• Y Zhang, K Wang, L Arendt-Nielsen, and B E Cairns.
• Center for Neuroplasticity and Pain, SMI, Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Aalborg, Denmark.
• Eur J Pain. 2018 Feb 1; 22 (2): 393-401.

BackgroundIn burning mouth patients, analgesia after oral administration of clonazepam may result from modulation of peripheral γ-aminobutyric acid (GABA) receptors.MethodsThe effect of oral administration of test solutions (water, 0.5 mol/L or 0.05 mol/L GABA, 1% lidocaine) was investigated for the amelioration of pain and sensitivity induced by application of capsaicin (1%, 2 min) to the tongue of thirty healthy male and female subjects in this four-session, randomized, placebo-controlled, double-blinded, cross-over study. Intra-oral quantitative sensory testing was used to assess cold (CDT), warm (WDT) and mechanical (MDT) detection thresholds as well as mechanical (MPT) and heat (HPT) pain thresholds. Capsaicin-induced pain intensity was continuously rated on a 0-10 electronic visual analogue scale (VAS). The area under the VAS curve (VASAUC) after rinsing was calculated for each solution.ResultsCapsaicin application on the tongue evoked burning pain with a peak of 4.8/10, and significantly increased CDT and MDT while significantly decreasing WDT, HPT, and MPT. The VASAUC was significantly smaller after oral rinse with 0.05 mol/L GABA, 0.5 mol/L GABA, and 1% lidocaine than after oral rinse with water. Rinse with 0.5 mol/L or 0.05 mol/L GABA were similarly effective in decreasing VASAUC. Rinsing with either 1% lidocaine, 0.5 mol/L or 0.05 mol/L GABA also significantly attenuated the effects of capsaicin on WDT and HPT in a treatment independent manner. There were no sex-related differences in these effects of GABA.ConclusionsCapsaicin-induced burning tongue pain and decreases in WDT and HPT can be ameliorated by rinsing the mouth with lidocaine and GABA solutions.SignificanceRinsing the mouth with an oral GABA containing solution ameliorated burning pain and increased heat sensitivity produced by application of capsaicin to the tongue. This finding suggests that GABA can act as a local analgesic agent in the oral cavity.© 2017 European Pain Federation - EFIC®.

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