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

Area of Science:

• Pulmonology
• Pharmacology
• Toxicology

Background:

• Naltrexone is an opioid antagonist used for alcohol and opioid dependence.
• Injectable naltrexone offers a long-acting alternative to oral formulations.
• Acute eosinophilic pneumonia (AEP) is a rare respiratory illness with various potential causes, including medications.

Observation:

• A patient receiving injectable naltrexone developed acute respiratory symptoms including dyspnea and hypoxia.
• Chest imaging revealed diffuse bilateral pulmonary infiltrates and laboratory tests showed mild peripheral eosinophilia.
• Initial treatment for community-acquired pneumonia was unsuccessful, prompting a switch to steroids for suspected drug-induced AEP.

Findings:

• Bronchoalveolar lavage (BAL) fluid showed lymphocyte predominance, but lung biopsy confirmed drug-induced eosinophilic pneumonitis.
• The patient's hypoxia resolved with steroid therapy, and she was discharged on oral steroids and bronchodilators.
• Despite initial diagnostic challenges, the case highlights naltrexone as a potential cause of AEP.

Implications:

• This case underscores the importance of considering medication side effects, particularly naltrexone, in the differential diagnosis of AEP.
• Prompt recognition and management of drug-induced AEP with corticosteroids can lead to excellent patient outcomes.
• Further research may be warranted to elucidate the mechanisms of naltrexone-induced lung injury.