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Pharmacology for Nurses

18.5 Calcium Channel Blockers

Pharmacology for Nurses18.5 Calcium Channel Blockers

Learning Outcomes

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
5–10 mg orally daily.
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.
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.
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.
(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.
Table 18.9 Drug Emphasis Table: Calcium Channel Blockers (source:

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 blocker

Mechanism 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.
To control hypertension
In the treatment of angina

Therapeutic Effects
Lowers blood pressure
Increases blood supply and oxygen to the heart
Drug Interactions

Food Interactions
No significant interactions
Adverse Effects
Peripheral edema
Skin rash
Muscle cramps
Erectile dysfunction

Aortic stenosis
Symptomatic hypotension
Myocardial infarction
Hepatic impairment
Table 18.10 Drug Prototype Table: Amlodipine (source:

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.

Unfolding Case Study

Part B

Read the following clinical scenario to answer the questions that follow. This case study is a follow-up to Case Study Part A.

Hahn Tran follows up with her health care provider one week later to get the results of her diagnostic studies. The health care provider diagnose her with hypertension stage 2 and starts her on enalapril, an ACE inhibitor. The nurse then teaches Hahn about this new drug.

Which instruction about enalapril will the nurse give Hahn?
  1. Take this medication with a meal.
  2. Do not take this medication if your heart rate is less than 60 beats/minute.
  3. Avoid salt substitutes that contain potassium while taking this medication.
  4. Avoid eating grapefruit while taking this medication.
Which nonpharmacologic treatment should the nurse anticipate the health care provider will prescribe for the client?
  1. Increase salt intake.
  2. Stop smoking.
  3. Walk 30–40 minutes twice weekly.
  4. Take naproxen sodium for headaches.

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