DETERMINATION OF DICLOFENAC SODIUM IN RABBIT PLASMA BY HPLC/UV: EVALUATION AND CHARACTERIZATION OF ITS CRYSTALLINE FORMS, ANHYDROUS AND HYDRATE, ON THE ANTIPYRETIC EFFECT

Abstract

Diclofenac sodium (DS) is a non-steroidal anti-inflammatory drug that is widely prescribed for the treatment of rheumatoid arthritis and post-surgery analgesia. The active pharmaceutical ingredient is the anhydrous form; however, it can also exist in hydrate form. In this context, knowing the properties of the solid state is important and relevant in the pharmaceutical area because they have a significant impact on the solubility, bioavailability, and chemical stability of the drugs. In the present study, data from XRPD, FTIR spectroscopy, and thermal analysis were used for the identification and characterization of DS forms (anhydrous and hydrate). An HPLC method was optimized to evaluate the plasma concentration of DS in rabbits. The optimized method exhibited good linearity over the range 0.1–60 µg/mL with correlation coefficients of >0.9991. The mean recovery was 100%. Precision and accuracy were determined within acceptable limits. Finally, to compare the pharmacological properties of anhydrous and hydrate DS forms, we investigated their effects in the febrile response induced by lipopolysaccharide from E. coli in rabbits. The results show that the antipyretic effect of anhydrous and hydrate DS forms are similar.

Keywords:

• diclofenac sodium
• fever
• HPLC
• polymorphism
• rabbit
• validation

ACKNOWLEDGMENT

The authors gratefully acknowledge the assistance and original work of Dra. Valquíria A. P. Jabor in the LC-MS/MS experiments, the assistance of Paulo S. Carvalho in the TGA and DSC experiments, the assistance of Míriam C. C. de Melo in the in vivo experiments, and the assistance of Profª Drª Vera L. Lanchotte in the analyses of pharmacokinetic data. Additionally, the authors acknowledge CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico) for granting research fellowships. Silvia L. Cuffini would like to thank CONICET, Fundación Sauberam and MinCyT-Córdoba.

Notes

^a CV, coefficient of variation.

Conc., concentration; CV, coefficient of variation; n, number of determinations.

^a Student's t-test with 95% confidence interval (p < 0.05).