CompletedNot Applicable

Mu-Opioid Receptor Genetic Polymorphism and Intrathecal Analgesia

United States293 participantsStarted 2005-10

Plain-language 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.

Who can participate

Age range

18 Years – 55 Years

Sex

FEMALE

See this in plain English?

AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.

Inclusion Criteria: Study 1: Laboring Women * Nulliparous women in spontaneous labor or with spontaneous rupture of membranes * Term pregnancy (≥ 37 weeks gestation) * Vertex presentation * Healthy, ASA PS 1-2 * Desire neuraxial labor analgesia. Study 2: Cesarean Delivery * Nulliparous women undergoing elective primary Cesarean delivery (e.g., for breech presentation, macrosomia) * Term pregnancy (≥ 37 weeks gestation) * Healthy, ASA PS 1-2 * Desired spinal anesthesia. Exclusion Criteria: Study 1: Laboring Women * Chronic or pregnancy induced disease * Chronic opioid use * History of substance abuse * Systemic opioid analgesia before initiation of neuraxial labor analgesia * Cervical dilation \< 2 cm or \> 5 cm of time of request for neuraxial analgesia * Allergy to fentanyl Study 2: Cesarean delivery * Chronic or pregnancy induced disease * Chronic opioid use * Previous abdominal or pelvic surgery * Allergy to fentanyl, morphine, or bupivacaine * BMI ≥ 40 kg/m2 * History of substance abuse * Failed spinal anesthesia * Requirement for systemic opioid supplementation during Cesarean delivery.

Questions worth asking your doctor

Bring these to your next appointment. They're a starting point for a shared conversation — not a sign you qualify or a recommendation to enrol.

1Based on my diagnosis and history, is this trial worth exploring for me — or is there a standard treatment we should try first?
2What does this trial's phase tell us about how much is already known about its safety and benefit?
3What would taking part actually involve for me — visits, tests, time, and travel?
4What are the known and possible risks or side effects I should weigh, and how would they be monitored?
5If this trial isn't the right fit, what other options or trials would you suggest I look into?

Generated to help you prepare — always confirm anything about your own eligibility and care with the study team and your doctor.

Questions for the trial coordinator

The trial coordinator is the person who runs the study day to day. These cover the practical side — logistics, costs, and what taking part would actually mean for your life. The study team confirms whether you meet the criteria; these are questions to ask, not a sign you qualify.

1What does taking part actually involve week to week — how many visits, where, and how long does each one take?
2What costs are covered by the study, and what might I have to pay for myself, including travel, parking, or time off work?
3What happens during screening, and what happens if the study team confirms I don't meet the criteria after those tests?
4Who pays for the scans, blood work, and other tests the trial requires — the study, my insurance, or me?
5How will being in the trial affect my regular care, and will my own doctor stay informed and involved?
6Can I leave the trial at any point if I change my mind, and what would happen to my care if I do?

A starting point for the conversation — always confirm anything about your own eligibility, costs, and care with the study team and your doctor.

What they're measuring

Duration of Intrathecal Fentanyl Analgesia

Timeframe: Time (0-1440 minutes) to first analgesia request

Duration of Intrathecal Analgesia Following Cesarean Delivery

Timeframe: 0 to 72 hours following cesarean delivery

Visual Analog Pain Scale (0 to 100) at Analgesia Request Following Intrathecal Intervention

Timeframe: VAS at analgesia request

Trial details

NCT IDNCT00418015

SponsorNorthwestern University

Sponsor typeOTHER

Study typeOBSERVATIONAL

Primary completion2007-05

Results submitted2011-02-15

View on ClinicalTrials.gov More Labor Pain trials