Carprofen

Nonsteroidal Anti-inflammatory Drug (NSAID) Propionic acid derivative

Dosage & Administration Guidelines

Species Route Dose Frequency Duration & Clinical Notes
Dog Oral (PO) 2.2 mg/kg (1 mg/lb) Every 12 hours (q12h) Duration: For osteoarthritis: as needed, typically 2-4 weeks; for postoperative pain: 2-3 days
Notes: Alternatively, 4.4 mg/kg (2 mg/lb) once daily (q24h). Administer with food to reduce GI upset.
Dog Subcutaneous (SC) or Intravenous (IV) 4.4 mg/kg (2 mg/lb) Once daily (q24h) Duration: For postoperative pain: up to 3 days
Notes: Injectable formulation is for single-dose use; may be repeated once after 24 hours if needed.
Cat Oral (PO) Not recommended; if used off-label, 2-4 mg/kg once daily (q24h) with extreme caution Once daily (q24h) Duration: Short-term only (1-3 days) due to prolonged half-life
Notes: Cats have a long half-life (~19 hours) and are more prone to toxicity. Use only if no alternative is available.
Horse Oral (PO) or Intravenous (IV) 0.7 mg/kg (0.3 mg/lb) Once daily (q24h) Duration: For musculoskeletal pain: 3-5 days; may be repeated as needed
Notes: IV formulation is for single use; oral paste or granules are available. Not approved for use in horses intended for human consumption.
Cattle Not applicable Not applicable Not applicable Duration: Not applicable
Notes: Not approved for use in cattle; contraindicated in food animals.
Small Ruminants Not applicable Not applicable Not applicable Duration: Not applicable
Notes: Not approved; off-label use is not recommended.
Rabbit Oral (PO) 2-4 mg/kg Every 12-24 hours (q12-24h) Duration: Short-term (1-3 days)
Notes: Off-label use; monitor for GI stasis and renal function.
Bird/Poultry Not applicable Not applicable Not applicable Duration: Not applicable
Notes: Not approved; use is not recommended.
Exotic/Other Not applicable Not applicable Not applicable Duration: Not applicable
Notes: Not approved; use should be based on species-specific literature.

Clinical Indications & Species Uses

General Indications
  • Pain and inflammation management in dogs and horses
Dog (Canine)
  • Relief of pain and inflammation associated with osteoarthritis
  • Management of postoperative pain and inflammation following soft tissue and orthopedic surgery
  • Control of acute musculoskeletal pain
Horse (Equine)
  • Relief of pain and inflammation associated with musculoskeletal disorders (e.g., lameness, myositis)
  • Reduction of fever (off-label)

Pharmacology & Mechanism of Action

Drug Class: Nonsteroidal Anti-inflammatory Drug (NSAID) | Pharmacological Group: Propionic acid derivative

Mechanism of Action: Carprofen is a nonsteroidal anti-inflammatory drug (NSAID) of the propionic acid class. It exerts its therapeutic effects primarily through inhibition of cyclooxygenase (COX) enzymes, thereby reducing the synthesis of prostaglandins from arachidonic acid. It has selective COX-2 inhibition in dogs, which contributes to its anti-inflammatory, analgesic, and antipyretic properties while sparing COX-1-mediated gastrointestinal and renal protective prostaglandins to a greater extent than non-selective NSAIDs. However, the selectivity is species-dependent and not absolute. Carprofen also has some inhibitory effect on neutrophil function and may have additional central analgesic actions.

Pharmacodynamics: Carprofen produces dose-dependent anti-inflammatory, analgesic, and antipyretic effects. In dogs, it reduces inflammation and pain associated with osteoarthritis and postoperative pain. Its analgesic potency is comparable to other NSAIDs, but it has a relatively long duration of action. It does not significantly affect platelet aggregation at therapeutic doses in dogs, which may be advantageous in surgical settings. In horses, it is used for musculoskeletal pain and inflammation, but its efficacy is less well-established compared to other NSAIDs like flunixin meglumine.

⚡ Pharmacokinetics Summary

Absorption: Carprofen is well absorbed after oral administration in dogs and cats. In dogs, peak plasma concentrations occur within 1-3 hours after oral dosing. Bioavailability is nearly complete after oral administration. In horses, oral absorption is slower and less complete, with bioavailability around 70-80%.
Distribution: Carprofen is highly protein-bound (>99%) in plasma, primarily to albumin. It distributes into synovial fluid, achieving concentrations that are approximately 50% of plasma levels. It has a small volume of distribution, indicating limited tissue penetration. It crosses the placenta and is excreted in milk.
Metabolism: Carprofen is extensively metabolized in the liver, primarily via oxidation and conjugation (glucuronidation). The major metabolic pathways involve hydroxylation of the aromatic ring and conjugation with glucuronic acid. In dogs, the primary metabolite is the glucuronide conjugate. There is enterohepatic recirculation, which may prolong its half-life.
Excretion: In dogs, carprofen is excreted primarily in the feces (approximately 70-80%) via biliary excretion, with the remainder excreted in urine. In cats, a larger proportion is excreted in urine. In horses, it is excreted mainly in urine as metabolites.
Half-Life: Dog: approximately 8 hours (range 4-12 hours); Cat: approximately 19 hours; Horse: approximately 20-30 hours; Cattle: approximately 30-40 hours (not approved for use in cattle).
Bioavailability: Oral: nearly 100% in dogs; approximately 70-80% in horses; not well established in cats but likely high.
Protein Binding: >99% in dogs and cats; approximately 99% in horses.

Available Formulations & Strengths

Oral Tablet 25 mg, 50 mg, 75 mg, 100 mg (Oral)
Oral Caplet 25 mg, 50 mg, 75 mg, 100 mg (Oral)
Injectable Solution 50 mg/mL (Subcutaneous or Intravenous)
Oral Paste (Horse) 100 mg/mL (Oral)
Oral Granules (Horse) 100 mg/g (Oral)

Contraindications & Clinical Warnings

Contraindications:
  • Known hypersensitivity to carprofen or other NSAIDs
  • Active gastrointestinal ulceration, bleeding, or perforation
  • Renal or hepatic impairment (severe)
  • Coagulopathies or bleeding disorders
  • Concurrent use of corticosteroids or other NSAIDs
  • Use in animals with cardiac disease (may cause fluid retention)
  • Use in pregnant or lactating animals (unless specifically indicated and risk-benefit assessed)
  • Use in food animals (cattle, sheep, goats, pigs, poultry) due to lack of withdrawal times and potential for toxicity
Warnings & Clinical Precautions:
  • Use with caution in animals with pre-existing renal, hepatic, or cardiac disease.
  • Monitor for signs of gastrointestinal toxicity (vomiting, diarrhea, melena, anorexia).
  • Use the lowest effective dose for the shortest duration.
  • In cats, use is off-label and requires extreme caution due to prolonged half-life and increased risk of toxicity.
  • In horses, do not use in animals intended for human consumption.
  • Avoid concurrent use with other NSAIDs or corticosteroids.
  • Administer with food to reduce gastrointestinal upset.
  • Monitor renal function in animals receiving long-term therapy.
  • In surgical patients, assess hemostasis before administration.
  • Do not exceed recommended dose or duration.
  • Keep out of reach of children and pets.

Adverse Effects & Reactions

Common:

  • Vomiting
  • Diarrhea
  • Decreased appetite
  • Lethargy
  • Increased thirst or urination

Serious / Severe:

  • Gastrointestinal ulceration, bleeding, or perforation
  • Renal toxicity (acute kidney injury)
  • Hepatotoxicity (elevated liver enzymes, jaundice)
  • Bone marrow suppression (rare)
  • Seizures (rare)

Rare:

  • Allergic reactions (skin rash, anaphylaxis)
  • Blood dyscrasias (thrombocytopenia, leukopenia)
  • Neurological signs (ataxia, tremors)

Key Drug Interactions

Interacting Drug / Class Clinical Effect & Mechanism Severity
Other NSAIDs (e.g., aspirin, meloxicam, flunixin) Additive risk of gastrointestinal ulceration, renal toxicity, and bleeding. High
Corticosteroids (e.g., prednisone, dexamethasone) Increased risk of gastrointestinal ulceration and perforation. High
Anticoagulants (e.g., warfarin, heparin) Increased risk of bleeding due to inhibition of platelet function. High
Diuretics (e.g., furosemide) Reduced diuretic efficacy and increased risk of renal toxicity due to decreased renal blood flow. Moderate
ACE inhibitors (e.g., enalapril) Reduced antihypertensive effect and increased risk of renal dysfunction. Moderate
Aminoglycoside antibiotics (e.g., gentamicin) Increased risk of nephrotoxicity. Moderate
Methotrexate Reduced renal excretion of methotrexate, leading to increased toxicity. Moderate

Overdose & Toxicity Management

Signs of Toxicity:

  • Vomiting
  • Diarrhea (possibly bloody)
  • Lethargy
  • Loss of appetite
  • Abdominal pain
  • Ataxia
  • Seizures
  • Coma
  • Renal failure (decreased urine output, elevated BUN/creatinine)
  • Hepatic failure (jaundice, elevated liver enzymes)

Emergency Treatment Protocol: Treatment is symptomatic and supportive. Induce emesis if ingestion is recent (within 2 hours) and the animal is conscious. Administer activated charcoal to reduce absorption. Provide intravenous fluids to maintain renal perfusion and correct dehydration. Monitor renal and hepatic function. Administer gastroprotectants (e.g., sucralfate, omeprazole) to reduce GI ulceration. In severe cases, consider hemodialysis or peritoneal dialysis. There is no specific antidote for carprofen overdose.

Food Animal Withdrawal Times

Carprofen is not approved for use in food animals. Therefore, no withdrawal times are established. Use in food animals is prohibited. In horses, carprofen is not approved for use in animals intended for human consumption; therefore, no withdrawal times are established. If used off-label in horses, a withdrawal time of at least 30 days for meat and 72 hours for milk is recommended, but this is not officially established.

Storage, Handling & Regulatory Information

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

Handling & Special Conditions: Protect from moisture. Keep in a tightly closed container. Do not freeze the injectable solution.

Dispensing Status: Prescription Required (Rx Only)

Approval Status: Approved for use in dogs (Rimadyl®) and horses (Rimadyl® equine). Not approved for use in cats or other species.

Extra-Label (Off-Label) Use: In the United States, carprofen is approved for use in dogs and horses. Extra-label use in other species (e.g., cats, rabbits) is permitted under the Animal Medicinal Drug Use Clarification Act (AMDUCA) if a valid veterinarian-client-patient relationship exists, and if the drug is not prohibited for use in food animals. However, extra-label use in food animals is prohibited if the drug is not approved for that species and no withdrawal times are established. In the European Union, similar regulations apply under the Cascade system.

Clinical Pearls & Practice Notes

💡 Clinical Insights: Carprofen is a widely used NSAID in veterinary medicine, primarily for pain and inflammation in dogs and horses. It is preferred in dogs due to its relatively high COX-2 selectivity, which reduces the risk of gastrointestinal and renal adverse effects compared to non-selective NSAIDs. However, it is not without risks, and long-term use should be accompanied by regular monitoring of liver and kidney function. In cats, carprofen is not approved and should be avoided due to its prolonged half-life and increased risk of toxicity; alternative NSAIDs such as meloxicam (with caution) or other analgesics are preferred. In horses, carprofen is less commonly used than flunixin meglumine or phenylbutazone, but it may be useful for chronic musculoskeletal pain. Always use the lowest effective dose for the shortest duration, and educate owners on the signs of adverse effects. Do not use in food animals due to lack of withdrawal times and potential for toxicity.

References & Literature

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