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Influence of OPRM1 Polymorphism on Post-operative Pain After Intrathecal Morphine Administration in Italian Patients Undergoing Elective Cesarean Section

Pettini, Eleonora MD; Micaglio, Massimo MD; Bitossi, Ubaldo MD; De Gaudio, Angelo Raffaele MD; Degl’Innocenti, Duccio Rossi MD; Tofani, Lorenzo PhD; Limatola, Vittorio MD; Adembri, Chiara MD; Di Filippo, Alessandro MD
The Clinical Journal of Pain: Post Acceptance: June 06, 2017
doi: 10.1097/AJP.0000000000000520
Original Article: PDF Only


the aim of this prospective observational study was to evaluate the influence of OPRM1 polymorphism on the analgesic efficacy (including VAS scores and requirement for rescue analgesia) of a standard dose of intrathecal morphine


an Italian cohort of 63 parturients, scheduled for elective cesarean section at a tertiary University Hospital, received a spinal anesthesia with hyperbaric bupivacaine and morphine 100 mcg. For the first 48 hours in the post-operative period the patients received acetaminophen 1 g IV q6hr. Incident pain was treated with ketorolac 30 mg IV. Every 6 hours the following parameters were registered: Visual Analogue Scale (VAS) at rest, VAS during movements, postoperative nausea and vomiting (PONV), pruritus, rescue analgesic medications requirements. The following data were also obtained: age and anthropometric data, number of pregnancies, educational level, OPRM1 genotype.


of the 63 patients enrolled, 45 (71%) were homozygous genotype A/A (118A group) while 18 carried the G variants of OPRM1 (A/G or G/G) (118G group). No significant differences in analgesic rescue doses administration and in incidence of moderate/severe post-operative pain (VAS>3) between the two groups were observed. Pruritus was more frequent in the 118A group than in the 118G group in the first 24 hours of the post-operative period.


in the Italian population there is a different incidence of pruritus in the post-cesarean period in response to intrathecal opioids related to OPRM1 gene polymorphism, but not of post-operative pain.

This study was awarded a fund by the “ENTE CASSA DI RISPARMIO DI FIRENZE” (protocol number 2013.0331) of 25000 Euros.

The authors declare no conflict of interest.

Reprints: Alessandro Di Filippo, MD, Department of Health Sciences. Section of Anaesthesia, Intensive Care and Pain Therapy, University of Florence, Careggi University Hospital, Largo Brambilla 3, 50124 Firenze Italy (e-mail:

Received February 18, 2017

Accepted May 31, 2017

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