QX-314 (chloride)

QX-314 is a membrane-impermeant lidocaine derivative that selectively blocks sodium channels on nociceptive neurons when delivered intracellularly via the TRPV1 channel, but is reportedly ineffective with extracellular application.¹ When supplied in combination with 1 µM capsaicin (Item No. 92350), a TRPV1 receptor agonist, 5 mM QX-314 blocks 98% of sodium current in voltage-clamped nociceptive DRG neurons.¹ QX-314 elicits a long-lasting decrease in the response to painful mechanical and thermal stimuli without imparting the motor deficits (e.g., numbness, paralysis) associated with many conventional local anesthetics.¹ At concentrations ranging from 10-70 mM, peripheral application of QX-314 dose-dependently produces robust local anesthesia with slow onset in the guinea pig intradermal wheal assay, the mouse tail-flick test, and the mouse sciatic nerve blockade model.² However, injection of 0.5-30 mM QX-314 in the lumbar intrathecal space produces neurotoxicity and death in mice.³

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1. Binshtok, A.M., Bean, B.P., and Woolf, C.J. Inhibition of nociceptors by TRPV1-mediated entry of impermeant sodium channel blockers. Nature 449, 607-610 (2007).

2. Lim, T.K.Y., MacLeod, B.A., Ries, C.R., et al. The quaternary lidocaine derivative, QX-314, produces long-lasting local anesthesia in animal models in vivo. Anesthesiology 107, 305-311 (2007).

3. Schwarz, S.K.W., Cheung, H.M.C., Ries, C.R., et al. Lumbar intrathecal administration of the quaternary lidocaine derivative, QX-314, produces irritation and death in mice. Anesthesiology 113, 438-444 (2010).