Can patients taking amlodipine (calcium channel blocker) for hypertension or coronary artery disease consume grape juice?

Grape Juice and Amlodipine: No Interaction Exists

Patients taking amlodipine can safely consume grape juice without concern for drug interactions. According to the FDA drug label, grapefruit juice—not grape juice—has no impact on amlodipine exposure, and this distinction is critical 1.

The Grapefruit Confusion

The common misconception likely stems from confusion between grape juice and grapefruit juice:

• Grapefruit juice is well-known for inhibiting CYP3A4 enzymes in the intestinal wall, which can dramatically increase blood levels of many medications metabolized by this pathway 1
• Grape juice does not contain the furanocoumarins (bergamottin and 6',7'-dihydroxybergamottin) that are responsible for CYP3A4 inhibition seen with grapefruit 1

FDA Evidence on Amlodipine Interactions

The FDA drug label explicitly states that grapefruit juice has no impact on the exposure to amlodipine 1. This is notable because:

• Amlodipine is metabolized extensively (about 90%) via hepatic CYP3A4 enzymes 1
• Despite this CYP3A4 metabolism, grapefruit juice does not significantly alter amlodipine pharmacokinetics 1
• Other CYP3A4 inhibitors like diltiazem (180 mg daily) can increase amlodipine exposure by 60%, and strong inhibitors like itraconazole or clarithromycin may increase it further 1

Clinical Implications

There is no need to counsel patients taking amlodipine to avoid grape juice. The restriction applies only to grapefruit juice with certain medications, and amlodipine is not even among those significantly affected 1.

Common Pitfall to Avoid

• Do not conflate grape juice with grapefruit juice when counseling patients on dietary restrictions with calcium channel blockers 1
• Even for grapefruit juice specifically, amlodipine shows no clinically significant interaction, unlike some other dihydropyridine calcium channel blockers 1

Substances That Actually Affect Amlodipine

Patients should be aware of medications that genuinely increase amlodipine levels:

• Strong CYP3A4 inhibitors (itraconazole, clarithromycin) may increase amlodipine plasma concentrations 1
• Diltiazem co-administration increases amlodipine systemic exposure by 60% 1
• Erythromycin does not significantly change amlodipine exposure 1

Bottom line: Grape juice consumption is safe with amlodipine therapy, and even grapefruit juice does not significantly interact with this particular calcium channel blocker 1.