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Super analgesia of intrathecal morphine may be related to ABCB1 (MDR1) gene polymorphism

Authors Qin WJ, Liu BT, Deng A, Liu Y, Zhang XL, Zhang L

Received 17 November 2017

Accepted for publication 1 April 2018

Published 20 July 2018 Volume 2018:11 Pages 1355—1357


Checked for plagiarism Yes

Review by Single anonymous peer review

Peer reviewer comments 4

Editor who approved publication: Dr E Alfonso Romero-Sandoval

Wangjun Qin,1,* Botao Liu,2,* Ang Deng,1 Ying Liu,1 Xianglin Zhang,1 Lei Zhang1

1Department of Pharmacy, China-Japan Friendship Hospital, Beijing, China; 2Department of Pain Management, China-Japan Friendship Hospital, Beijing, China

*These authors contributed equally to this work

Abstract: Intrathecal morphine provides superior analgesia and minimizes side effects with ~1/300th of the oral dose necessary to achieve this effect. The conversion ratios from oral route to intrathecal route vary greatly among individuals, and this may be related with polymorphisms of the ATP-binding cassette B1 (ABCB1)/multiple drug resistance 1 (MDR1) gene encoding the transporter P-glycoprotein in the blood–brain barrier. In the case presented herein, a patient with cancer pain for over 3 months was treated with oxycodone hydrochloride prolonged-release tablets (Oxycontin) and morphine hydrochloride tablets for breakthrough pain. The patient was admitted due to intolerable adverse effects of Oxycontin. During this admission, he was implanted with an intrathecal morphine pump which can deliver morphine into the cerebrospinal fluid. To our surprise, intrathecal morphine at a dose of ~1/540th of oral morphine equivalent dose produced complete analgesia. Our finding revealed homogenous CC at position 3435 (C3435T) in the ABCB1/MDR1 gene in this patient, which encodes P-glycoprotein with good efflux pump functionality. As intrathecal morphine bypasses the blood–brain barrier that oral ­medications have to pass through, the good pump functionality may have contributed to the super analgesia of intrathecal morphine in this case. Genetic analysis of ABCB1/MDR1 gene polymorphisms can be useful for personalized pain management in patients with intrathecal morphine pump.

Keywords: super analgesia, morphine, intrathecal morphine pump, gene polymorphism, ABCB1, MDR1

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