NCIt definition : A centrally-acting neurokinin 1 (NK1) receptor antagonist with antidepressant and
antiemetic activities. Casopitant competitively binds to and blocks the activity of
the NK-receptor, thereby inhibiting NK1-receptor binding of the endogenous tachykinin
neuropeptide substance P (SP), which may result in antiemetic effects. SP is found
in neurons of vagal afferent fibers innervating the brain-stem nucleus tractus solitarii
and the area postrema, which contains the chemoreceptor trigger zone (CTZ), and may
be elevated in response to chemotherapy. The NK-receptor is a G-protein receptor coupled
to the inositol phosphate signal-transduction pathway and is found in both the nucleus
tractus solitarii and the area postrema.;