Grapefruit juice and verapamil: a toxic cocktail

South Med J. 2009 Mar;102(3):308-9. doi: 10.1097/SMJ.0b013e3181928f81.

Abstract

The US public consumes grapefruit juice in large quantities, with 14% of the population drinking the juice at least weekly. Grapefruit juice is a well-documented inhibitor of the CYP3A4 isoenzyme, which is involved in the metabolism of over 50% of commonly prescribed drugs. Here we report an unusual case of verapamil toxicity in a 42-year-old female, which resulted from accidental ingestion of only three tablets of the sustained release preparation (120 mg each) over 24 hours which resulted in severe toxicity.

Publication types

  • Case Reports

MeSH terms

  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / drug effects
  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / metabolism
  • Adult
  • Calcium Channel Blockers / pharmacokinetics
  • Calcium Channel Blockers / poisoning*
  • Citrus paradisi / adverse effects*
  • Cytochrome P-450 CYP3A / drug effects
  • Cytochrome P-450 CYP3A / metabolism*
  • Drug Interactions
  • Drug Overdose
  • Female
  • Humans
  • Respiration, Artificial
  • Verapamil / pharmacokinetics
  • Verapamil / poisoning*

Substances

  • ATP Binding Cassette Transporter, Subfamily B, Member 1
  • Calcium Channel Blockers
  • Verapamil
  • Cytochrome P-450 CYP3A
  • CYP3A4 protein, human