Interactions between haldol-decanoate(haloperidol) and Aventyl hcl (nortriptyline)
haloperidol and nortriptyline (Major Drug-Drug)
MONITOR CLOSELY: Haloperidol can cause dose-related prolongation of the QT interval. Theoretically, coadministration with other agents that can prolong the QT interval may result in elevated risk of ventricular arrhythmias, including ventricular tachycardia and torsade de pointes, because of additive arrhythmogenic potential related to their effects on cardiac conduction. Haloperidol treatment alone has been associated with a number of reported cases of torsade de pointes and sudden death. The majority of cases involved intravenous administration or use of higher than recommended dosages. Tricyclic antidepressants have also been reported to prolong the QT interval and cause torsade de pointes arrhythmia, usually in overdose or in combination with other drugs that prolong the QT interval such as neuroleptic or antiarrhythmic agents. In general, the risk of an individual agent or a combination of agents causing ventricular arrhythmia in association with QT prolongation is largely unpredictable but may be increased by certain underlying risk factors such as congenital long QT syndrome, cardiac disease, and electrolyte disturbances (e.g., hypokalemia, hypomagnesemia). In addition, the extent of drug-induced QT prolongation is dependent on the particular drugs involved and dosages of the drugs.
MONITOR CLOSELY: Haloperidol may increase the serum concentrations of tricyclic antidepressants by inhibiting their metabolism via CYP450 2D6. There have been case reports of seizures associated with this interaction.
MANAGEMENT: Caution is advised if haloperidol is used in combination with other drugs that prolong the QT interval, particularly when administered intravenously or at higher than recommended dosages. Haloperidol is not approved by the FDA for intravenous administration. Lower dosages of the tricyclic antidepressant may be necessary when used with haloperidol. Patients should be advised to notify their physician if they experience excessive tricyclic antidepressant adverse effects such as dry mouth, visual disturbances, urinary retention, dizziness, orthostasis, constipation, and seizures. In addition, patients should be advised to seek medical attention if they experience symptoms that could indicate the occurrence of torsades de pointes such as dizziness, palpitations, or syncope.
