| Indication | For the treatment of rheumatoid arthritis, osteoarthritis, ankylosing spondylitis, tendinitis, bursitis, and acute gout. Also for the relief of mild to moderate pain and the treatment of primary dysmenorrhea. |
| Pharmacodynamics | Naproxen is a member of the arylacetic acid group of nonsteroidal anti-inflammatory drugs (NSAIDs). Naproxen has analgesic and antipyretic properties. As with other NSAIDs, its mode of action is not fully understood; however, its ability to inhibit prostaglandin synthesis may be involved in the anti-inflammatory effect. |
| Mechanism of action | The mechanism of action of naproxen, like that of other NSAIDs, is believed to be associated with the inhibition of cyclooxygenase activity. Two unique cyclooxygenases have been described in mammals. The constitutive cyclooxygenase, COX-1, synthesizes prostaglandins necessary for normal gastrointestinal and renal function. The inducible cyclooxygenase, COX-2, generates prostaglandins involved in inflammation. Inhibition of COX-1 is thought to be associated with gastrointestinal and renal toxicity while inhibition of COX-2 provides anti-inflammatory activity. |
| Absorption | Naproxen itself is rapidly and completely absorbed from the GI tract with an in vivo bioavailability of 95%. Although naproxen itself is well absorbed, the sodium salt form is more rapidly absorbed resulting in higher peak plasma levels for a given dose. Food causes a slight decrease in the rate absorption. |
| Volume of distribution | Not Available |
| Protein binding | At therapeutic levels naproxen is greater than 99% albumin-bound. |
| Metabolism | Naproxen is extensively metabolized to 6-0-desmethyl naproxen and both parent and metabolites do not induce metabolizing enzymes. |
| Route of elimination | Not Available |
| Half life | The observed terminal elimination half-life is approximately 15 hours. |
| Clearance | Not Available |
| Toxicity | ORAL (LD50): Acute: 248 mg/kg [Rat]. 360 mg/kg [Mouse]. Symptoms of overdose include drowsiness, heartburn, indigestion, nausea, and vomiting. |