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, the same enzymes that break down verapamil before it reaches the bloodstream. Taking the two together sharply lowers verapamil's systemic exposure and can erase its therapeutic effect on blood pressure, heart rhythm, or migraine prevention.
amlodipine + calcium
In theory, supplemental calcium could slightly blunt the blood-pressure-lowering effect of calcium channel blockers such as amlodipine, but controlled human data do not show a meaningful effect. Drugs.com flags this as a minor, monitor-only interaction with weak clinical evidence.
amlodipine + grapefruit
Amlodipine is a CYP3A4 substrate, but unlike other dihydropyridine calcium channel blockers such as felodipine and 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, but the clinical signal at ordinary dietary intakes is small to negligible.
diltiazem + grapefruit
Grapefruit inhibits intestinal CYP3A4, modestly and unpredictably increasing systemic exposure to diltiazem.
dark chocolate + blood pressure medications
Cocoa flavanols in dark chocolate boost nitric-oxide-dependent vasodilation and modestly lower blood pressure. On top of antihypertensive medication the effect is additive and usually helpful, but in sensitive people it can occasionally nudge readings low enough to cause light-headedness.
celery juice + blood pressure medications
Celery contains phthalides (including 3-n-butylphthalide), nitrate, and potassium that relax blood vessels and have a mild blood-pressure-lowering effect demonstrated in a human trial of celery seed extract. Drinking celery juice regularly can add to the effect of antihypertensive drugs such as ACE inhibitors, ARBs, calcium channel blockers, and diuretics, potentially pushing blood pressure lower than intended.