A Case for Biopsy: Injectable Naltrexone-Induced Acute Eosinophilic Pneumonia

Naltrexone is a semi-synthetic opioid that has competitive antagonist activity at mu opioid receptors. Naltrexone has proven to be efficacious in the treatment of alcohol and opioid dependence, and a long-acting injectable form of naltrexone was developed to overcome non-compliance. Therefore, injectable naltrexone has the potential to become an important medication for the treatment of opiate and alcohol dependence. Acute eosinophilic pneumonia (AEP) is a rare acute respiratory illness of varying severity that may lead to acute respiratory distress syndrome and death. Initially, AEP was thought to be idiopathic; however, it has become apparent that AEP can have identifiable causes including medications, infections, and other inhalational exposures, especially tobacco smoke. AEP is generally a diagnosis of exclusion confirmed by the presence of bronchoalveolar lavage (BAL) fluid eosinophilia. Recognition and elimination of the causative factor for AEP and providing glucocorticoid therapy are key principles in the management of AEP of non-infectious origin. Prognosis is generally excellent if AEP is diagnosed early and managed appropriately, even in patients with acute respiratory failure. The diagnosis of AEP is generally overlooked given the shared clinical attributes with acute lung injury due to other causes, including severe community-acquired pneumonia. A 32-year-old lady presented to the emergency department (ED) with symptoms of dyspnea, chest pain, cough, and subjective fevers since three days. She received a dose of intramuscular Naltrexone for the treatment of alcohol and opiate dependence on the day of symptom onset. Initially, she was noted to be hypoxic, and oxygen supplementation was initiated through a nasal cannula. While in the ED, she was placed on a non-rebreather mask because of worsening hypoxia. Chest imaging showed diffuse bilateral pulmonary infiltrates. Initial laboratory data were pertinent for elevated WBC count with mild peripheral eosinophilia. Antibiotics were administered for the treatment of suspected community-acquired pneumonia. Upon hospital admission, she was started on steroids for the management of suspected eosinophilic pneumonia secondary to injectable naltrexone. Bronchodilator therapy was initiated, and antibiotics were discontinued. The patient's oxygen requirements improved. Pulmonology consultation was requested, and the patient underwent bronchoscopy. BAL studies showed predominance of lymphocytes with no eosinophils. However, lung biopsy showed findings consistent with drug-induced eosinophilic pneumonitis. The patient's hypoxia resolved with steroid therapy. The patient was discharged with a course of oral steroids, albuterol inhaler, and outpatient pulmonology follow-up.