Pain has been a human problem since the beginning of time but the last decade has
seen an explosion of information about the transmitters, receptors and channels
involved in the transmission and modulation of noxious messages generated in
peripheral tissues. This has lead to the identification of a number of potential new
targets for analgesic therapy. We now have more experimental drugs available, which
allows us to study the roles of transmitters and receptors in physiological events. There
are now numerous animal models for clinical pain states such as inflammation and
neuropathies, and these models have shown that several transmitter systems which
have minor actions in acute pains can play important roles in more persistent pains.