Major determinant factors of the extent of interaction between grapefruit juice and calcium channel antagonists

Ayako Ohnishi, Hisakazu Ohtani, Yasufumi Sawada

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15 Citations (Scopus)


Aim: To evaluate quantitatively the influence of bioavailability and plasma unbound fraction (fu) on the extent of interaction between grapefruit juice (GFJ) and calcium antagonists. Methods: The extent of drug-GFJ interaction was evaluated from reported clinical interaction studies of 11 calcium antagonists. The relationship between extent of interaction and bioavailability or fu was analysed. Results: The following significant hyperbolic relationships were observed: [Extent] = 12.2/[bioavailability] + 1 and [Extent] = 0.718/[fu ] + 1. Conclusions: Bioavailability and fu are major determinant factors of calcium antagonist-GFJ interaction: a drug with smaller bioavailability or lower fu is likely to exhibit a more potent interaction, and vice versa.

Original languageEnglish
Pages (from-to)196-199
Number of pages4
JournalBritish journal of clinical pharmacology
Issue number2
Publication statusPublished - 2006 Aug 1



  • Calcium antagonist
  • Determinant factor
  • Grapefruit juice
  • Interaction

ASJC Scopus subject areas

  • Pharmacology
  • Pharmacology (medical)

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