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Evaluation of the protein biomarkers and the analgesic response to systemic methylene blue in patients with refractory neuropathic pain: a double blind, controlled study
Multidisciplinary Pain Clinic, Uppsala University Hospital, Sweden.
Multidisciplinary Pain Clinic, Uppsala University Hospital, Sweden.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
2015 (English)In: Journal of Pain Research, ISSN 1178-7090, E-ISSN 1178-7090, Vol. 8, 387-397 p.Article in journal (Refereed) Published
Abstract [en]


This study was carried out in patients with neuropathic pain in order to assess the analgesic effects and changes in protein biomarkers after the administration of methylene blue (MB), a diaminophenothiazine with antioxidant and anti-inflammatory properties, and with inhibitory effects on nitric oxide.

Materials and methods:

Ten patients with chronic refractory neuropathic pain were randomized to receive either MB (10 mg/mL Methylthioninium chloride) 2 mg/kg (MB group) or MB 0.02 mg/kg (control group) infused over 60 minutes. Sensory function and pain (Numerical Rating Scale) were evaluated at baseline and at 60 minutes after the start of the infusion. The patients kept a pain diary during the next 24 hours and for the following 4 days. Plasma and urinary concentrations of 8-isoprostane-prostaglandin F2α (8-iso-PGF2α) and plasma protein biomarkers prior to and after the infusions were measured with radioimmunoassay and with proximity extension assay.


A decrease of the Numerical Rating Scale at 60 minutes in comparison with baseline was observed in the MB (P=0.047) group. The decrease was significant between the MB and the control group on the day of and day after MB infusion (P=0.04 and P=0.008, respectively). There was no difference in systemic protein expressions between groups except for prolactin (PRL) (P=0.02). Three patients demonstrated diminished dynamic mechanical allodynia.


MB decreased the pain levels in patients with chronic therapy-resistant neuropathic pain on the first 2 days after administration. Known as an endocrine modulator on the anterior pituitary gland, MB infusion produced a decrease of PRL. The detailed role of PRL effects in chronic neuropathic pain remains undetermined.

Place, publisher, year, edition, pages
2015. Vol. 8, 387-397 p.
National Category
Anesthesiology and Intensive Care
Research subject
Anaesthesiology and Intensive Care
URN: urn:nbn:se:uu:diva-280189DOI: 10.2147/JPR.S84685OAI: diva2:910312
Available from: 2016-03-08 Created: 2016-03-08 Last updated: 2017-11-30Bibliographically approved

Open Access in DiVA

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