title: Isobolographic analysis of the antinociceptive interactions of clonidine with nonsteroidal anti-inflammatory drugs.
abstract: The present study was undertaken to characterize the interactions between nonsteroidal anti-inflammatory drugs and the alpha(2)-adrenoceptor agonist clonidine in an acute nociceptive test. The writhing test was selected as a model of acute visceral pain. Isobolograms were constructed to assess the interactions of clonidine and each nonsteroidal anti-inflammatory drugs, when coadministered intraperitoneally and intrathecally (i.t.). The simultaneous intraperitoneal administration of fixed ratios of ED(50) fractions of all nonsteroidal anti-inflammatory drugs (naproxen, piroxicam, paracetamol, dipyrone or metamizol and nimesulide) combined with clonidine resulted in synergistic interactions. The same combinations administered intrathecally were additive. The synergistic interactions between systemic nonsteroidal anti-inflammatory drugs and clonidine may involve supraspinal mechanisms.
authors.affiliation: Pharmacology Program, ICBM, Faculty of Medicine, University of Chile, P.O. Box 70,000, Santiago 7, Chile. hmiranda@machi.med.uchile.cl
authors.forename: H F
authors.initials: HF
authors.lastname: Miranda
authors.forename: G
authors.initials: G
authors.lastname: Pinardi
mesh_terms: D000700:Analgesics / Q000493:pharmacokinetics / Q000494:pharmacology*; D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000493:pharmacokinetics / Q000494:pharmacology*; D003000:Clonidine / Q000493:pharmacokinetics / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions / Q000502:physiology; D004359:Drug Therapy, Combination; D005260:Female; D007274:Injections, Intraperitoneal; D007278:Injections, Spinal; D008297:Male; D051379:Mice; D010147:Pain Measurement / Q000187:drug effects* / Q000379:methods
chemical_list: D000700:Analgesics; D000894:Anti-Inflammatory Agents, Non-Steroidal; D003000:Clonidine