Pharmacogenetic and Duration of Labor Fentanyl Analgesia Clinical Trial
Official title:
Observational Study: The Effect of μ-opioid Receptor Genetic Polymorphism on Neuraxial Opioid Labor Analgesia
In this prospective observational double-blind study, the investigators aim to assess the effect of the single nucleotide polymorphism of the μ-opioid receptor gene (OPRM1, p.118A/G) on the duration of epidural fentanyl labor analgesia.
The single nucleotide polymorphism (SNP), p.118A/G of the µ -opioid receptor gene (OPRM1),
may alter pain perception and individual response to opioid analgesia. This SNP leads to a
variant µ-opioid receptor in which an asparagine is substituted for aspartate as the 102nd
amino acid of the receptor protein (p.Asn102Asp). At the investigators' institution, it is
common practice to initiate labor analgesia with epidural fentanyl. No data are available to
determine how the µ-opioid polymorphism affects pain perception and response to opioids, such
as fentanyl, in the investigators' population. The investigators aim to assess the effect of
the single nucleotide polymorphism of the µ-opioid receptor gene (OPRM1, p.118A/G) on
duration of epidural fentanyl labor analgesia.
This is a prospective observational and double-blind study. Before initiation of epidural
labor analgesia, venous blood will be drawn into coded EDTA tubes. DNA isolation and
genotyping of OPRM1:p.118A/G will be performed at the American University of Beirut. In 250
parturients, labor epidural analgesia will be initiated with 100 µg of epidural fentanyl
following a test dose of lidocaine and epinephrine. No drugs will be injected until second
request of analgesia. Patients will be divided into two groups based on their genetic groups:
Group A consists of wild-type homozygote (A118), and Group G includes heterozygote and
homozygote carrying the G118 allele. Duration of fentanyl analgesia (primary outcome) will be
compared. Data will be presented as a mean ± SD or numbers and percentages. Statistical
analysis will be performed with the Student's t-test, Chi-square or Fisher's exact test as
appropriate. P value <0.05 will be considered significant.
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