Received: 18 December 2020
Accepted: 26 February 2021
First Online: 11 March 2021
: This study was approved by the Clinical Research Ethics Committee of Tokai University School of Medicine (study code: 18I-25), and was conducted in accordance with approved protocols. Informed consent forms with written provision were completed by all patients before the donation of samples.
: <i>NAT2</i> genotyping data and intervertebral disc samples were obtained with written informed consent. All data are anonymized and no information is traceable to any individual patient. All authors have read the manuscript and agreed to its content. This work is original and is not currently under consideration by another journal. A funder provided research grant for this study, Nippon Zoki Pharmaceutical Company Ltd. consented to publish this manuscript.
: The authors, T.N., D.S., and M.W. received a research grant from Nippon Zoki Pharmaceutical Company Ltd. T.N. received a salary afforded by this grant. M.N. is employed by the company. Other authors, Y.N., N.H., and E.M. have no competing interests. The funder will not in any way gain or lose financially from the publication of this manuscript, either now or in the future. The authors do not hold any stocks or shares in an organisation that may in any way gain or lose financially from the publication of this manuscript, either now or in the future. The authors do not hold or currently applying for any patents relating to the content of the manuscript. The authors have not received reimbursements, fees, funding, or salary from an organization that holds or has applied for patents relating to the content of the manuscript. The authors do not have any other financial competing interests in relation to this paper.