Skelan Mechanism of Action

Pharmacology: Pharmacodynamics: Naproxen Sodium is a non-steroidal anti-inflammatory drug (NSAID) that exhibits anti-inflammatory, analgesic and antipyretic activity by inhibiting cyclooxygenase (COX)-1 and COX-2 isoenzymes resulting in inhibition of prostaglandin synthesis.
Pain relief with Naproxen Sodium usually begins within 30 minutes compared with 1 hour for plain Naproxen.
Pharmacokinetics: Naproxen and Naproxen Sodium are readily absorbed from the gastrointestinal tract with Naproxen Sodium dissolving more rapidly in gastric juice than plain Naproxen. Thus, Naproxen Sodium is more rapidly absorbed with peak plasma concentrations occurring about 1 to 2 hours after oral administration compared with 2 to 4 hours for naproxen. Naproxen Sodium's oral bioavailability is 95%. The rate but not the extent of absorption is decreased when Naproxen or Naproxen Sodium is taken with food.
Naproxen has a volume of distribution of 0.16 L/kg and is more than 99% plasma protein bound. Naproxen plasma concentrations increase proportionately with doses up to 500 mg daily. Increased clearance due to saturation of plasma proteins is seen at higher doses. Naproxen diffuses into synovial fluid, crosses the placenta and is also distributed in small amounts into breast milk. Naproxen's plasma half-life is about 13 hours.
Naproxen is extensively metabolized in the liver with about 95% of a dose excreted in the urine as Naproxen and 6-desmethylnaproxen and their conjugates and less than 5% of a dose is excreted in the feces.