Kinetics of the radicals induced in gamma-irradiated naproxen sodium and apranax. Applicability of ESR technique to monitor radiosterilization of naproxen sodium-containing drugs

Int J Pharm. 2002 Sep 5;244(1-2):169-79. doi: 10.1016/s0378-5173(02)00329-0.


In the present work the spectroscopic and kinetic features of the radicals induced in gamma-irradiated naproxen sodium (NS) and apranax (AP) tablet are investigated at room and different temperatures in the dose range of 2.5-25 kGy by electron spin resonance technique (ESR). Radiation produces two different radicals (I, II) in NS quite stable at room temperature but relatively unstable above room temperature, giving rise to a broad singlet centered at g = 2.0057. Dose-response and decay curves associated with the broad singlet were found to follow bi-exponentials. Information concerning the saturation decay rates and activation energies were obtained through the characteristics of these exponentials. Similar calculations were also performed for AP, which contains 550 mg NS as active ingredient, and the applicability of ESR technique for monitoring radiosterilization of AP was discussed.

MeSH terms

  • Anti-Inflammatory Agents, Non-Steroidal / radiation effects*
  • Dose-Response Relationship, Radiation
  • Electron Spin Resonance Spectroscopy / methods*
  • Gamma Rays*
  • Kinetics
  • Naproxen / radiation effects*


  • Anti-Inflammatory Agents, Non-Steroidal
  • Naproxen