4.2.5 Calcium Channel Blockers
Calcium Channel Blockers
From Pharmacology for Nurses, OpenStax Chapter 18
Learning Objectives
By the end of this section, you should be able to:
- 18.5.1 Identify the characteristics of the calcium channel blocker drugs used to treat hypertension and angina.
- 18.5.2 Explain the indications, actions, adverse reactions, and interactions of the calcium channel blocker drugs used to treat hypertension and angina.
- 18.5.3 Describe nursing implications of calcium channel blocker drugs used to treat hypertension and angina.
- 18.5.4 Explain the client education related to calcium channel blocker drugs used to treat hypertension and angina.
Introduction and Use
Calcium channel blockers are a classification of drug that blocks calcium from entering cells by binding to long-acting voltage-gated calcium channels in the heart, smooth muscle, and pancreas. Calcium causes vasoconstriction. Calcium channel blockers inhibit calcium and allow for vasodilation, thereby causing the heart rate to slow and blood pressure to lower. Calcium channel blockers are commonly used to treat hypertension, angina, and arrhythmias.
Calcium channel blockers are classified as dihydropyridines or nondihydropyridines. Dihydropyridines are peripheral vasodilators that lower blood pressure and heart rate; they are used to treat post-intracranial hemorrhage, vasospasm, and migraines. In addition to their action on the peripheral vasculature, nondihydropyridines inhibit the sinoatrial and AV nodes, slowing cardiac conduction and heart rate and decreasing oxygen demand.
Calcium channel blockers may be used alone or in combination with other drugs. They are highly protein bound, which increases the volume of distribution within the body. Calcium channel blockers are available in long- and short-acting formulas.
Special Considerations
Calcium Channel Blockers
Calcium channel blockers are among the most effective antihypertensive classifications of drugs for use in non-Hispanic Black adults.
(Source: Abrahamowicz et al., 2023)
Safety Alert
Calcium Channel Blockers
Abrupt discontinuation of calcium channel blockers may cause chest pain.
Table 18.9 lists common calcium channel blockers and typical routes and dosing for adult clients.
| Drug | Routes and Dosage Ranges |
|---|---|
| Amlodipine (Norvasc) |
5–10 mg orally daily. |
| Diltiazem (Cardizem) |
Initial dosage: 30 mg orally 4 times daily, before meals and at bedtime. Increase dosage gradually (given in divided doses 3–4 times daily) at 1- to 2-day intervals until optimum response is obtained. Average optimum dosage: 180–360 mg daily. |
| Nicardipine (Cardene) |
Immediate release: 20–40 mg orally 3 times daily. Sustained release: 30–60 mg daily; maximum dose 120 mg daily. Intravenous (IV) infusion: 5–15 mg hourly. |
| Nifedipine (Procardia) |
Immediate release: Starting dose 10 mg orally 3 times daily. The usual effective dose range is 10–20 mg 3 times daily. Doses above 120 mg daily are rarely necessary. More than 180 mg daily is not recommended. Sustained release: 30–60 mg orally daily; maximum dose 120 mg daily. |
| Verapamil (Calan SR, Verelan) |
Immediate release: 40–120 mg 3 times daily. Sustained release: 180–240 mg daily. IV: Follow manufacturer’s instructions and health care provider’s orders. |
Adverse Effects and Contraindications
Adverse effects of calcium channel blockers include dizziness, constipation, palpitations, fatigue, flushing, nausea, rash, headache, and swelling in the legs and feet. Serious side effects include thrombocytopenia, hypotension, and hyperglycemia. Clients with a hypersensitivity to calcium channel blockers or their components should not use this classification of drug. Other contraindications include sick sinus syndrome (except in clients with an artificial pacemaker), severe hypotension, a history of myocardial infarction, or a history of pulmonary congestion.
Table 18.10 is a drug prototype table for calcium channel blockers featuring amlodipine. It lists drug class, mechanism of action, adult dosage, indications, therapeutic effects, drug and food interactions, adverse effects, and contraindications.
| Drug Class Calcium channel blockerMechanism of Action Inhibits the influx of calcium ions into vascular smooth muscle and cardiac muscle, thereby decreasing peripheral vascular resistance and reducing blood pressure |
Drug Dosage 5–10 mg orally daily. |
| Indications To control hypertension In the treatment of anginaTherapeutic Effects Lowers blood pressure Increases blood supply and oxygen to the heart |
Drug Interactions Simvastatin Clarithromycin RitonavirFood Interactions No significant interactions |
| Adverse Effects Peripheral edema Headache Fatigue Palpitations Hypotension Dizziness Nausea Flushing Pruritus Skin rash Muscle cramps Erectile dysfunction |
Contraindications HypersensitivityCaution: Aortic stenosis Symptomatic hypotension Angina Myocardial infarction Hepatic impairment Pregnancy Breastfeeding |
Nursing Implications
The nurse should do the following for clients who are taking calcium channel blockers:
- Monitor the client for interactions because many medications and herbal supplements, such as St. John’s wort, interact with calcium channel blockers. Grapefruit juice also can affect the action of certain calcium channel blockers.
- Assess and monitor the client for adverse effects and contraindications.
- Provide client teaching regarding the drug and when to call the health care provider. See below for client teaching guidelines.
Client Teaching Guidelines
The client taking a calcium channel blocker should:
- Report side effects such as severe headaches, dizziness, lightheadedness, flushing, nausea, and leg swelling to their health care provider.
- Take this medication with food to avoid GI upset, nausea, and vomiting.
FDA Black Box Warning
Calcium Channel Blockers
Immediate release nifedipine, a potent calcium blocker, may increase the risk of myocardial infarction, stroke, and arrhythmias.
Next- 4.2.6 Diuretics
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