calcium channel blocker
6 interactions related to calcium channel blocker
verapamil + st. john's wort
St. John's wort is a potent inducer of intestinal CYP3A4 and P-glycoprotein. In a controlled study, two weeks of St. John's wort reduced the AUC of R- and S-verapamil by roughly 78-80%, dramatically lowering systemic drug exposure and likely therapeutic effect.
amlodipine + calcium
Theoretically, high doses of supplemental calcium could blunt the vasodilatory effect of calcium channel blockers such as amlodipine, but controlled human data are limited. Drugs.com flags this as a minor monitor-only interaction with weak clinical evidence.
amlodipine + grapefruit
Amlodipine is a CYP3A4 substrate, but unlike other dihydropyridines (felodipine, nisoldipine), its high oral bioavailability and slow elimination mean grapefruit juice does not meaningfully alter its pharmacokinetics in controlled trials. Some product labels and consumer references still list a theoretical interaction.
diltiazem + grapefruit
Grapefruit juice inhibits intestinal CYP3A4 and increases diltiazem exposure (AUC) by roughly 20% in healthy volunteers, with high inter-individual variability. The increase can amplify the drug's negative chronotropic and hypotensive effects.
dark chocolate + blood pressure medications
Dark chocolate flavanols improve nitric-oxide-dependent vasodilation and modestly lower systolic and diastolic blood pressure (typically 2–3 mmHg). Combined with antihypertensives, this can additively lower blood pressure, occasionally producing symptoms of hypotension such as dizziness in sensitive patients.
celery juice + blood pressure medications
Celery contains phthalides (including 3-n-butylphthalide), nitrate, and other constituents that relax vascular smooth muscle and have demonstrated blood pressure lowering effects in animal and small human studies. Large daily celery juice intake can add to the effect of antihypertensive drugs, including ACE inhibitors, calcium channel blockers, and diuretics.