Butorphanol-induced Precipitated Opioid Withdrawal With Stress Cardiomyopathy in the Setting of Chronic Fentanyl Use.

Precipitated opioid withdrawal due to partial opioid agonists other than buprenorphine is rarely reported. We present a case of severe precipitated opioid withdrawal and stress cardiomyopathy after butorphanol use in the setting of chronic fentanyl use. Emergency medical services responded to a 61-year-old female with opioid use disorder (OUD) who was severely agitated requiring multiple doses of sedatives. Emergency department examination was notable for extreme agitation and restlessness. An electrocardiogram showed sinus tachycardia without ischemic changes. Urine drug immunoassay was positive for benzodiazepines and fentanyl, despite no fentanyl administration by providers. A transthoracic echocardiogram showed evidence of stress cardiomyopathy. A subsequent comprehensive urine drug analysis was positive for norfentanyl and butorphanol. The patient confirmed using butorphanol immediately before the onset of symptoms. The patient's goals were to resume treatment of OUD with buprenorphine. She stabilized on buprenorphine 16 mg/4 mg sublingual film daily, then transitioned to buprenorphine long-acting injectable 96 mg subcutaneous monthly. Butorphanol is a synthetic partial agonist at the μ-opioid receptor and full agonist at the κ-opioid receptor. It is available in several formulations and is frequently used as a veterinary analgesic. Precipitated opioid withdrawal from butorphanol has been demonstrated in experimental settings but has not been described in clinical practice. This case emphasizes the importance of recognizing butorphanol as a partial opioid agonist capable of causing precipitated opioid withdrawal in the setting of chronic opioid agonist exposure, and underscores potential medical consequences of precipitated opioid withdrawal including stress cardiomyopathy.