Lesson of the month 1: A rare adverse reaction between flucloxacillin and paracetamol

Area of Science:

• Pharmacology
• Toxicology
• Metabolic Disorders

Background:

• Flucloxacillin is a widely prescribed beta-lactam antibiotic for staphylococcal and streptococcal infections.
• Paracetamol is a common analgesic and antipyretic medication dispensed by NHS England.
• The potential for a severe drug interaction between these two medications is often unrecognized by healthcare providers.

Observation:

• A case report details a patient with multiple comorbidities who developed pyroglutamic acidosis (PGA).
• PGA was attributed to the concurrent administration of paracetamol and flucloxacillin.

Findings:

• Pyroglutamic acidosis (PGA), also termed 5-oxoprolinaemia, is a rare cause of elevated anion gap metabolic acidosis.
• The underlying mechanism of PGA involves disruption of the gamma-glutamyl cycle.

Implications:

• Highlights a potentially fatal drug interaction between commonly used medications.
• Underscores the need for increased clinician awareness regarding the concurrent use of flucloxacillin and paracetamol.
• Suggests careful patient monitoring for metabolic acidosis when these drugs are co-administered, especially in vulnerable populations.