title: Pharmacokinetic of diclofenac in the presence and absence of glibenclamide in the rat.
abstract: OBJECTIVE
  There is evidence that the sulfonylurea antidiabetic agent glibenclamide reduces the analgesic action of non-steroidal anti-inflammatory drugs (NSAIDs), opioids and neuromodulators in animal models. Therefore, in view of the vast clinical uses and interactions of NSAIDs with commonly used therapeutic agents, the interaction of the NSAID diclofenac and glibenclamide was investigated about pharmacokinetic profile and antinociceptive effect in rats.
  
  
  METHODS
  Antinociception was assessed using the formalin test. Fifty microliters of diluted formalin was injected s.c. into the dorsal surface of the right hind paw. Nociceptive behavior was quantified as the number of flinches of the injected paw during 60 min after injection. Rats were treated with oral administration of vehicle or increasing doses of diclofenac (3-18 mg/kg) before formalin injection. To determine the pharmacodynamic interaction between diclofenac and glibenclamide, the effect of oral administration of glibenclamide (1-30 mg/kg) on the antinociceptive effect induced by diclofenac (18 mg/kg, p.o.) was assessed. To evaluate the pharmacokinetic interaction between diclofenac and glibenclamide, the effect of glibenclamide (10 mg/kg, p.o.) on the pharmacokinetic of diclofenac (18 mg/kg, p.o.) was studied in the rat. Blood samples were taken over 8 h and analyzed using a validated high-performance liquid chromatography method to generate the pharmacokinetic profile of diclofenac. Pharmacokinetic parameters were estimated using noncompartmental analysis.
  
  
  RESULTS
  Systemic administration of diclofenac produced a dose-dependent antinociceptive effect in the formalin test. Systemic treatment with glibenclamide prevented diclofenac-induced antinociception. In pharmacokinetic interaction study, no significant (P>0.05) change in diclofenac concentration-time profiles in the presence of glibenclamide was detected.
  
  
  CONCLUSIONS
  The experimental findings suggest that systemic glibenclamide is able to block the diclofenac-induced antinociception in the rat formalin test. Besides, this antagonism was not produced by diminution in the bioavailability of diclofenac. Likewise, the validated assay had sufficient accuracy and precision for pharmacokinetic determination of diclofenac in the rat.
authors.affiliation: Sección de Estudios de Postgrado e Investigación, Escuela Superior de Medicina, Instituto Politécnico Nacional, México, D.F., Mexico.
authors.forename: María R
authors.initials: MR
authors.lastname: León-Reyes
authors.forename: Gilberto
authors.initials: G
authors.lastname: Castañeda-Hernández
authors.forename: Mario I
authors.initials: MI
authors.lastname: Ortiz
mesh_terms: D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000037:antagonists & inhibitors / Q000097:blood / Q000493:pharmacokinetics* / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D004008:Diclofenac / Q000037:antagonists & inhibitors / Q000097:blood / Q000493:pharmacokinetics* / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D005260:Female; D005905:Glyburide / Q000008:administration & dosage / Q000494:pharmacology*; D007004:Hypoglycemic Agents / Q000008:administration & dosage / Q000494:pharmacology*; D054086:KATP Channels / Q000037:antagonists & inhibitors*; D057230:Limit of Detection; D010146:Pain / Q000188:drug therapy; D010147:Pain Measurement; D026902:Potassium Channel Blockers / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D007004:Hypoglycemic Agents; D054086:KATP Channels; D026902:Potassium Channel Blockers; D004008:Diclofenac; D005905:Glyburide