Naproxen:

• It is a propionic acid derivative NSAID; insoluble in water and freely soluble in alcohol.
• Non-selective NSAID and mediates its action through inhibition of PG synthesis. It also inhibits leucocytes migration.

Pharmacological Effects:

• It exhibits analgesic, anti-inflammatory and anti-pyretic activities like other NSAID

Pharmacokinetics:

• Bioavailability after oral administration is 50% in horses, and 70-100% in dogs
• It is highly bound to plasma protein
• Elimination half-life is:
  • Horse: 20 hr
  • Cattle: 13 hr
  • Dogs: 35-74 hr
  • Man: 20 hr

Side effects/Adverse effects:

• It has relatively wide margin of safety
• Occasionally, GI disturbances, renal and hematological effects occur in horses.
• It is toxic to dogs; GI ulcers, nephritis, hepatitis

Drug Interactions:

• It should not be used along with other nephrotoxic drugs
• Concurrent use of aspirin or other potent NSAID may enhance ulcerogenic effect of naproxen.
• Corticosteroids exacerbate the GI adverse effects.

Contraindications and precautions:

• Contraindicated in dog with bleeding disorders, GI ulcers or cardiac or hepatic disease.
• In patients with hypersensitive to it.
• It should be used with caution in older, young and pregnant animals.

Indications:

• Pain and lameness due to Musculo-skeletal system
• Osteoarthritis in dogs
• Pain, fever, inflammation and stiffness in human
• In disease like osteoarthritis, rheumatoid arthritis, gout, ankylosing spondylitis, menstrual cramp, tendinitis and bursitis.

Dose:

• Horse: 10 mg/kg, PO, BID x 14 days

 5 mg/kg, slow IV followed by 10 mg/kg, PO, BID x 14 days

• Dogs: 5 mg/kg, PO and then 2 mg/kg on alternate days