Quiz 30: Pharmacotherapy With Calcium Channel Blockers
Mrs. M was prescribed amlodipine. The drug is expensive and she could not afford its price. Her health insurance does not cover prescription drug costs. She feels she is fine and does not need the medicine, considering its cost. As she feels fine she questions as to why she should take amlodipine daily. After all, she thinks the drug is very expensive and also her health insurance does not cover drug. Although she feels fine, nurse justifies that amlodipine are prescribed to treat the hypertension (HTN) by maintaining the blood pressure. If the condition is left untreated, it may lead to severe complications in future. Organs like heart, kidney, and liver may also become affected if left untreated. Hence, Mrs. M was instructed undergo the medication to overcome hypertension.
In the cardiac muscles when the beta-adrenergic receptors are activated, the calcium channels are opened. As a result the heart rate and contractility is increased. Blocking cardiac beta adrenergic receptors with adrenergic antagonists will prevent the opening of calcium channels. Thus the cardiac effects, indications, and adverse effects of beta-adrenergic blockers and calcium channel blockers are similar. Beta blockers decrease blood pressure and decrease cardiac contractility. Beta-adrenergic antagonists such as propranolol and calcium channel blockers both have additive effects. Both the drugs are known to decrease blood pressure and decrease cardiac contractility. As a result of drug interactions hypotension (decreased blood pressure) and bradycardia (decreased heart rate) are expected. Calcium channel blockers are known to treat hypertension. They cause vasodilatation, decreases cardiac contractility, and decreases cardiac output as a result decrease in blood pressure. Epinephrine is an autonomic drug. It causes vasoconstriction, increases cardiac output, and increases blood pressure. Hence calcium channel blockers and epinephrine are antagonistic to each other in indications, effects and side effects. So no drug-drug interactions can be expected between calcium channel blockers and epinephrine.
Mrs. E's blood pressure was 150/92 mmHg and it was considered to be an elevated level. She should undergo medication that includes calcium channel blockers for the treatment of hypertension (HTN). The calcium channel blockers (CCBs) are also known as calcium channel antagonists that do not block the channel openings; instead, they prevent enough Ca 2+ form entering the muscle cell. Several research studies also reported that the calcium and magnesium supplements might help to maintain a normal blood pressure or lower high blood pressure. The calcium channel blockers have their action on vascular smooth muscle, cardiac muscle, and the conduction system in the heart. The calcium ions play a vital role in the contraction of smooth muscle cells. Due to the contraction of arterioles the flow of blood must be in systemic circulation (controls peripheral resistance). Therefore, the calcium channel blockers contract the peripheral arterioles to decrease the blood pressure. Example: Dihydropyridines are the largest class of calcium channel blockers which includes amlopidine. About 5-10 mg of amlopidine once daily is to be in taken by the patient for the treatment of hypertension.