehydrated or hypotensive patients.

⚡ Pharmacokinetics Summary

Absorption: Celecoxib is well absorbed after oral administration. In dogs, peak plasma concentrations occur approximately 1-2 hours after dosing. Food increases absorption and reduces variability. In cats, absorption is slower, with peak concentrations at 2-4 hours.
Distribution: Celecoxib is highly protein-bound (>97%) in plasma. It distributes widely into tissues, with high concentrations in synovial fluid, reaching approximately 50% of plasma concentrations. Volume of distribution is low to moderate.
Metabolism: Celecoxib is extensively metabolized in the liver, primarily by cytochrome P450 enzymes (CYP2C9 in humans; in animals, similar CYP isoforms). Metabolism involves oxidation to hydroxycelecoxib and subsequent conjugation to glucuronide. There is enterohepatic recirculation.
Excretion: Celecoxib is excreted primarily in feces (about 57%) and urine (about 27%) as metabolites. In dogs, the elimination half-life is approximately 4-6 hours; in cats, it is longer, around 8-12 hours.
Half-Life: Dog: 4-6 hours; Cat: 8-12 hours; Horse: ~2-4 hours (limited data); Cattle: ~3-5 hours (limited data)
Bioavailability: Oral bioavailability is approximately 70-80% in dogs and cats, with food increasing absorption.
Protein Binding: >97% in dogs and cats

Available Formulations & Strengths

Oral Capsule 50 mg, 100 mg, 200 mg (PO)
Oral Tablet 50 mg, 100 mg, 200 mg (PO)

Contraindications & Clinical Warnings

Contraindications:
  • Known hypersensitivity to celecoxib or other sulfonamides
  • Active gastrointestinal ulceration or bleeding
  • Renal or hepatic impairment (severe)
  • Dehydration, hypovolemia, or hypotension
  • Concurrent use with other NSAIDs or corticosteroids
  • Pregnancy (especially late gestation) and lactation (unless benefits outweigh risks)
  • Use in animals with bleeding disorders
Warnings & Clinical Precautions:
  • Use with caution in animals with pre-existing renal, hepatic, or cardiac disease.
  • Monitor renal function and hydration status during therapy, especially in geriatric animals.
  • Administer with food to reduce gastrointestinal adverse effects.
  • Do not exceed recommended dose or duration.
  • In cats, use only short-term and with close monitoring due to increased sensitivity.
  • Avoid use in animals with a history of gastrointestinal ulceration.
  • Use with caution in animals receiving anticoagulants or antiplatelet agents.
  • Not for use in food animals due to lack of withdrawal times and potential for human exposure.

Adverse Effects & Reactions

Common:

  • Gastrointestinal upset (vomiting, diarrhea, decreased appetite)
  • Lethargy
  • Increased liver enzymes (transient)

Serious / Severe:

  • Gastrointestinal ulceration or perforation
  • Renal toxicity (acute kidney injury)
  • Hepatotoxicity
  • Bleeding disorders
  • Hypersensitivity reactions (anaphylaxis)

Rare:

  • Bone marrow suppression
  • Cutaneous reactions (e.g., Stevens-Johnson syndrome)
  • Neurological signs (seizures, ataxia)

Key Drug Interactions

Interacting Drug / Class Clinical Effect & Mechanism Severity
Other NSAIDs (e.g., carprofen, meloxicam) Increased risk of gastrointestinal ulceration and renal toxicity High
Corticosteroids (e.g., prednisone) Increased risk of gastrointestinal ulceration and renal toxicity High
Anticoagulants (e.g., warfarin, heparin) Increased risk of bleeding High
ACE inhibitors (e.g., enalapril) Reduced antihypertensive effect and increased risk of renal dysfunction Moderate
Diuretics (e.g., furosemide) Reduced diuretic effect and increased risk of renal toxicity Moderate
Cyclosporine Increased risk of nephrotoxicity Moderate
Fluconazole or other CYP2C9 inhibitors Increased celecoxib plasma concentrations Moderate

Overdose & Toxicity Management

Signs of Toxicity:

  • Vomiting
  • Diarrhea
  • Lethargy
  • Loss of appetite
  • Abdominal pain
  • Melena
  • Acute kidney injury (oliguria, azotemia)
  • Hepatic dysfunction
  • Seizures (in severe cases)

Emergency Treatment Protocol: Induce emesis if within 2 hours of ingestion and the animal is conscious. Administer activated charcoal to reduce absorption. Provide symptomatic and supportive care: intravenous fluids to maintain hydration and renal perfusion, gastroprotective agents (e.g., sucralfate, H2 antagonists, proton pump inhibitors), monitoring of renal and hepatic function, and treatment of seizures if they occur. In severe cases, consider hemodialysis or peritoneal dialysis.

Food Animal Withdrawal Times

Celecoxib is not approved for use in food animals. No withdrawal times have been established. Do not use in animals intended for food production.

Storage, Handling & Regulatory Information

Storage Temperature: Store at controlled room temperature 20-25°C (68-77°F), excursions permitted between 15-30°C (59-86°F).

Handling & Special Conditions: Protect from moisture. Keep in original container with desiccant.

Dispensing Status: Prescription Required (Rx Only)

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

Extra-Label (Off-Label) Use: In the US, extra-label use of celecoxib in animals is permitted under AMDUCA (Animal Medicinal Drug Use Clarification Act) only by or on the order of a licensed veterinarian within a valid veterinarian-client-patient relationship. However, it is prohibited in food-producing animals due to lack of withdrawal times and potential for human exposure.

Clinical Pearls & Practice Notes

💡 Clinical Insights: Celecoxib is a selective COX-2 inhibitor used primarily in dogs for the management of osteoarthritis and post-operative pain. It offers the advantage of a lower risk of gastrointestinal ulceration compared to non-selective NSAIDs, but it is not without risks. In cats, its use is off-label and should be limited to short-term therapy due to their unique metabolism and sensitivity to NSAIDs. Always assess renal and hepatic function before initiating therapy, especially in geriatric patients. Administer with food to minimize GI upset. Monitor for adverse effects, particularly gastrointestinal signs and changes in renal function. Avoid concurrent use with other NSAIDs or corticosteroids. Due to lack of safety data, celecoxib should not be used in food animals. For chronic pain management, consider a multimodal approach including non-pharmacological therapies and regular re-evaluation.

References & Literature

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