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Mu-Opioid Receptor Genetic Polymorphism and Intrathecal Analgesia

NCT00418015 · Status: COMPLETED · Type: OBSERVATIONAL · Enrollment: 293

Last updated 2014-04-14

Study results available
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Summary

Pharmacogenetics has allowed clinicians to identify associations between an individual's genetic profile and his/her response to drugs. The A118G (c.188A\>G)is a single nucleotide polymorphism (SNP) of the mu-opioid receptor (OPRM1). The mutated protein, N40D, appears to increase the binding affinity and potency of beta-endorphin approximately 3-fold. Individuals carrying the variant receptor gene (A118G) may show differences in some of the functions mediated by beta-endorphin action at the altered OPRM1. Combined spinal-epidural (CSE) analgesia is a commonly utilized technique for labor analgesia. Analgesia is initiated with the intrathecal administration of a lipid-soluble opioid (e.g. fentanyl), sometimes combined with a local anesthetic. The mean (± SD) duration of analgesia after intrathecal fentanyl 25 microgram was 89 ± 43 min. The ED50 of intrathecal fentanyl for labor analgesia varies between 14 microgram to 18.2 microgram. The wide variability in the duration of analgesia, as was well the differences in ED50 may result from differences known to affect labor pain (e.g., ethnicity, parity, stage of labor). Another possible explanation for the differences in opioid requirements and duration, as well as incidence of side effects such as itching and nausea/vomiting, is that opioid responsiveness is determined by genetic variability of the µ-opioid receptor. The ED50 for intrathecal fentanyl labor analgesia was significantly lower for parturients carrying the A118G variant of the mu-opioid receptor, compared to parturients with the A118 wild type receptor. The purpose of this study is to determine whether polymorphism at nucleotide 118 of OPRM1 influences the duration of intrathecal opioid (fentanyl) labor analgesia, and intrathecal opioid (morphine) postoperative analgesia.

Conditions

  • Labor Pain
  • Post-cesarean Delivery

Interventions

PROCEDURE

Blood Draw

Blood for OPRM1 analysis

Sponsors & Collaborators

Principal Investigators

  • Cynthia A Wong, M.D. · Northwestern University

Eligibility

Min Age
18 Years
Max Age
55 Years
Sex
FEMALE
Healthy Volunteers
Yes

Timeline & Regulatory

Start
2005-10-31
Primary Completion
2007-05-31
Completion
2007-06-30

Countries

  • United States

Study Locations

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Read the full study record

This page highlights key information. For complete eligibility criteria, study locations, investigator contacts, and the full protocol, visit the original record on ClinicalTrials.gov.

View NCT00418015 on ClinicalTrials.gov