Tier 2 — strong

Quercetin, an in vitro inhibitor of CYP3A, does not contribute to the interaction between nifedipine and grapefruit juice

J Rashid, C McKinstry, A G Renwick, M Dirnhuber, D G Waller, C F George
British journal of clinical pharmacology 1993 36(5):460

Bibliography

PubMed
PMID 12959295
PubMed Central
PMC1364620
DOI
10.1111/j.1365-2125.1993.tb00396.x
Funding
Funding was not specified in the indexed record or the disclosure metadata available for this entry.
Competing interests
A competing-interest declaration was not available in the indexed record or the disclosure metadata used for this entry.

Study snapshot

DesignRandom-order human pharmacokinetic comparison
ModelHuman intervention research
Sample8 healthy volunteers
InterventionNifedipine 10 mg alone, with grapefruit juice, or with quercetin 400 mg
DurationSingle-dose comparisons
EndpointsExposure and pharmacokinetics

What the study showed, in plain terms

Published in 1993, this source examined safety, interactions and special populations. Design: Random-order human pharmacokinetic comparison. Sample/model: 8 healthy volunteers. The exposure or intervention was Nifedipine 10 mg alone, with grapefruit juice, or with quercetin 400 mg. Follow-up or treatment period: Single-dose comparisons.

Grapefruit juice increased nifedipine exposure; quercetin did not, although absorption timing was delayed.

Small acute substrate-specific study. Laboratory CYP3A inhibition did not predict the human exposure result, and other drug interactions remain possible.

Continue with Quercetin Data Center

For topic-level interpretation, read Quercetin Interactions: Medicines, Evidence and Precautions. This is a related guide; the citation panel separately identifies articles that directly cite this paper.

Key findings

  • Grapefruit juice increased nifedipine exposure; quercetin did not, although absorption timing was delayed.
  • The recorded outcome domains were Exposure and pharmacokinetics.
  • The result applies to the tested exposure: Nifedipine 10 mg alone, with grapefruit juice, or with quercetin 400 mg; Single-dose comparisons.

What this study can and cannot tell us

  • Small acute substrate-specific study. Laboratory CYP3A inhibition did not predict the human exposure result, and other drug interactions remain possible.
  • A change in blood exposure or a metabolic marker is not a demonstrated improvement in symptoms, disease events or lifespan. The tested formulation and co-administered medicines matter.
  • Source basis: Source check: accessible full text and indexed metadata. Missing method details, funding information or participant denominators are not inferred.

Related papers in the corpus

Tier 2
Phase 1 study of quercetin, a natural antioxidant for children and young adults with Fanconi anemia
Parinda A Mehta et al. · Blood advances · 2025
Tier 2
Randomised clinical trial to determine the safety of quercetin supplementation in patients with chronic obstructive pulmonary disease
Meilan K Han et al. · BMJ open respiratory research · 2020
Tier 2
Interaction study between antiplatelet agents, anticoagulants, diabetic therapy and a novel delivery form of quercetin
Antonella Riva et al. · Minerva cardioangiologica · 2019

Editorial review

Reviewed by the Biohack Blueprint research team

Last verified

Dr. Khaled Mahmoud, MBBChCritical Care Medicine, Longevity Science & Editorial Direction Dr. Amr Yasser, PhDCardiometabolic, Musculoskeletal, Gut & Bioavailability Dr. Abdulla Mostafa, PhDCellular Senescence, Neurological, Mitochondrial & Brain-Ageing Biology