Drug Interactions between atomoxetine and Dynex HD

MONITOR: Coadministration of two or more sympathomimetic agents may increase the risk of adverse effects such as nervousness, irritability, and increased heart rate. Central nervous system (CNS) stimulants, particularly amphetamines, can potentiate the adrenergic response to vasopressors and other sympathomimetic agents. Additive increases in blood pressure and heart rate may occur due to enhanced peripheral sympathetic activity.

MANAGEMENT: Caution is advised if two or more sympathomimetic agents are coadministered. Pulse and blood pressure should be closely monitored.

MONITOR: Serotonin syndrome has been reported following the concomitant use of atomoxetine with other serotonergic medicinal products. The use of agents with serotonergic activity (such as selective serotonin reuptake inhibitors (SSRIs), serotonin-norepinephrine reuptake inhibitors (SNRIs), monoamine oxidase inhibitors (MAOIs), tetracyclic antidepressants, tricyclic antidepressants, 5-HT1 receptor agonists (triptans), ergot alkaloids, lithium, St. John's wort, phenylpiperidine opioids, dextromethorphan, and tryptophan, among others) may potentiate the risk of serotonin syndrome, a rare but serious and potentially fatal condition. Symptoms of serotonin syndrome may include mental status changes such as irritability, altered consciousness, confusion, hallucination, and coma; autonomic dysfunction such as tachycardia, hyperthermia, diaphoresis, shivering, blood pressure lability, and mydriasis; neuromuscular abnormalities such as hyperreflexia, myoclonus, tremor, rigidity, and ataxia; and gastrointestinal symptoms such as abdominal cramping, nausea, vomiting, and diarrhea.

MANAGEMENT: Some authorities advise caution and closer monitoring for serotonin syndrome when atomoxetine is coadministered with other serotonergic agents, especially during initiation and dose escalations. Patients should be instructed to promptly notify their healthcare provider if they experience symptoms of serotonin syndrome. If serotonin syndrome is suspected, a dose reduction or discontinuation of therapy should be considered depending on the severity of the symptoms. If serotonin syndrome develops during therapy, all serotonergic agents should be discontinued immediately and supportive care rendered as necessary. Due to variability and occasionally prolonged half-lives of these coadministered agents, consulting individual product labeling for specific guidance is advised.