Carprofen

BRAND NAMES

Common brand names for carprofen include:

• Rimadyl – widely used veterinary NSAID

• Novox – often a generic chewable form

• Vetprofen – another generic veterinary option

MECHANISM OF ACTION

Carprofen works by blocking COX enzymes, which reduces prostaglandins that cause pain and inflammation, helping relieve arthritis or post-surgery discomfort in dogs.

PHARMACOKINETICS

Absorption

Carprofen is well absorbed orally in dogs, with peak blood levels typically reached 1–3 hours after administration. Food can slightly slow absorption but does not significantly reduce its effectiveness.

Distribution

Carprofen has a volume of distribution (Vd) of approximately 0.14–0.28 L/kg in dogs, indicating it is mainly distributed in the blood and extracellular fluids rather than extensively into tissues.

Metabolism 

Carprofen is primarily metabolized in the liver in dogs through enzymatic oxidation and conjugation, producing inactive metabolites that are easier for the body to excrete.

Excretion

Carprofen is mainly excreted in the bile via the feces, with a smaller amount eliminated through the urine. Most of the drug and its metabolites are cleared within 24 hours in dogs.

PHARMACODYNAMICS

 Carprofen’s pharmacodynamics involve inhibition of COX-1 and COX-2 enzymes, which reduces the production of prostaglandins responsible for pain, inflammation, and fever. This leads to analgesic, anti-inflammatory, and antipyretic effects, particularly useful for managing osteoarthritis and post-operative pain in dogs.

ADMINISTRATION

Carprofen is administered orally in dogs, usually as tablets or chewable tablets. It is typically given once or twice daily with or without food, as prescribed by a veterinarian.

DOSAGE AND STRENGTH

The typical dosage of carprofen for dogs is 2 mg/kg to 4 mg/kg once or twice daily, depending on the condition and veterinary guidance.

Common strengths of tablets include:

• 25 mg

• 75 mg

• 100 mg

FOOD INTERACTIONS

Carprofen can be given with or without food. Giving it with food may slightly slow absorption but can help reduce the risk of gastrointestinal upset, such as vomiting or stomach irritation, which is the main food-related consideration.

DRUG INTERACTIONS

• Other NSAIDs (e.g., aspirin, meloxicam) – increased risk of gastrointestinal bleeding

• Corticosteroids (e.g., prednisone) – higher risk of stomach ulcers

• Diuretics – may reduce kidney function

• ACE inhibitors or angiotensin receptor blockers – possible kidney effects

• Anticoagulants – may increase bleeding risk

CONTRAINDICATIONS

• Known hypersensitivity to carprofen or other NSAIDs

• Active gastrointestinal ulcers or bleeding

• Severe kidney or liver disease

• Pregnancy or lactation (unless specifically prescribed by a vet)

• Dehydration or hypovolemia, which increases risk of kidney injury

SIDE EFFECTS

• Gastrointestinal issues: vomiting, diarrhea, decreased appetite

• Lethargy or reduced activity

• Liver effects: elevated liver enzymes (rare)

• Kidney effects: changes in urination or kidney function (rare)

• Allergic reactions: swelling, itching, or hives (rare)

OVERDOSE

• Severe vomiting or diarrhea

• Loss of appetite

• Lethargy or weakness

• Blood in vomit or stool (gastrointestinal bleeding)

• Kidney or liver damage

TOXICITY

Carprofen toxicity can occur with overdose or prolonged use, primarily affecting the stomach, kidneys, and liver. Signs include vomiting, diarrhea, lethargy, and decreased urine output, and severe cases may cause organ damage. Immediate veterinary care is essential.