Capsazepine

Capsazepine is a synthetic analogue of capsaicin.

Pharmacology
Capsazepine blocks the painful sensation of heat caused by capsaicin (the active ingredient of chilli pepper) which activates the TRPV1 ion channel. It is therefore considered to be a capsaicin antagonist. The TRPV1 channel functions as a pain and temperature sensor in mammalians. Capsazepine blocks only the activation of TRPV1 channels by chemicals but not by other painful stimuli, like heat. Depending on the pharmacological assay the half maximal inhibitory concentration IC50 is in the nanomolar to low micromolar range. In addition to its effects on TRPV1 channels it was also shown to inhibit the cold activated TRPM8 channel, voltage-activated calcium channels and nicotinic acetylcholine receptors. It mainly serves as a tool to study the TRPV1 ion channel.

Development
Capsazepine was discovered by a research group at the Sandoz Institute for Medical Research. Its synthesis and chemical properties were published in 1994. It was found by modification of the chemical backbone of capsaicin.