Interaction between methadone and clarithromycin as the suspected cause of an opioid toxidrome

Area of Science:

• Clinical Pharmacology
• Internal Medicine
• Pharmacovigilance

Background:

• Opioid dependence is a significant public health issue, often managed with methadone maintenance therapy.
• Community-acquired pneumonia is a common infection requiring antibiotic treatment.
• Drug interactions can lead to unexpected and severe adverse events, impacting patient safety.

Observation:

• Concomitant administration of methadone and clarithromycin led to an opioid toxidrome.
• Symptoms included type-2 respiratory failure, decreased consciousness, and pinpoint pupils.

Findings:

• The patient's symptoms resolved following naloxone administration.
• A potential drug interaction between clarithromycin and methadone was suspected as the cause.

Implications:

• This case highlights a previously unreported interaction between clarithromycin and methadone.
• Physicians and pharmacists must be aware of this potential interaction to prevent serious adverse events like respiratory failure.