Human safety study of a selective neuronal adenylate cyclase 1 inhibitor NB001 which relieves the neuropathic pain and blocks ACC in adult mice

Abstract

Calcium-dependent, neuronal adenylyl cyclase subtype 1 (AC1) is critical for cortical potentiation and chronic pain. NB001 is a first-in-class drug acting as a selective inhibitor against AC1. The present study delineated the pharmacokinetic (PK) properties of human-used NB001 (hNB001) formulated as immediate-release tablet. This first-in-human (FIH) study was designed as randomized, double-blind, placebo-controlled trial. hNB001 showed placebo-like safety and good tolerability in healthy volunteers. A linear dose-exposure relationship was demonstrated at doses between 20 mg and 400 mg. The relatively small systemic exposure of hNB001 in human showed low bioavailability of this compound through oral administration, which can be improved through future dosage research. Food intake had minimal impact on the absorption of hNB001 tablet. Animal experiments further confirmed that hNB001 had strong analgesic effect in animal models of neuropathic pain. In brain slice prepared from the anterior cingulate cortex (ACC), bath application of hNB001 blocked the induction of long-term potentiation (LTP). These results from both rodents and human strongly suggest that hNB001 can be safely used for the future treatment of different types of chronic pain in human patients.

Keywords: NB001; anterior cingulate cortex; effectiveness; first-in-human study; pharmacokinetics; safety; tolerability.

Figure 1.

Linear scale plasma concentration-time curve after single oral. Linear Scale of mean drug concentrations profile following single oral administration of 20 mg (n = 3), 50 mg (n = 6), 100 mg (n = 6), 200 mg (n = 6), 300 mg (n = 6), and 400 mg (n = 6) hNB001 tablet in 0–12 h in human.

Figure 2.

Semi-logarithmic scale plasma concentration-time curve after single oral. Semi-logarithmic scale of mean (SD) drug concentrations profile following single oral administration of 20 mg (n = 3), 50 mg (n = 6), 100 mg (n = 6), 200 mg (n = 6), 300 mg (n = 6), and 400 mg (n = 6) hNB001 tablet in 0–48 h in human.

Figure 3.

Proportional dose relationship after a single oral administration. (a) Proportional dose relationship of C_max after a single oral administration of 20 mg, 50 mg, 100 mg, 200 mg, 300 mg and 400 mg hNB001 tablet in human. (b) Proportional dose relationship of AUC_0-last after a single oral administration of 20 mg, 50 mg, 100 mg, 200 mg, 300 mg and 400 mg hNB001 tablet in human. (c) Proportional dose relationship of AUC_0-inf after a single oral administration of 20 mg, 50 mg, 100 mg, 200 mg, 300 mg and 400 mg hNB001 tablet in human.

Figure 4.

Effect of hNB001 on acute pain. (a) Comparison of behavioral responses to non-noxious mechanical stimulus. There was no significant difference in hind paw withdrawal to von Frey filaments before and after intragastric injection of saline (n = 15) and 40 mg/kg hNB001 (n = 15). (b) Effect of hNB001 in tail-flick (TF) test. hNB001 (10 mg/kg i. g.) did not affect spinal nociceptive TF reflex (n = 10 for hNB001 group and n = 10 for control group). (c) Effect of hNB001 in hot-plate test at 55°C. There was no significant difference in response latency before and after intragastric injection of saline (n = 8) and hNB001 (10 mg/kg) (n = 12).

Figure 5.

Effect of hNB001 on neuropathic pain. (a) Schematic diagram showing the common peroneal nerve (CPN) model. The sciatic nerve has three terminal branches: the sural nerve (SN), CPN, and tibial nerve (TN). The CPN was ligated but leaving the TN and SN intact. (b) Effect of hNB001 on mechanical threshold after common peroneal nerve (CPN) ligation (left) and sham surgery (right). Intragastric administration of hNB001 (40 mg/kg body weight) given 45 min before von Frey testing produced a significant analgesic effect (n = 13 for CPN group and n = 10 for sham group). Mechanical threshold was measured before the ligation surgery, 7 days after the surgery and at 45 min after intragastric application of hNB001. ***p<0.001compared with before surgery, #p < 0.05 compared with 7 days after surgery.

Figure 6.

Effect of hNB001 on the LTP of the fEPSPs induction in the ACC. (a) Two mapped figures show the evoked field potentials in the ACC with (left) and without (right) the application of 10 μM hNB001. Field potentials were recorded from the other 63 channels 0.5 h before (black) and 2 h (red) after TBS being delivered to one channel marked as “s”. (b) The fEPSP slope (bottom) and the superimposed samples (top) from one channel show that hNB001 blocked the induction of LTP (red circles) but the control group without hNB001 remains the LTP intact (black squares). (c) The summarized fEPSP slopes show that hNB001 blocked potentials from seven slices in three mice (red circles). The summarized fEPSP slopes show that LTP from four slices in three mice (black squares).

Figure 7.

Effect of NB001 on the recruited responses induced by TBS. (a) Baseline areas of activated sites with fEPSPs (blue) was not enlarged after TBS (red) in the presence of hNB001 (10 μM). (b) Polygonal diagrams of showed the baseline areas of the activated sites with fEPSPs (blue) and the enlarged areas after TBS (red) in normal slices without hNB001. Overlapped blue or red regions indicated the high frequently activated areas. (c) Summarize number of recruited channels (n = 7 slices/3 mice for hNB001 group and n = 6 slices/3 mice for saline group) that are activated before and after TBS induction. (d) Summarized results showing the temporal changes of the EPSP amplitude.