Calcium Channel Blockers

Two members, two jobs. A non-dihydropyridine (IV diltiazem, verapamil) is the rate-control substitute when the beta-blocker is contraindicated or not tolerated (2a) — severe asthma or bronchospasm, and cocaine-induced dissection. A dihydropyridine (nicardipine, clevidipine) is an add-on vasodilator for pressure that stays above target after rate control — never the opening drug, for the same reflex-tachycardia reason. Long term, avoid CCBs in Marfan syndrome unless needed for BP control.

Only the non-dihydropyridines (verapamil, diltiazem) are HCM options, as an alternative to a beta-blocker; evidence does not support combining the two. The dihydropyridine vasodilators amlodipine and nifedipine are on the HCM avoid list because they unload the ventricle and worsen obstruction.

A cause of leg edema to consider, not a treatment. StatPearls lists "Medication adverse effects (eg, calcium channel blockers, NSAIDs, and oral hypoglycemic agents)" in the differential of leg swelling.

The other first-line rate-control arm in afib and an option for recurrent SVT. The non-dihydropyridines are AV-nodal blockers — which is exactly why they also appear among the causes of bradycardia and AV block; same rule: check the rate before giving.

Dihydropyridine CCBs are first-line, reducing all cardiovascular events comparably to thiazides except heart failure. The class also supplies the crisis workhorses: IV nicardipine and clevidipine are rapid-acting, titratable emergency agents, with nicardipine favored in acute stroke.

Prevention: verapamil (and flunarizine), suited to women of childbearing age and Raynaud phenomenon. Verapamil is the usual first choice for preventing cluster periods — with regular ECGs.

An add-on or alternative. "Calcium channel blockers, such as amlodipine and nifedipine, can serve as alternative or add-on agents to effectively control hypertension in the preoperative period," and a short-acting one such as nicardipine can control hypertension during surgery.

Nifedipine "is often used for tocolysis, especially after 30 to 32 weeks of EGA." "Calcium channel blockers specifically work on T-type calcium channels by inhibiting the entry of calcium into the uterine smooth muscle," and "The lack of free calcium directly affects the ability of the calcium-calmodulin activation of myosin light chain kinases" — no calcium, no cross-bridge cycling, no contraction. The preterm-labor source notes nifedipine "has a better safety profile than other tocolytic medications." Recent literature suggests it offers "better neonatal outcomes and fewer side effects" than the alternatives. The nursing consequence is a single parameter: maternal hypotension. Maternal adverse effects are flushing, headache, dizziness, nausea and hypotension; "Studies have shown no fetal risks with nifedipine use for the management of preterm labor"; and "Women who have documented hypotension and other cardiac conditions should use nifedipine with great caution" — so blood pressure is what gets monitored around each dose. And the magnesium interaction applies here, since these two drugs are the pairing the warning is about. Calcium channel blocker pharmacology otherwise belongs to the class page.

Only for vasoreactivity-positive idiopathic, heritable or drug-induced PAH — then high-dose CCBs can be first-line (amlodipine or nifedipine if the heart rate is slow, diltiazem if fast). Watch for hypotension and edema. In group 2 they may treat the left-heart cause. They are not a general PH drug.

[RAY] First-line drug when warmth and avoidance are not enough. "Long-acting dihydropyridine calcium channel blockers (DHP CCBs) are the first-line pharmacologic treatment for Raynaud phenomenon. Amlodipine and nifedipine are typically preferred" (StatPearls). This is off-label: "there are no medications approved by the U.S. Food and Drug Administration for Raynaud’s phenomenon" (NIAMS). Watch blood pressure; expect "flushing, peripheral edema, dizziness, and headache"; avoid grapefruit; "Abrupt discontinuance of the drug after prolonged use may lead to rebound hypertension or angina."

[Raynaud’s] First-line. "Long-acting dihydropyridine calcium channel blockers (DHP CCBs) are the first-line pharmacologic treatment for Raynaud phenomenon." NHS: "you may be offered nifedipine" — some take it daily, others "only use it to prevent Raynaud’s, for example, during cold weather." Watch BP, "particularly in patients with low baseline blood pressure," and "peripheral edema, palpitations, reflex tachycardia, dizziness, and headache." Scope: first-line for Raynaud’s only — for SSc-PAH, "Calcium channel blockers are generally ineffective." In renal crisis, a dihydropyridine CCB can be added if BP is not controlled on a maximal ACE inhibitor.

[NIM] Nimodipine — enteral only, 21 days. Indicated "for the improvement of neurological outcome by reducing the incidence and severity of ischemic deficits" after aneurysmal SAH, Hunt and Hess grades I–V. Label: "The recommended oral dose is 60 mg (two 30 mg capsules) every 4 hours for 21 consecutive days," starting "as soon as possible within 96 hours of the onset of subarachnoid hemorrhage" (reduced in cirrhosis). Boxed warning: "DO NOT ADMINISTER NIMODIPINE INTRAVENOUSLY OR BY OTHER PARENTERAL ROUTES." Give 1 hour before or 2 hours after meals; avoid grapefruit juice. "Blood pressure should be carefully monitored" — hypotension is the most frequent adverse effect; a dose reduction for hypotension is the prescriber’s decision. Strong CYP3A4 inducers (carbamazepine, phenobarbital, phenytoin, rifampin, St. John’s wort) "should generally be avoided." StatPearls: nimodipine reduces DCI and improves outcome "without affecting vasospasm." Before securing, StatPearls names nicardipine and clevidipine infusions (and intermittent labetalol or hydralazine) for BP control.

Interaction — "calcium channel blockers such as diltiazem and verapamil" increase tacrolimus levels.

Slow heart rate & lower BP by blocking β-adrenergic receptors. Watch for bradycardia.

Lower BP by blocking angiotensin conversion. Classic dry cough & angioedema risk.

Lower LDL cholesterol via HMG-CoA reductase inhibition. Monitor for myopathy.

Injectable antibodies that protect the liver’s LDL receptors, cutting LDL cholesterol by about half and lowering cardiovascular events. Given subcutaneously every 2–4 weeks.

PPAR-α agonists that mainly lower triglycerides — used with diet for severe hypertriglyceridemia — with muscle, gallbladder, liver and kidney risks, highest for gemfibrozil combined with a statin.

Non-absorbed resins that trap bile acids in the gut, forcing the liver to use cholesterol and pull LDL from the blood. Constipation, drug binding and rising triglycerides are the issues to manage.