Table 3. hNav1.8 Potency (IC50), Selectivity (IC50), and Antiallodynic Effects in Rodent Models of Neuropathic Pain for 3, 13, and 18a.
hNav1.8 | hNav subtype selectivity | TTX-r Rat DRG | TTX-R human DRG | hERG | ||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Cmpd | IC50 (μM) | n | IC50 (μM) | n | IC50 (μM) | n | IC50 (μM) | n | IC50 (μM) | Model | Effect significance | Unbound exposure (μM) |
3 | 0.19 | 5 | Nav1.1 = 13 | 5 | 0.44 | 4 | 0.31 | 4 | 30 | SNL hypersensitivity | P < 0.05 (equal to 100 mg/kg gabapentin) | 0.25 |
Nav1.2 = 12.8 | 5 | |||||||||||
Nav1.5 = 9.0 | 5 | |||||||||||
Nav1.7 = 19 | 5 | |||||||||||
13 | 0.19 | 2 | Nav1.1 = 37 | 2 | 0.54 | 4 | 0.20 | 3 | >30 | TNT mechanical allodynia | SP < 0.05 (comparable to 10 mg/kg pregabalin) | 0.20 |
Nav1.5 = 37 | 2 | |||||||||||
Nav1.7 = 36 | 2 | |||||||||||
18 | 0.26 | 4 | SHSY5Yb = 10 Nav1.5 = 12 |
5 | 0.33 | 6 | ND | >30 | TNT mechanical allodynia | P < 0.05 (comparable to 10 mg/kg pregabalin) | 0.19 | |
4 |
IC50 values for 3, 13, and 18 at recombinantly expressed hNav1.8/β1 (Merck Millipore) and at TTX-R in rat and human DRG were determined using manual patch clamp electrophysiology. hNav subtype selectivity for 3 was also measured using manual patch clamp electrophysiology. IC50 values determined using manual patch clamp electrophysiology were determined at the respective V0.5 of inactivation for TTX-R and each channel isoform. For 13 and 18, human sodium channel subtype selectivity was measured using IonWorks Quattro and FRET, respectively.
SHSY5Y cells expressing hNav1.2, 1.3, and 1.7 were also used. The voltage protocol for the IonWorks Quattro and assay methodology for the FRET assay is detailed in the Supporting Information.