Grapefruit juice with felodipine,
does it really help with A clinically important increase in felodipine exposure?
research showsThe grade is C. Randomized crossover studies in healthy volunteers found that grapefruit juice with felodipine 10 mg increased AUC roughly two- to threefold, and a 14-day study found greater heart-rate and diastolic-pressure effects plus more vasodilation-related adverse events. This is a real food-drug restriction, but evidence centers on small pharmacokinetic and short-term hemodynamic studies, giving C with 50 points.
ads claimIntestinal CYP3A4 inhibition is a physiological fact, and the human two- to threefold felodipine exposure increase is real. That does not mean every user will have a major clinical event.
Useful facts when choosing a product
- Studies used felodipine ER 10 mg with about 200-250 mL grapefruit juice.
- Median AUC was 110 nmol·h/L with regular grapefruit juice, 54 with orange juice, and 48 with furanocoumarin-depleted juice.
- Current labeling states that grapefruit juice can more than double felodipine AUC and peak concentration.
Chamgap Semantic Classification Code
Candidate index · review held
F.felodipine-extended-release-taken-with-about-grapefruit-juice.food.a-clinically-important-increase-in-felodipine-exposure.increase.UNKFoods and beverages > Felodipine extended-release taken with about grapefruit juice > Food consumption > A clinically important increase in felodipine exposure > Increase claim > Unknown
An automated migration candidate, not an issued permanent code; exact claim scope remains under review. This machine-generated migration candidate helps retrieval but is not a permanent assignment. The original verdict ID and URL remain authoritative.
What the research actually shows
Bailey et al. used a randomized four-way crossover comparison of felodipine ER 10 mg with water, 250 mL juice, segments, or peel-region extract and reported about threefold AUC with all grapefruit conditions. In 18 participants, Paine et al. found median AUC 110 nmol·h/L with regular juice, 54 with orange juice, and 48 after about 99% furanocoumarin removal. A 12-man 14-day crossover study reported AUC +73% on day one and +57% on day 14, with greater heart-rate and diastolic-pressure effects and more vasodilation-related adverse events. Funding could not be confirmed across all trials, so independent replication was not assigned.
Why this is classified as C (50)
The exposure increase is large and short-term hemodynamic and adverse-event intensification was observed, but the evidence remains small and surrogate-centered, giving C with 50 points.
Counterpoint. A gap of only a few hours may not avoid the interaction; effects on AUC persisted at ten hours and peak concentration changes were reported at 24 hours.
Rejudgment record. Cross-check applied — Repeated two- to threefold pharmacokinetic exposure increases in small randomized crossover studies, with short-term hemodynamic and adverse-event intensification
| Endpoint | S | Surrogate marker - laboratory or imaging measures |
| Replication | R1 | Single confirmatory trial |
| Independence | I1 | Mixed funding sources |
| Effect size | E+ | Meets the clinically important threshold |
Stored derived and displayed grades match; this is not a current recalculation or validity check (C).
Sub-claim grades by effect
This ingredient is marketed for several effects. A single overall grade blends strong and weak claims together, so each effect is graded separately here. The overall grade reflects the strongest disconfirming or core claim.
| Effect (sub-claim) | Grade | Basis |
|---|---|---|
| Approximately two- to threefold higher felodipine AUC | C | Multiple crossover studies confirmed a large increase. |
| Major clinical events in every user | ? | No direct comparison measured events such as hospitalization or syncope. |
Cross-check — AI research and Codex final gate
Evidence Table
| Study | Design | Sample | Funding | Endpoint | Result | Weight |
|---|---|---|---|---|---|---|
| Bailey et al. 2000 | Randomized four-way crossover pharmacokinetic study | Analyzed number not confirmed in the public abstract | Indexed as non-US government support; specific source not confirmed | Felodipine AUC and peak concentration | Juice, segments, and peel-region extract each produced about threefold mean AUC versus water | Pivotal pharmacokinetic evidence |
| Paine et al. 2006 | Randomized crossover pharmacokinetic study | 18 participants | Not confirmed in the public material reviewed | AUC after furanocoumarin removal | Median AUC 110 with regular grapefruit, 54 with orange, and 48 nmol·h/L with depleted juice | Active-constituent and replication support |
| Lundahl et al. 1998 | 14-day randomized crossover coadministration trial | 12 participants | Not confirmed in the public material reviewed | AUC, blood pressure, heart rate, and adverse events | AUC +73% on day one and +57% on day 14, with greater hemodynamic effects and vasodilation-related adverse events | Short-term clinical-link evidence |
Receipt — 4 References
All 4 cited sources were verified for existence at the original page (as of 2026-08-04).
Final verification and publication gate: Codex · Evidence date: 2026-08-04 · Corrections: none
Cite this verdict
[Chamgap] Grapefruit juice with felodipine x increased drug exposure — Evidence Grade C·50. 4 cited sources checked. Source: https://chamgap.com/en/verdicts/heart/grapefruit-juice-felodipine-exposure-interaction/ · CC BY 4.0CC BY 4.0 — free to use with attribution; do not distort grades, numbers, or verdict meaning.
What this document does and does not do
Chamgap is an information source. It reports what research has and has not confirmed; it does not tell readers what to take or buy. That decision belongs to readers and, when needed, medical or legal professionals. This verdict reflects literature available up to the search date and may change as new research appears. Nothing here is medical advice.