[Opiate receptors]

In view of the basic principles of the receptor theory, one should expect all opioids to exhibit principally the same spectrum of effects, as they exert their actions by interaction with "the opiate receptor." Clinical experience shows, however, that the opioids in clinical usage in fact exhibit a variety of spectra of effects. This discrepancy is explained by introducing the "multiple receptor theory," as developed by Gilbert and Martin. This review attempts to class practical clinical consequences with those more recent pharmacological findings.