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Effect of clonidine, nimodipine and diltiazem on the in vitro opioid withdrawal response in the guinea‐pig ileum
Author(s) -
Alfaro M.J.,
Colado M.I.,
López F.,
Martín M.I.
Publication year - 1990
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1990.tb14187.x
Subject(s) - nimodipine , diltiazem , clonidine , (+) naloxone , ileum , morphine , pharmacology , chemistry , anesthesia , medicine , endocrinology , opioid , calcium , receptor
1 The effects of clonidine, nimodipine and diltiazem, on the in vitro withdrawal contracture induced by naloxone in the guinea‐pig ileum obtained from morphine‐dependent animals, were evaluated. 2 The in vitro incubation with clonidine (0.01, 0.1 and 1 μ m ), diltiazem (0.25, 0.5 and 1 μ m ) or nimodipine (0.05, 0.1 and 1 μ m ) reduced significantly the force of the contracture induced by naloxone in the morphine‐dependent guinea‐pig ileum. 3 The intraperitoneal administration of clonidine (0.3 mg kg −1 ), nimodipine (5 mg kg −1 ) or diltiazem (20 mg kg −1 ) reduced the contractile response induced by naloxone in the morphine‐dependent guinea‐pig ileum. 4 It is concluded that at least part of the effect of clonidine, nimodipine and diltiazem on withdrawal contractures is mediated via a peripheral, rather than a central site of action. Even though, the mechanism responsible for the effect of the calcium channel blockers differs from that of α 2 ‐adrenoceptor agonists, all of the drugs tested prevented the contracture induced by naloxone in morphine‐dependent guinea‐pig ileum.