JOURNAL HOME CME HOME THIS MONTH PAST ISSUES ETOC COLLECTIONS AUTHORS REVIEWERS EDITORIAL BOARD FEEDBACK RSS HELP
		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a colleague Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Jamous, M. A. Articles by McQuay, H. J. Search for Related Content PubMed PubMed Citation Articles by Jamous, M. A. Articles by McQuay, H. J.

Epinephrine Reduces Systemic Absorption of Extradural Diacetylmorphine

Received from the Department of Neurosurgery and the Nuffield Departments of Clinical Biochemistry and Anaesthetics, Radcliffe Infirmary, Oxford, England.

Abstract

The effect of epinephrine on the vascular absorption of morphine from the extradural space is uncertain; this study examined the effect of epinephrine on the related but more lipophilic opiate diacetylmorphine (diamorphine, heroin) because any effects of vasoconstriction on diacetylmorphine absorption should be maximally apparent. With this experiment, we hoped to resolve whether epinephrine does or does not alter vascular absorption of extradurally injected opiates. Thirty patients undergoing lumbar laminectomy were given either extradural diacetylmorphine, 5 mg, extradural diacetylmorphine, 5 mg with 1:200,000 epinephrine, or 1:200,000 epinephrine followed 5 min later by 5 mg extradural diacetylmorphine. Plasma morphine concentrations were measured by radioimmunoassay because of the rapid conversion of diacetylmorphine to morphine in plasma; repeated blood samples were obtained the first 30 min after injection into the epidural space. Significantly lower plasma morphine levels occurred between 3 and 20 min when epinephrine was added to diacetylmorphine. Peak plasma morphine levels (mean ± SEM) were 179 ± 37 nmol/L with diacetylmorphine alone, 87 ± 16 nmol/L with diacetylmorphine and epinephrine given together and 44 ± 11 nmoll L with epinephrine pretreatment, all significantly different from one another. The mean peak plasma morphine concentration was 8.7 ± 1.1 min for diacetylmorphine alone, but addition of epinephrine (together or sequentially) meant that 15 of 20 patients had no peak level before 120 min. Epinephrine reduced absorption of diacetylmorphine from the extradural site by at least 55% over the first 30 min. The incidence of patients with more than 9 hr analgesic duration was significantly (P = 0.033) greater in patients who had diacetylmorphine and epinephrine. The use of diacetylmorphine as a model for lipophilic opiates showed that addition of epinephrine not only reduced systemic absorption but also increased analgesic duration. The addition of epinephrine to similarly lipophilic opiates should have the same clinically desirable consequence.

Key Words: ANALGESICS—diacetylmorphine (heroin). • PAIN—postoperative. ANESTHETIC TECHNIQUES—epidural.

Anesthesia & Analgesia® is published for the International Anesthesia Research Society® by Lippincott Williams & Wilkins with the assistance of Stanford University Libraries' HighWire Press®. Copyright 2006 by the International Anesthesia Research Society. Online ISSN: 1526-7598   Print ISSN: 0003-2999