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Grapefruit juice and verapamil: a toxic cocktail
Unnikrishnan Pillai1, Jameel Muzaffar, Sandeep Sen
1Internal Medicine and the Medical Clinic, St. Mary's Health Center, St. Louis, MO 63117, USA. unnikrishnanpk@yahoo.com
Southern Medical Journal
|February 11, 2009
Summary
Grapefruit juice inhibits drug metabolism, leading to potential toxicity. A case report details severe verapamil toxicity from accidental ingestion due to this interaction.
Area of Science:
- Pharmacology
- Toxicology
- Drug Metabolism
Background:
- Grapefruit juice consumption is widespread in the US.
- Grapefruit juice is a known inhibitor of the CYP3A4 enzyme.
- CYP3A4 metabolizes over 50% of commonly prescribed medications.
Observation:
- A 42-year-old female experienced severe toxicity.
- The toxicity resulted from accidental ingestion of three 120 mg sustained-release verapamil tablets over 24 hours.
Findings:
- This case highlights the potential for severe drug toxicity.
- Even a small dose of sustained-release verapamil can cause toxicity when combined with grapefruit juice.
- The interaction is attributed to grapefruit juice's inhibition of CYP3A4.
Implications:
- Patients taking verapamil or other CYP3A4-metabolized drugs should avoid grapefruit juice.
- Healthcare providers should counsel patients on potential drug-food interactions.
- This case underscores the importance of medication adherence and awareness of dietary influences on drug efficacy and safety.
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