How does Pamelor work to treat panic disorder?

Doctors are not sure how the antidepressant Pamelor (nortriptyline) works to treat panic disorder. Although the Food and Drug Administration has approved Pamelor for treating depression in adults, it is sometimes prescribed "off label" to people who have panic disorder. Doctors think that Pamelor might help treat panic disorder by balancing the levels of certain chemicals in the brain, called neurotransmitters.

Pamelor belongs to a class of drugs called tricyclic antidepressants. In studies, about two-thirds of people with panic disorder who took a tricyclic antidepressant were panic free at the end of three months.