Drug Interaction Report

GENERALLY AVOID: Concomitant use of opioids such as tramadol with other central nervous system (CNS) depressants such as aripiprazole may result in hypotension, profound sedation, respiratory depression, coma, and death.

MONITOR CLOSELY: Tramadol may prolong the QT interval, and while it is uncertain whether aripiprazole causes clinically significant prolongation of the QT interval, coadministration of multiple agents that can prolong the QT interval may theoretically result in additive effects and increased risk of ventricular arrhythmias including torsade de pointes and sudden death. The effect of tramadol on the QT interval was evaluated in a randomized, double-blind, 4-way crossover, placebo- and positive-controlled, multiple-dose ECG study of 62 healthy subjects. The maximum placebo-adjusted mean change from baseline in the Fridericia-corrected QT interval (QTcF) was 5.5 msec in the 400 mg/day treatment arm (100 mg every 6 hours on days 1 through 3 with a single 100 mg dose on day 4) and 6.5 msec in the 600 mg/day treatment arm (150 mg every 6 hours on days 1 through 3 with a single 150 mg dose on day 4), both occurring at the 8-hour time point. In clinical trials with aripiprazole involving patients with schizophrenia or bipolar mania, the incidence of QT prolongation was comparable to placebo. In postmarketing experience, QT prolongation, sudden death, torsade de pointes, ventricular tachycardia, arrhythmia, and cardiopulmonary arrest have been reported. However, these events were very rare or isolated, and many of the patients had preexisting cardiovascular disease, were on concomitant medications known to prolong the QT interval, had risk factors for QT prolongation, took an overdose of aripiprazole, and/or were morbidly obese. On the contrary, most data available in the medical literature suggest that aripiprazole either has no effect on the QT interval, or it may even cause a slight shortening of the QT interval within the dosage range of 10 to 30 mg/day.

MANAGEMENT: The use of tramadol in conjunction with aripiprazole should generally be avoided. If coadministration is necessary, the dosage and duration of each drug should be limited to the minimum required to achieve desired clinical effect. ECG monitoring may be advisable in some cases, such as in patients with a history of cardiac arrhythmias or congenital or family history of long QT syndrome. Particular care should be exercised in patients suspected to be at an increased risk of torsade de pointes. Patients should be advised to seek prompt medical attention if they experience symptoms that could indicate the occurrence of torsade de pointes such as dizziness, lightheadedness, fainting, palpitation, irregular heart rhythm, shortness of breath, or syncope. In addition, patients should be monitored closely for signs and symptoms of respiratory depression and sedation, and advised to avoid driving or operating hazardous machinery until they know how these medications affect them.

MONITOR: Coadministration with celecoxib may increase the plasma concentrations of drugs that are substrates of the CYP450 2D6 isoenzyme. The mechanism is decreased clearance due to inhibition of CYP450 2D6 activity by celecoxib.

MANAGEMENT: Caution is advised if celecoxib must be used concurrently with medications that undergo metabolism by CYP450 2D6, particularly those with a narrow therapeutic range. Dosage adjustments as well as clinical and laboratory monitoring may be appropriate for some drugs whenever celecoxib is added to or withdrawn from therapy.

MONITOR: Coadministration with inhibitors of CYP450 3A4 and/or 2D6 may increase the plasma concentrations of aripiprazole, which is primarily metabolized by these isoenzymes. According to the product labeling, administration of a single 15 mg dose of aripiprazole during treatment with the potent CYP450 3A4 inhibitor ketoconazole (200 mg/day for 14 days) increased the systemic exposure (AUC) to aripiprazole and its active metabolite, dehydro-aripiprazole, by 63% and 77%, respectively, compared to administration of aripiprazole alone. Likewise, administration of a 10 mg dose of aripiprazole with the potent CYP450 2D6 inhibitor quinidine (166 mg/day for 13 days) increased aripiprazole AUC by 112%, although dehydro-aripiprazole AUC was reduced by 35%.

MANAGEMENT: Pharmacologic response to aripiprazole should be monitored more closely whenever a CYP450 3A4 and/or 2D6 inhibitor is added to or withdrawn from therapy, and the aripiprazole dosage adjusted as necessary. The manufacturer recommends that aripiprazole dosage be reduced to one-half the normal dosage during concomitant administration with ketoconazole or quinidine, and additional dosage adjustments be made based on clinical evaluation. No dosage recommendations are available for concomitant administration with less potent CYP450 2D6 or 3A4 inhibitors.

GENERALLY AVOID: Alcohol may potentiate some of the pharmacologic effects of CNS-active agents. Use in combination may result in additive central nervous system depression and/or impairment of judgment, thinking, and psychomotor skills.

MANAGEMENT: Patients receiving CNS-active agents should be warned of this interaction and advised to avoid or limit consumption of alcohol. Ambulatory patients should be counseled to avoid hazardous activities requiring complete mental alertness and motor coordination until they know how these agents affect them, and to notify their physician if they experience excessive or prolonged CNS effects that interfere with their normal activities.

GENERALLY AVOID: Alcohol may potentiate some of the pharmacologic effects of CNS-active agents. Use in combination may result in additive central nervous system depression and/or impairment of judgment, thinking, and psychomotor skills.

MANAGEMENT: Patients receiving CNS-active agents should be warned of this interaction and advised to avoid or limit consumption of alcohol. Ambulatory patients should be counseled to avoid hazardous activities requiring complete mental alertness and motor coordination until they know how these agents affect them, and to notify their physician if they experience excessive or prolonged CNS effects that interfere with their normal activities.