Synthesis, biological evaluation and kinetic studies of glyceride prodrugs of diclofenac

Abstract

The prodrugs (glyceride derivat ives) <b>3a</b> and <b>3b</b> of diclofenac were prepared by reacting 1,2, 3-trihydroxy propane-1 ,3-dipalmitate/stearate with the acid chloride of diclofenac as potenti al prodrugs to reduce the gastrointestinal toxicity associated with them. These prodrugs were evaluated for their ulcerogenicity, anti-inflammatory and analgesic activity. It was found that the prodrugs were significantly less irritating to the gastric mucosa as indicated by severity index of 0.86, 0.78 compared to 1.6 of diclofenac. The prod rugs <b>3a</b> and <b>3b</b> showed better anti-inflammatory and analgesic activity than the parent drugs. The hydrolysis of prodrugs <b>3a</b> and <b>3b</b> were studied at <i>p</i>H 3, 4, 5 and 7.4. The HPLC analysis showed that the prodrugs were resistant to hydrolysis at <i>p</i>H 3, 4 and 5 indicating that they did not hydrolyze in acidic environment, whereas at <i>p</i>H 7.4 the prodrugs readily released the parent drug in significant quantities. The plasma levels of diclofenac were also analyzed by HPLC in rats after single oral dose of the prodrugs. The results indicated that the parent drugs were readily released. The concentration of diclofenac during the study was found higher in animals treated with prodrugs <b>3a</b> and <b>3b</b> compared with animals treated with diclofenac. The concentration of diclofenac was found to be 38.59, 33.6 and 30.36 μg/ml in animals treated with prodrugs <b>3a,</b> <b>3b</b> and diclofenac respectively. In conclusion, all these studies indicated that the glyceride prodrugs of diclofenac might be considered as potential biolabile prodrugs of diclofenac.