A Complete Guide to Selecting and Using "Dihydropyridine" Drugs: Mechanisms of Action and Prevention of Adverse Reactions of Calcium Channel Blockers

Calcium Channel Blockers (CCBs)

What are calcium channel blockers?

Calcium channel blockers, also known as calcium antagonists, work by inhibiting calcium ion channels in myocardial and vascular smooth muscle cells, reducing the entry of calcium ions into the cells. This deprives these tissues of the calcium ions needed for contraction, thereby causing vasodilation and a decrease in blood pressure. In other words, myocardial and vascular smooth muscle cells contract after stimulation and excitation, and calcium ions act as the "mediator" connecting the excitation and contraction processes.

What are some commonly used calcium channel blockers? Most calcium channel blockers end with "dipine" in their names and are classified into two types according to their chemical structure: dihydropyridine and non-dihydropyridine.

(1) Dihydropyridines

① Short-acting a. Nifedipine immediate-release tablets (Adalat, Nifedipine), 10mg per tablet; or nifedipine immediate-release capsules, 5mg per capsule, 1 tablet or 1 capsule each time, 3 times a day. b. Nifedipine tablets, 10mg per tablet, 1-2 tablets each time, 3 times a day.
C. Nimodipine tablets, 20mg per tablet, 1-2 tablets each time, 3 times a day.

② Intermediate-acting: Nifedipine sustained-release tablets, domestically produced drug, effect lasts 10-12 hours, 20mg per tablet, 1 tablet each time, twice a day.

③ Long-acting:

a. Nifedipine controlled-release tablets (Baixintong), a dosage form with an effect lasting up to 24 hours, manufactured using laser perforation technology, 30mg per tablet, 1 tablet each time, once a day.

b. Finadedipine (Plendil, Plutonil), sustained-release tablets, 2.5mg or 5mg per tablet, initial dose 2.5mg, once a day, maintenance dose 5mg or 10mg. c. Amlodipine (Lovoxi), 2.5mg, 5mg, or 10mg per tablet, initial dose 5mg once daily, gradually increasing to 10mg depending on the condition.

d. Levoamlodipine (Shuhuida), 2.5mg per tablet, one tablet once daily. Gradually increasing to 5mg depending on the condition.
e. Lacidipine (Sileping, Lexiping), 2mg or 4mg per tablet, initial dose 4mg once daily in the morning, increasing to 6mg once daily after 3-4 weeks.

(2) Non-dihydropyridine derivatives
a. Dilthime (Thiodamine, Hexinshuang, Tianerxin), 30mg or 60mg per tablet, 30-60mg three times daily. b. Verapamil (Isoptin, Verapamil, Verapamil), 40mg per tablet; sustained-release tablets, 240mg per tablet, 120-240mg once daily.

What are the effects of calcium channel blockers? Calcium channel blockers are a class of potent antihypertensive drugs that dilate blood vessels and lower blood pressure. Clinical practice has confirmed that these drugs effectively reverse left ventricular hypertrophy, increase perfusion of the brain, heart, and kidneys, and protect the function of the brain, heart, and kidneys, possibly related to significantly reducing peripheral vascular resistance. These drugs also dilate coronary arteries to varying degrees, reduce pulmonary hypertension, dilate bronchial smooth muscle, prevent and treat asthma, have antiarrhythmic effects, inhibit platelet aggregation, protect the vascular endothelium, prevent atherosclerotic plaque formation, reduce cardiac load, reduce myocardial oxygen consumption, and relieve coronary artery spasm. Therefore, they are more suitable for elderly patients with hypertension, coronary heart disease, coronary artery spasm, variant angina, and chronic obstructive pulmonary disease. Long-term use of this product has no adverse effects on blood lipids, blood sugar, uric acid, or electrolytes such as blood potassium and calcium, and will not cause bronchial asthma or peripheral vasoconstriction. This class of drugs has no difference in effect among patients of different races, young people, and the elderly. It will not lower blood pressure further in patients with normal blood pressure. It is more effective in patients with normal renin levels and salt-dependent hypertension. In addition, this class of drugs can also be used in patients with hypertension after heart or kidney transplantation.

Which hypertensive patients are suitable for calcium channel blockers? This class of drugs is suitable for:

① Patients with grade 1, 2, and 3 hypertension;

② Patients with angina or arrhythmia;

③ Patients with peripheral vascular disease, the elderly, and patients with isolated systolic hypertension;

④ Patients with impaired glucose tolerance;

⑤ Patients with concomitant renal impairment;

⑥ Pregnant women.

Which hypertensive patients are not suitable for calcium channel blockers? This class of drugs is not suitable for the following hypertensive patients:

① Patients with heart failure;

② Patients with a history of myocardial infarction;

③ Patients with a pre-existing rapid heart rate;

④ Patients with atrial fibrillation or other arrhythmias.

What adverse reactions should be noted when using calcium channel blockers to lower blood pressure? Calcium channel blockers have the following adverse reactions:

① Tachycardia or palpitations: Commonly seen with dihydropyridine calcium channel blockers, this is a clinical manifestation of reflex tachycardia caused by vasodilation. It is more likely to occur with higher doses. Combining it with beta-blockers can control this adverse reaction.

② Peripheral edema: Found in all types of calcium channel blockers, with dihydropyridines having the highest incidence. It commonly occurs in the ankle, but can also occur in the hand. Patients who sit for long periods are prone to peripheral edema, especially at night. Peripheral edema is related to the vasodilatory effect of this class of drugs. Vasodilation increases capillary pressure, accelerating fluid filtration and increasing interstitial fluid, leading to peripheral edema.

③ Constipation: Commonly seen with non-dihydropyridine drugs, such as verapamil and diltiazem. Higher doses result in more severe constipation, which gradually lessens with prolonged use.

④ Headache and facial flushing: Also related to vasodilation. Generally tolerable. These symptoms gradually disappear with long-term use due to vasomotor mechanisms.

⑤ Gingival hyperplasia: Long-term use of these drugs can lead to gingival hyperplasia, with nifedipine being more common. Gingival hyperplasia usually subsides after discontinuation of the drug.