The warnings on the label of desipramine (Norpramin), a tricyclic antidepressant, have been revised (go to http://bit.ly/d064qf). Because the drug can produce conduction defects, arrhythmias, tachycardia, strokes, and acute myocardial infarction, the label had already warned prescribers to use extreme caution when giving the drug to patients with a history of cardiovascular disease. Now the scope of the warning has been broadened to include patients with a family history of sudden death, cardiac arrhythmias, or cardiac conduction disturbances. Another new warning is that desipramine must be used with extreme caution in patients with a history of seizure disorder because the drug can lower the seizure threshold, precipitating seizures; some patients have had seizures that preceded cardiac arrhythmias and death.

Further, according to the manufacturer, overdoses of desipramine are more likely to cause death than are overdoses of other tricyclic antidepressants. Electrocardiographic changes can occur in overdosage, including a widening of the QRS complex, the presence of a terminal S wave seen in lead I and aVL, and an R wave seen in aVR.

Nurses should assess patients carefully for these risk factors if they're to begin therapy with desipramine and teach patients and their families about possible adverse effects. Because all antidepressants carry a warning of an increased risk of suicidality or suicide, families should be aware of the signs of depression and notify the physician or NP if depression occurs or worsens. The patient may take an overdose as a suicide attempt, and the cardiovascular adverse effects from overdosage may be fatal.