What It Is:
Diltiazem is a calcium channel blocker. It works by relaxing the muscles of your heart and blood vessels. Calcium channel blockers reduce the speed at which calcium moves into the heart muscle, blood vessels, and cells in the heart that control your heart rate.
The drugs increase the diameter of blood vessels, reduce the force of contraction of the heart, and slow the heart rate, all of which helps keep your heart from having to work as hard.
Mechanism of Action:
Calcium channel blockers are drugs that block the entry of calcium into the muscle cells of the heart and arteries.
• The entry of calcium is critical for the conduction of the electrical signal that passes from muscle cell to muscle cell of the heart, and signals the cells to contract.
• The entry of calcium is also necessary in order for the muscle cells to contract and pump blood.
• In the arteries, the entry of calcium into muscle cells constricts the arteries and thereby dilates (widens) the arteries.
• Thus, by blocking the entry of calcium, calcium channel blockers reduce electrical conduction within the heart, decrease the force of contraction of the muscle cells, and dilate arteries.
• Dilation of the arteries reduces blood pressure and thereby the effort the heart must exert to pump blood.
• Combined with decreases in the force of contraction, this leads to a reduced requirement for oxygen by the heart.
• Dilation of the arteries provides more oxygen-carrying blood to the heart.
• The combination of reduced demand for oxygen and increased delivery of oxygen prevents angina or heart pain (Angina occurs when the heart is not getting enough oxygen relative to the amount of work it is doing).
• In addition, calcium channel blockers slow electrical conduction through the heart and thereby correct abnormal rapid heartbeats.
• Calcium channel blockers comprise three chemical groups, all of which bind to the L-type Ca++ channel responsible for the excitation. They are high voltage, located in skeletal muscle, bone osteoblasts, ventricular myocytes, dendrites & dendritic spines of cortical neurons. L-type calcium channels function in smooth muscle & cardiac muscle contraction and are responsible for prolonged action potential in cardiac muscle.
What the Drug is Treating:
Calcium channel blockers, calcium channel antagonists, or calcium antagonists are several medications that disrupt the movement of calcium through calcium channels. The medications reduce blood pressure by helping blood vessels to relax.
Calcium channel blockers are a class of drugs prescribed for high blood pressure. In addition to high blood pressure (hypertension), calcium channel blockers are also prescribed to treat:
• Angina (chest pain)
• Arrhythmia (irregular heartbeat)
Drug Interactions:
Calcium channel blockers may interact with other medications, so always tell your doctor about every medication, recreational drug, vitamin, and supplement — whether over-the-counter (OTC) or prescription — that you are taking.
Calcium channel blockers should always be taken with a meal or a glass of milk to protect the stomach. You should not, however, take calcium channel blockers with grapefruit juice or grapefruit.
Some of the drugs that are likely to interact with calcium channel blockers include:
• Other high blood pressure medications, including ACE (angiotensin-converting enzyme) inhibitors or beta blockers
• Diuretics (water pills)
• Some eye medications
• Large amounts of vitamin D or calcium supplements
• Drugs used to treat arrhythmia
• Digitalis, also called digitoxin (Digoxin)
• Drugs that contain cortisone, or any corticosteroids
Remember to take calcium channel blockers exactly as your doctor or pharmacist recommends. This means not crushing, chopping, or dissolving these medications unless you’re told it’s okay — especially if you’re taking a medication that ends in XL or XR, which means extended release.
Contraindications:
• In congestive heart failure, patients with reduced ventricular function may not be able to counteract the inotropic and chronotropic effects of diltiazem, the result being an even higher compromise of function.
• With SA node or AV conduction disturbances, the use of diltiazem should be avoided in patients with SA or AV nodal abnormalities, because of its negative chronotropic and dromotropic effects.
• Low blood pressure patients, with systolic blood pressures below 90 mm Hg, should not be treated with diltiazem.
• Diltiazem may paradoxically increase ventricular rate in patients with Wolff-Parkinson-White syndrome because of accessory conduction pathways.
Side-Effects:
It’s also important to avoid drinking alcohol when taking calcium channel blockers. Alcohol, combined with a calcium channel blocker, can cause severe side-effects and may also affect the way the medication works.
Side effects from taking calcium channel blockers are usually fairly mild, but may include:
¥ Weight gain
¥ Swelling in the lower legs, feet, or ankles
¥ Feeling dizzy
¥ An increase in appetite
¥ Constipation
¥ Feeling tired or drowsy
¥ A heartbeat that feels rapid, slow, or irregular
¥ Coughing, wheezing, or problems with breathing or swallowing
¥ Nausea or stomach discomfort
¥ Numbness or a tingling sensation in the feet or hands
Calcium channel blockers are generally safe, but like any medication, need to be taken properly and with care. To lessen the chance of interactions, always tell your doctor about other medications you’re taking.
And remember that you don’t have to deal with side effects: Talk to your doctor about them. Chances are that a slight adjustment in the dosage or the way you take your medication will help you feel better while allowing you to get the treatment you need.
Dose:
PO: (Adults) 30–120 mg 3–4 times daily or 60–120 mg twice daily as SR capsules or 180–240 mg once daily as CD or XR capsules or LA tablets (up to 360 mg/day); Concurrent simvastatin therapy–Diltiazem dose should not exceed 240 mg/day and simvastatin dose should not exceed 10 mg/day.
IV: (Adults) 0.25 mg/kg; may repeat in 15 min with a dose of 0.35 mg/kg. May follow with continuous infusion at 10 mg/hr (range 5–15 mg/hr) for up to 24 hr.
Teaching Plan:
You have been prescribed Diltiazem which is a calcium channel blocker. It works by relaxing the muscles of your heart and blood vessels. Calcium channel blockers reduce the speed at which calcium moves into heart muscle, blood vessels, and cells in the heart that control your heart rate.
The drugs increase the diameter of blood vessels, reduce the force of contraction of the heart, and slow the heart rate, all of which helps keep your heart from having to work as hard. This is a list of considerations and protocols to be aware of while taking a calcium channel blocker.
• Advise patient to take medication as directed at the same time each day, even if they are feeling well.
• Take missed doses as soon as possible unless almost time for next dose; do not double doses. May need to be discontinued gradually.
• Advise patient to avoid large amounts (6–8 glasses of grapefruit juice/day) during therapy.
• Instruct patient on correct technique for monitoring pulse. Instruct patient to contact health care professional if heart rate is <50 bpm.
• Caution patient to change positions slowly to minimize orthostatic hypotension.
• May cause drowsiness or dizziness. Advise patient to avoid driving or other activities requiring alertness until response to the medication is known.
• Instruct patient on importance of maintaining good dental hygiene and seeing dentist frequently for teeth cleaning to prevent tenderness, bleeding, and gingival hyperplasia (gum enlargement).
• of all Rx or OTC medications, vitamins, or herbal products being taken and to avoid concurrent use of alcohol or OTC medications and herbal products, especially NSAIDs and cold preparations, without consulting health care professional.
• Advise patient to notify health care professional if rash, irregular heartbeats, dyspnea, swelling of hands and feet, pronounced dizziness, nausea, constipation, or hypotension occurs or if headache is severe or persistent.
• Caution patient to wear protective clothing and use sunscreen to prevent photosensitivity reactions. Advise female patient to notify health care professional if pregnancy is planned or suspected or if breast feeding.
• Angina: Instruct patient on concurrent nitrate or beta-blocker therapy to continue taking both medications as directed and to use SL nitroglycerin as needed for anginal attacks.
• Advise patient to contact health care professional if chest pain does not improve, worsens after therapy, or occurs with diaphoresis; if shortness of breath occurs; or if severe, persistent headache occurs.
• Caution patient to discuss exercise restrictions with health care professional before exertion.
• Hypertension: Encourage patient to comply with other interventions for hypertension (weight reduction, low-sodium diet, smoking cessation, moderation of alcohol consumption, regular exercise, and stress management). Medication controls but does not cure hypertension.
• Instruct patient and family in proper technique for monitoring BP. Advise patient to take BP weekly and to report significant changes to health care professional.