Calcium-channel blockers: Nursing pharmacology

Calcium channel blockers are medications that are primarily used to treat cardiac arrhythmias, hypertension and angina pectoris.

Calcium channel blockers are used to a lesser extent for prophylaxis of migraines and for symptomatic treatment of Raynauds phenomenon, which is caused by reduced blood flow in tiny peripheral vessels.

Finally, calcium channel blockers also relax uterine smooth muscle, which is useful to prevent premature uterine contractions and this can help delay preterm labor.

Now, calcium channel blockers can be administered orally or intravenously and are divided into two main groups. Dihydropyridines and non dihydropyridines.

Dihydropyridines include amLODIPine, niCARdipine, nifedipine, felodipine and Clevidipine, which have a more potent action on the blood vessels, specifically the arterioles than the heart as a result.

They are preferred to treat hypertension. Another dihydropyridine is niMODipine, which has the added benefit of being able to cross over the blood brain barrier.

So it can be used to prevent or treat cerebral vasospasm caused by an aneurysmal subarachnoid hemorrhage. On the other hand, non dihydropyridines include verapamil and dilTIAZem, which have a more potent action on the heart than the blood vessels.

Verapamil is highly selective for cardiac calcium channels and thus is mainly used to treat angina, pectoris and arrhythmias.

DilTIAZem is equally good at blocking both cardiac and vascular calcium channels. So its effective in hypertension and arrhythmias.

Now, once administered calcium channel blockers block voltage gated calcium channels and they act by decreasing the amount of calcium entering the cell.

Normally, calcium is required for the contraction of both the cardiac muscles and the vascular smooth muscles. So the decreased calcium reduces the muscles ability to contract, ultimately relaxing them.

Now, calcium channel blockers relax vascular particularly arterial smooth muscles, which helps reduce the BP and peripheral vascular resistance or the afterload, which is the pressure that the heart must work against to eject the blood.

At the same time in the heart, calcium channel blockers relax the coronary vessels which improves the oxygen delivery to the heart and they also reduce the force of contraction of the cardiac muscles which reduces the oxygen demand of the heart.

Additionally, calcium channel blockers prevent the depolarization of cardiac pacemaker cells in the sa and AV nodes which are responsible for generating and maintaining the heart rate.

This way, these medications reduce the firing and conduction of the impulses through these nodes eventually decreasing the heart rate.

Now, the vasodilatory action of calcium channel blockers may also lead to some side effects including headache, dizziness, flushing of the skin, peripheral edema and hypotension which is more common with dihydropyridines.

Moreover hypotension can trigger reflex tachycardia in order to maintain adequate tissue perfusion. Finally, dihydropyridines can also cause gingival hyperplasia.

The cause of which is still unclear. On the other hand, non dihydropyridines decrease the heart rate and contractility.

So they can cause additional side effects like bradycardia, constipation and hyperprolactinemia. Now, due to their depressive action on the heart, non dihydropyridines and to a lesser extent, dihydropyridines are contraindicated in clients with preexisting, bradycardia, heart block and heart failure.

In addition, calcium channel blockers should be used cautiously in clients with hepatic or renal disease as well as when combined with digoxin, which is an anti arrhythmic medication.

As clients can develop digoxin toxicity by reducing its action and elimination. Finally, clients on calcium channel blockers must avoid consuming grapefruit as their interaction can result in toxicity.

Now, if your client is prescribed a calcium channel blocker, be sure to obtain their baseline heart rate and BP and review their lab results including CBC sodium, potassium, creatinine bun liver function tests and urinalysis as well as their electrocardiogram or ECG.

If your client is taking a calcium channel blocker for angina pectoris, remember to ask them about the frequency and severity of their anginal symptoms.

Be sure your client understands how the medication helps control their symptoms and instruct them to take their medication exactly as instructed and to not stop taking it abruptly, let them know that they can take their medication with or without food.

And that extended release tablets should not be divided, crushed or chewed stress. The importance of avoiding grapefruit and grapefruit juice, which can increase the blood level of their medication and advise them to limit caffeine consumption as well.

Since it can increase BP and heart rate, then teach your client how to take their pulse and BP and to contact their health care provider.

If they experience hypotension or bradycardia, if their medication is prescribed for angina, stress the importance of seeking medical assistance immediately if they experience angina that is not relieved by rest or medication, finally reinforce cardiovascular health promotion by teaching your client about lifestyle modifications such as maintaining a healthy weight, smoking, cessation, reducing their intake of sodium and alcohol and increasing physical activity.

Next, talk to your client about how to manage the common side effects of calcium channel blockers. Let them know that they may experience dizziness, hypotension and reflex tachycardia and that they should change positions slowly to prevent falls.

If your client develops peripheral edema in the ankles and feet, encourage them to elevate their legs for a few hours each day.

Remind your client how increasing their daily intake of fluid and fiber can help reduce the risk of constipation. Also stress the importance of good dental hygiene to prevent gingival hyperplasia.

Lastly prompt your client to contact their health care provider. If any of these adverse effects are persistent or become bothersome during treatment, monitor your clients BP, heart rate and anginal symptoms for therapeutic effects of the medication.

Finally continue to monitor for side effects and report any changes in the clients condition to the health care provider.

All right, as a quick recap, calcium channel blockers are medications that are used to treat cardiac arrhythmias, hypertension, angina pectoris and other conditions.

These medications work by blocking calcium channels in the vascular smooth muscles and cardiac muscles which in turn helps them to relax.

Non dihydropyridines have a more potent action on the heart than dihydropyridines. So they are used more often to treat arrhythmias and angina pectoris.

While dihydropyridines exert their effects primarily on the blood vessels. So they are more often used to treat hypertension nursing considerations for calcium channel blockers center around completing a thorough baseline assessment, providing client education for safe self administration and dealing with side effects such as hypotension, bradycardia and constipation, promoting cardiovascular health and evaluating the therapeutic