nortriptyline
n. a tricyclic antidepressant, a so-called secondary tricyclic, that is the principal metabolic product of amitriptyline. Although its clinical efficacy is the same as other tricyclics, nortriptyline and the other secondary tricyclic agent, desipramine, were often preferred because they are less sedating and have fewer anticholinergic effects. A therapeutic window is thought to exist for nortriptyline: Although plasma levels do not always correlate with clinical effectiveness, optimum responses are thought to occur when serum levels of the drug are between 50 and 150 ng/ml. Plasma levels over 500 ng/ml are toxic. The availability of newer antidepressants that do not require therapeutic monitoring has led to a decline in its use. U.S. trade names: Aventyl; Pamelor.