title: Clonidine changes lidocaine free concentrations in rat myocardium without affecting heart function measured by echocardiography.
abstract: Lidocaine is a local anaesthetic widely used in regional and epidural anaesthesia. Clonidine a alpha2-adrenergic agonist is an antihypertensive agent, regulating the production of catecholamines (epinephrine and norepinephrine) and added to local anesthetic infusions in order to improve postoperative analgesia. The aim of the study was to investigate the influence of clonidine co-administration on the binding of 14C lidocaine to rat serum and heart tissue protein as well as its pharmacodynamic effects in the heart. Four groups of Wistar rats (n=7) were used; Groups I and II received 4 mg/kg lidocaine i.m. Groups III and IV received lidocaine and 1 microg/kg clonidine i.m. In group I and III fifteen minutes and in groups II and IV thirty minutes after the initial treatment, ultrasound examination of heart function (heart rate, diameter of left ventricle in systole and diastole, ejection fraction) was performed. The animals were then sacrificed in all groups. Lidocaine free fraction in serum and heart was evaluated via ultrafiltration. The kinetics of lidocaine was altered by clonidine co-administration probably by mechanisms related to protein binding alterations. However, the pharmacokinetic interactions were not accompanied by changes of pharmacodynamic parameters including those of heart function as measured by echocardiography.
authors.affiliation: Department of Pharmacology, Medical School, University of Athens, Athens, Hellas.
authors.forename: E
authors.initials: E
authors.lastname: Tigka
authors.forename: A
authors.initials: A
authors.lastname: Kotsiou
authors.forename: T
authors.initials: T
authors.lastname: Saranteas
authors.forename: J
authors.initials: J
authors.lastname: Mourouzis
authors.forename: G
authors.initials: G
authors.lastname: Kostopanagiotou
authors.forename: C
authors.initials: C
authors.lastname: Tesseromatis
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000779:Anesthetics, Local / Q000493:pharmacokinetics*; D000818:Animals; D003000:Clonidine / Q000494:pharmacology*; D004347:Drug Interactions; D004452:Echocardiography; D006339:Heart Rate / Q000187:drug effects; D007273:Injections, Intramuscular; D008012:Lidocaine / Q000493:pharmacokinetics*; D009206:Myocardium / Q000378:metabolism; D011485:Protein Binding; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors
chemical_list: D000316:Adrenergic alpha-Agonists; D000779:Anesthetics, Local; D008012:Lidocaine; D003000:Clonidine