calcium channel blocker (CCB ) is widely used in the treatment of hypertension, angina pectoris, arrhythmia and other diseases. Calcium channel blockers can be used alone or in combination with other drugs. Clinical selection depends on the clinical characteristics of the patient and the therapeutic properties of the drug. This article introduces the therapeutic properties of different CBB drugs, and how to use them correctlynon-clinical. Dihydropyridine CCB.
< span>1. Different drug structures have different therapeutic properties
Although all calcium channel blockers inhibit L-type calcium channels on cells, According to the main physiological effects, it can be divided into two categories: dihydropyridines are mainly vasodilators, and generally have limited cardiac chronotropic and inotropic effects;Non-dihydropyridines have weak vasodilator effects, but can slow down cardiac contraction and conduction.
1) Dihydropyridine CCB
Common drugs: Nifedipine, Felodipine, Amlodipine, etc.
Mechanism: It mainly acts on small arteries and has a strong vasodilator effect; There are few negative effects of force or conduction.
Applicable to: Elderly hypertension, isolated systolic hypertension, with stable angina, coronary or cervical Patients with atherosclerosis and peripheral vascular disease.
Common adverse reactions: Reflex sympathetic activation leading to rapid heartbeat, facial flushing, ankle edema, gingival hyperplasia Wait.
Use with caution in patients: Dihydropyridine CCBs have no absolute contraindications,but Use with caution in patients with tachycardia and heart failure.
Other benefits: In the past large sample antihypertensive clinical trials completed in my country, dihydropyridine CCB-like is the research drug, and it has been confirmed that dihydropyridine-like CCB-based antihypertensive therapy can significantly reduce the risk of stroke in hypertensive patients.
2) Non-dihydropyridine CCB
common drugs: verapamil, Diltiazem.
Mechanism: Acts on blood vessels – dilates blood pressure, but slightly weaker than dihydropyridines; acts on Cardiac – slows cardiac conduction and reduces myocardial contractility, stronger than dihydropyridines.
For: Angina pectoris, carotid atherosclerosis, supraventricular tachyarrhythmias.
Common adverse reactions: Inhibition of cardiac systolic function and conduction function, second to third degree atrioventricular block; Gingival hyperplasia also sometimes occurs.
Contraindicated patients: Because these drugs affect myocardial contraction,contraindicated in patients with heart failure Use .
Notes: A detailed medical history should be taken before the use of non-dihydropyridine CCBs, and < span>ECGcheck, and review within 2 to 6 weeks of medication.
The factors that determine the therapeutic properties of a drug include: chemical structure and tissue selectivity; Duration of action; rate of adverse effects of hypotension; predictability of adverse effects; incidence and severity of adverse reactions. The therapeutic properties of various CCB drugs are shown in Table 1.
Table 1. Therapeutic properties of various types of CCB drugs
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2. How to correct Choose dihydropyridine CCB drugs
Nifedipine Ordinary Tablets: Oral absorption is rapid and complete, with short duration of action, requiring multiple administrations per day; The function of the sinoatrial node and atrioventricular node has little effect. A drop in blood pressure can cause reflex tachycardia.However, its “sudden release” phenomenon can easily cause facial fever, flushing, headache, dizziness, tachycardia, Ankle edema, frequent urination and fatigue. FDA Warning: Short-acting nifedipine increases the risk of myocardial infarction. In addition, short-acting nifedipine is not recommended for hypertensive emergencies.
Nifedipine Extended Release Tablets: After oral administration, the drug is released at a first-order rate. Compared with ordinary tablets, it has the characteristics of maintaining stable blood drug concentration, long-term effect, high efficiency and low adverse reactions. However, taking this class of drugs twice a daymaintains effective blood levels better than taking it once a day.
NifedipineControlled-release Tablets: After oral administration, the drug is released at a zero-order rate, and the drug is released at a constant speed to obtain a more stable and small fluctuation range of blood drug concentration, which can avoid the “burst release” phenomenon of ordinary preparations. , reduce the irritation to the gastrointestinal tract, reduce the frequency of medication and systemic side effects, and once a day can also improve patient compliance.
Felodipine Sustained-Release Tablets: Sustained-release, oral absorption is complete but the first Over-effect is obvious. It has a good antihypertensive effect and good vascular selectivity.It can dilate the coronary arteries, cerebral blood vessels and peripheral blood vessels, and can reduce peripheral blood vessels under conventional doses resistance and systemic blood pressure, but it does not affect the systolic and conduction state of the heart, and can selectively dilate small arteries to achieve hypotensive effect, which can affect the blood vessels The ratio of the intensity of action to the myocardium is 100:1. Also has mild natriuretic and diuretic effects, which may slightly increase or have no effect on renal blood flow, no effect on glomerular filtration rate, and almost no effect on electrolytes , but also inhibit the development of left ventricular hypertrophy in hypertensive patients.
Amlodipine: It is well absorbed orally and is not affected by food. After 6 to 12 hours, the plasma concentration reaches the peak, and the half-life reaches 45 hours. It can prevent the extracellular calcium ions of the heart and vascular smooth muscle from entering the cells through the cell membrane calcium channel, leading to the relaxation of the myocardium and vascular smooth muscle, and can also inhibit the release of norepinephrine from sympathetic nerve endings, increasing the concentration of catecholamines in the plasma. It mainly acts on peripheral blood vessels, but also on coronary arteries and renal arteries, affecting human sinoatrial node and The atrioventricular node was not affected. Provides stable blood levels for 24 hours. After drug withdrawal, there is no “rebound phenomenon” in blood pressure, and has a protective effect on target organs such as the heart, brain, and kidney. It is more suitable for patients with cardiac conduction disorder or renal insufficiency, especially for elderly patients with coronary heart disease. Levoamlodipine has higher bioavailability and fewer adverse reactions than amlodipine.
3. How to Correct combination of dihydropyridine CCB drugs Drugs have become the basic method of antihypertensive treatment. The optimized combined treatment regimens of CCB and other drugs that are mainly recommended in clinical practice in my country are as follows:
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Two-drug combination
Dihydropyridine CCB + ACEI or ARB:
increase the antihypertensive effect at the same time , ACEI or ARB can reduce or counteract CCB-induced ankle edema (this may be related to ACEI or ARB blocking RAAS, which dilates both arteries and veins, thereby reducing dihydrogen pyridine CCBs); partially blocked the adverse effects of increased reflex sympathetic tone and increased heart rate caused by CCBs.
Dihydropyridine CCB + thiazide diuretics:
Increase the antihypertensive effect, while reduce the risk of stroke in hypertensive patients.
Dihydropyridine CCB + β-blockers:
< span>At the same time of increasing blood pressure, CCB has the effect of dilating blood vessels and slightly increasing heart rate, just offset the effect of β-blockers on vasoconstriction and slowing down heart rate. Combination can reduce adverse reactions.
Three-drug combination
Dihydropyridine CCB + ACEI (or ARB) + thiazide diuretic agent.
Four-drug combination
Mainly suitable for refractoryFor patients with hypertensive hypertension, a fourth drug such as beta-blockers, aldosterone receptor antagonists, triamterene, clonidine or alpha-blockers can be added on the basis of the above three-drug combination.
4. How about special groups Select use dihydropyridine CCB drugs
Pregnancy with hypertension:
Nifedipine: Oral, ordinary tablet 5-20 mg q8h ;
Nicardipine: Oral: initial dose of 20-40 mg, 3 times a day; intravenous infusion: starting at 1 mg per hour The initial dose should be adjusted every 10 minutes according to changes in blood pressure; for hypertensive emergencies, after diluting with normal saline or 5% glucose injection, nicardipine hydrochloride, 0.01% to 0.02% (the content in 1 mL is 0.1%) ~0.2 mg) solution for intravenous infusion. Administer at an infusion rate of 0.5 to 6 μg/kg per minute.
Hypertension in children and adolescents:
< p>Amlodipine: Oral, effective for children 6 to 17 years old, the recommended dose is 2.5 to 5.0 mg, once a day.
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