Naproxen Twice Daily Versus as Needed (PRN) Dosing: Efficacy and Tolerability for Treatment of Acute Ankle Sprain, a Randomized Clinical Trial

This study was conducted to compare the efficacy and safety of naproxen 500 mg twice daily (BID) versus naproxen 500 mg as needed (PRN) for treatment of ankle sprain. In this seven-day, randomized, parallel group trial, 135 patients with ankle sprain occurring less than 48 hours prior to the first dose of study medication were randomized to receive naproxen 500 mg BID (67 patients) and naproxen 500 mg as needed (PRN) (68 patients). The ankle pain was assessed at rest and on full weight bearing using Numeric Rating Scale (NRS) from 0 (no pain) to 10 (the worst imaginable pain). Ankle swelling was assessed as a 4-point scale ranging from 0 (no swelling) to 3 (severe swelling) rated by the investigator. The primary efficacy end point was the patient’s assessment of ankle pain via NRS and the degree of swelling on day seven. Results showed a significant decrease in pain on weight bearing, pain at rest and the extent of swelling (P<0.001) in both groups, but there was no substantial difference between the two groups (P>0.05) after seven days. Assessing the safety profile of the two different dosing, 13.3 % of the naproxen BID group and 6.7 % of the as needed group had adverse events, showing that the as needed regimen was safer (P<0.001). Results showed that naproxen as needed may reduce the pain and edema of the sprained ankle with no significant difference compared to the BID regimen, while it possesses better safety profile and lower total drug use.