Mavacoxib
Mavacoxib is a highly unique, ultra-long-acting non-steroidal anti-inflammatory drug (NSAID) of the coxib class. Unlike traditional daily NSAIDs, mavacoxib is designed for monthly administration, making it an excellent choice for patients whose owners struggle with daily dosing compliance. **Clinical Pearl:** Because of its exceptionally long half-life (averaging 16-17 days), any adverse effects may persist for weeks after the drug is discontinued. Therefore, careful patient selection is critical, and it is generally reserved for chronic osteoarthritis management rather than acute pain.
Mechanism: Mavacoxib is a **COX-2 selective inhibitor** (coxib). * **Arachidonic Acid Cascade:** It selectively inhibits the **cyclooxygenase-2 (COX-2)** enzyme → decreases the production of pro-inflammatory prostaglandins (such as PGE2) → reduces pain, inflammation, and fever. * **COX-1 Sparing:** At therapeutic dosages, it relatively spares **COX-1**, the constitutive enzyme responsible for synthesizing prostaglandins that protect the gastric mucosa, support platelet function, and maintain normal renal blood flow. However, COX-selectivity is relative and can be lost at higher doses or in susceptible individuals.
Dosing by species
- Any · Do not use · PO · N/A · N/A · Contraindicated in cats.
- Pain and inflammation associated with degenerative joint disease in dogs aged 12 months or more in cases where continuous treatment exceeding one month is indicated · 2 mg/kg PO given immediately before or with the dog's main meal. The treatment should be repeated 14 days later; thereafter the dosing interval is one month. · PO · Day 1, Day 14, then monthly · A treatment cycle should not exceed 7 consecutive doses (6.5 months). · Care should be taken to ensure that the tablet is ingested. THIS IS not a daily NSAID.
- Pain and inflammation associated with degenerative joint disease (osteoarthritis) · 2 mg/kg · PO · q14d for 2 doses, then q1month · Maximum of 7 doses total · Should be given immediately before or with the dog's main meal. Treatment can potentially be re-started after a 1-month break from dosing.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Routes of administration
Contraindications
- Dogs less than 12 months of age
- Dogs less than 5 kg body weight
- Gastrointestinal disorders including ulceration and bleeding
- Evidence of a hemorrhagic disorder
- Impaired renal or hepatic function
- Cardiac insufficiency
- Hypersensitivity to mavacoxib, sulfonamides, or excipients
- Pregnant, breeding, or lactating animals
- Dehydrated, hypovolemic, or hypotensive animals
- Dehydrated, hypovolaemic, or hypotensive patients
- Gastrointestinal disease or ulceration
- Blood clotting disorders
- Liver disease (prolongs metabolism and causes accumulation)
- Renal disease (requires careful evaluation, generally avoid)
- Pregnant or lactating animals
Adverse effects
- Inappetence
- Diarrhea
- Vomiting
- Depression
- Renal toxicity
- Gastrointestinal ulceration
- Gastrointestinal ulceration or bleeding
- Vomiting and diarrhoea
- Renal toxicity (especially if dehydrated or hypotensive)
- Hepatic accumulation (in poor metabolizers)
- Theoretical risk of precipitating cardiac failure
Drug interactions
- ACE Inhibitors (e.g., enalapril, benazepril) · NSAIDs can reduce effects on blood pressure and potentially reduce renal blood flow, increasing the risk for renal injury.
- Aspirin · May increase the risk of gastrointestinal toxicity (ulceration, bleeding, vomiting, diarrhea). Long washout periods are warranted when switching.
- Corticosteroids (e.g., prednisone) · May increase the risk of gastrointestinal toxicity (ulceration, bleeding, vomiting, diarrhea). Concurrent use is contraindicated.
- Digoxin · NSAIDs may increase serum levels of digoxin.
- Fluconazole · May increase plasma levels of mavacoxib (extrapolated from celecoxib data in humans).
- Furosemide · NSAIDs may reduce saluretic and diuretic effects.
- Methotrexate · Serious toxicity has occurred when NSAIDs have been used concomitantly; use together with extreme caution.
- Nephrotoxic Drugs (e.g., aminoglycosides, amphotericin B) · May enhance the risk of nephrotoxicity development.
- Other NSAIDs · May increase the risk of gastrointestinal toxicity. Do not administer other NSAIDs within 1 month of the last administration of mavacoxib. · major
- Glucocorticoids · Increased risk of severe gastrointestinal ulceration and bleeding. · major
- Aminoglycosides · Increased risk of nephrotoxicity. · major
Monitoring
- Baseline and periodic CBC and serum chemistry (including BUN/serum creatinine, and liver function assessment)
- Baseline history and physical
- Efficacy of therapy
- Adverse effect monitoring via client
- Baseline and periodic renal function (BUN, Creatinine, SDMA, USG)
- Baseline and periodic hepatic function (ALT, ALP, Bilirubin)
- Clinical signs of GI ulceration (vomiting, melaena, anorexia)
- Hydration status and blood pressure (especially during anaesthesia)
Overdose
In safety studies, repeated doses of 5 and 10 mg/kg did not demonstrate adverse events. At **15 mg/kg**, vomiting, softened/mucoid feces, and decreased renal function were noted. Doses of **25 mg/kg** caused GI ulceration, with one fatality from GI perforation and peritonitis. * **Management:** Manage as with other NSAID toxicity (emetics, activated charcoal, GI protectants, fluid diuresis). * **Important:** Because of the drug's very long duration of effect, prolonged monitoring and treatment may be required. Consulting a veterinary poison center is highly recommended.
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.