Bioavailability of naproxen sodium and its relationship to clinical analgesic effects.

1 In the first of a series of trials with naproxen sodium it was shown that patients achieved significantly earlier and higher plasma levels of naproxen when naproxen sodium was administered. 2 In a second study comparing naproxen with naproxen sodium in patients with post-partum pain, pain intensity was consistently lower for the group receiving naproxen sodium. However, statistically significant differences were not seen until 4 to 5 h after medication. 3 A final study documented that a more frequent dosage schedule of every 6 h led to clearly higher plasma levels than those achieved with an every 8 h regimen; plasma levels did not plateau. Doses up to 1,375 mg/day were well tolerated. 4 In conclusion, naproxen sodium appears to be an improved form of naproxen for use as a analgesic agent.