Multiorgan Failure After Phentermine Overdose.

Phentermine is the most prescribed anorexiant in the United States. There is a paucity of literature on consequences of phentermine overdose.1 We present a case of multiorgan failure secondary to phentermine self-overdose in an elderly male. A 69-year-old man with a history of epilepsy, major depressive disorder, prior methamphetamine abuse, schizophrenia, suicidal ideation, and cerebrovascular accident presented to the emergency department following intentional overdose of approximately 750 mg of phentermine. His home medications included quetiapine, aspirin, lisinopril, and phentermine. Urine drug analysis was positive for amphetamines, tricyclics, and bupropion. Acetaminophen, salicylate, and alcohol were not detected in the toxicology screen. A phentermine blood level was not ordered. Upon presentation, the patient was alert and able to follow commands while endorsing excessive muscle twitching and spastic movements. Vital signs upon presentation revealed a temperature of 36.7°C, heart rate of 135 beats/minute, respiratory rate of 24 breaths/minute, blood pressure of 185/125 mm Hg, and oxygen saturation of 94% on room air. He was tachycardic, tachypneic, and hypertensive. An electrocardiogram demonstrated atrial fibrillation followed by regular, narrow complex supraventricular tachycardia with a right bundle branch block. Atelectasis was seen in the left lung base. Initial labs were significant for leukocytosis, acute kidney injury, rhabdomyolysis, metabolic acidosis, and transaminitis. Computed tomography of the head and chest was unremarkable. An echocardiogram revealed an ejection fraction of 10% to 15%, akinetic apex, and multiple areas of hypokinesis consistent with stress cardiomyopathy. He subsequently became more agitated requiring intubation and ICU admission. Emergent hemodialysis was required given worsening acidosis, kidney injury, hyperkalemia, and rhabdomyolysis. The patient also received brief use of vasopressors. The creatine kinase peaked at 14 000 U/L, and troponin concentration peaked at 38 ng/mL before trending down. The patient’s acute renal failure and anion gap metabolic acidosis were corrected after 2 rounds of dialysis. He was extubated after 5 days of ventilation. On day 11, the patient was discharged to a skilled nursing facility. Phentermine is a centrally acting sympathomimetic amine that suppresses appetite and assists with short-term weight loss.1 Phentermine has a high potential of misuse. Adverse effects of tachycardia, decreased visual acuity, nausea, sleeplessness, anxiety, psychosis, and manic-like episodes are linked with phentermine therapy.2 Cardiac complications can arise due to enhanced AV nodal conduction effects from a similar structure to amphetamine.3 Case reports have described the development of prolonged QT interval and polymorphic ventricular tachycardia, supraventricular tachycardia, and recurrent ventricular fibrillation with cardiac vasospasm.3 One case report described the onset of rhabdomyolysis in a patient who took double the recommended amount of phentermine over 1 week.4 To our knowledge, this is the first case that reports multiorgan failure associated with a phentermine overdose. Our patient’s clinical course was a probable result of phentermine overdose. Use of the Naranjo Scale revealed a score of 6 based on the patient’s presentation, onset, and resolution of symptoms after phentermine consumption.5 Generally, phentermine is prescribed to the younger female population in conjunction with an established diet plan. In our case, an older male was prescribed phentermine to aid with his weight loss. Prior amphetamine abuse and psychiatric history were factors that may have increased the patient’s risk of phentermine abuse.