C101, a novel 4-amino-piperidine derivative selectively blocks N-type calcium channels.

N-type Ca2+ channels located on presynaptic nerve terminals regulate neurotransmitter release, including that from the spinal terminations of primary afferent nociceptors. Pharmacological and ion-channel gene knockdown approaches in animals have revealed N-type Ca2+ channels to be particularly attractive molecular targets for the discovery and development of new analgesic drugs. In recent years, some non-peptide small molecular N-type Ca2+ channel blockers have been reported. However, low selectivity and some side effects limit their further development. To overcome these disadvantages, some new compounds were designed and synthesized in our institute by optimizing the 4-amino-piperidine template. C101, one of these compounds, was demonstrated to block N-type Ca2+ channels with higher selectivity. It was found that C101 produced concentration-dependent inhibition on N-type Ca2+ channels expressed in Xenopus oocytes with an IC50 is 2.2+/-0.6 microM. The current-voltage relationship was not altered after 2-min exposure to C101. However, the steady-state inactivation relationship curve was shifted to more negative potentials for channels. Therefore, it seemed that C101 blocks the inactivated channel. C101 did not present any remarkable effects on voltage-gated potassium, sodium channels in cultured rat hippocampal neurons, and L-, P/Q-, R-type calcium channels and HERG channels expressed in Xenopus oocytes. The results suggested that C101 was a high selective blocker targeting N-type Ca2+ channels, and may have a potential to be developed as a novel analgesic agent.