Title {1}	Low dose naltrexone for the treatment of fibromyalgia: Protocol for a double-blind, randomized, placebo-controlled trial
Trial registration {2a and 2b}.	EudraCT-number.: 2019-000702-30 ClinicalTrials.gov Identifier: NCT04270877
Protocol version {3}	Version 5.0 (25.09.2020). Amendment: Version 5.1 (27.07.2021)
Funding {4}	The Danish Rheumatism Association has granted 175.000 DKK for operating expenses. Odense University Hospital’s PhD fund for operation expenses has granted 100.000 DKK towards operating expenses and the study nurse’s salary. Aase and Ejnar Danielsens fund has granted 100.000 DKK towards operating expenses and the study nurse’s salary. The Parker Institute at Bispebjerg and Frederiksberg Hospital is supported by a core grant from the Oak Foundation (OCAY-18-774-OFIL). The work of the Primary Investigator (KDB) is covered by a PhD salary.
Author details {5a}	Karin Due Bruun*1,2,3 karin.due.bruun@rsyd.dk Kirstine Amris3,4 kirstine.amris@regionh.dk Henrik Bjarke Vaegter1,2 hbv@rsyd.dk Morten Rune Blichfeldt-Eckhardt1,2 mr.be@rsyd.dk Anders Holsgaard-Larsen2,4 AHLarsen@health.sdu.dk Robin Christensen2,3 robin.christensen@regionh.dk Palle Toft2,6 palle.toft@rsyd.dk 1 Pain Research Group, Pain Center, Odense University Hospital, Odense, Denmark 2 Department of Clinical Research, Faculty of Health Sciences, University of Southern Denmark, Odense, Denmark 3 The Parker Institute, Bispebjerg and Frederiksberg Hospital, Copenhagen, Denmark 4 Department of Rheumatology, Bispebjerg and Frederiksberg Hospital, Copenhagen, Denmark 5 Department of Orthopedics and Traumatology, Odense University Hospital, Odense, Denmark 6 Department of Anesthesiology and Intensive Care, Odense University Hospital, Odense, Denmark
Name and contact information for the trial sponsor {5b}	Palle Toft, Professor, MD, PhD, Dr. Med. Department of Anesthesiology and Intensive Care Odense University Hospital Sdr. Boulevard 29 5000 Odense C Email: palle.toft@rsyd.dk
Role of sponsor {5c}	The study is investigator initiated.