Deciphering the secrets of beta-blocker application: From diuretic dosage reduction principles to professional guidance on preventing "withdrawal syndrome"

What principles should be followed when using diuretics to lower blood pressure?

① Start with a low dose and gradually increase it according to the patient's condition. This is especially important for elderly patients using potent diuretics to avoid hypotension and electrolyte imbalance. Thiazide diuretics should be used at low doses to achieve the best antihypertensive effect. For example, elderly patients and those with heart failure can start with 6.25 mg, while general patients can start with 12.5 mg, increasing slowly if necessary, generally not exceeding 25 mg per day.

② Medium- or long-acting diuretics, such as hydrochlorothiazide or indapamide, are preferred. If a low dose is insufficient to lower blood pressure, it should be used in combination with other antihypertensive drugs, such as angiotensin-converting enzyme inhibitors, angiotensin II receptor antagonists, or calcium channel blockers. For patients who do not respond to diuretics or have chronic renal failure, potent diuretics, such as furosemide (Lasix), should be used.

③ Sodium intake does not need to be restricted when using diuretics, but a high-salt diet should be avoided, and potassium intake should be appropriately increased.

④ Potassium-sparing diuretics [such as spironolactone (Aldactone)] are weak diuretics with poor efficacy when used alone. They are often used in combination with other diuretics (such as hydrochlorothiazide) to prevent potassium loss from hydrochlorothiazide. Therefore, potassium supplementation may be reduced or eliminated when using this type of drug.

⑤ Potassium supplementation is necessary when using a potent diuretic alone, but not when used in combination with angiotensin-converting enzyme inhibitors.

⑥ Diuretics are not suitable for patients with a history of gout; high-dose diuretics are not suitable for patients with type 1 diabetes, type 2 diabetes, or dyslipidemia.

Why are thiazide diuretics often chosen for lowering blood pressure? Thiazide diuretics, primarily hydrochlorothiazide (HCC), not only reduce blood volume through diuresis but also dilate blood vessels and decrease peripheral resistance, further lowering blood pressure. Thiazide diuretics have a mild and definite antihypertensive effect, lowering systolic and diastolic blood pressure in both standing and lying positions, and can also enhance the efficacy of other antihypertensive drugs. Therefore, thiazide diuretics are often chosen for antihypertensive treatment.

What are the adverse reactions of thiazide diuretics? Thiazide diuretics have relatively few adverse reactions, but long-term use can cause electrolyte imbalances, resulting in weakness, fatigue, dizziness, and mild gastrointestinal symptoms (such as loss of appetite, nausea, vomiting, stomach cramps, stomach discomfort, diarrhea, etc.). The dosage should be reduced to adjust the electrolyte imbalance. However, serious adverse reactions can sometimes occur, including the following:

① Hyponatremia, hypochloremia, and hypokalemic alkalosis: Hypokalemia is the most common. Prevention can be achieved through intermittent therapy, combination with potassium-sparing diuretics, or timely potassium supplementation.

② Hyperglycemia: Long-term or high-dose use can lead to decreased glucose tolerance and elevated blood sugar. This will recover upon discontinuation of the drug. While thiazide diuretics may increase blood sugar levels after use in diabetic patients, the increase is not severe and therefore not a contraindication for their use.

③ Hyperuricemia: Thiazide diuretics can prevent uric acid excretion through the renal tubules, thus increasing blood uric acid levels and worsening gout symptoms.

④ Azotemia: Thiazide diuretics can reduce glomerular filtration rate and blood volume, exacerbating azotemia. Therefore, their use in patients with severely impaired renal function may induce renal failure.
⑤ Increased blood ammonia: These drugs have a weak inhibitory effect on carbonic anhydrase, and long-term use can lead to elevated blood ammonia levels. In patients with severely impaired liver function, there is a risk of inducing liver failure.
⑥ Dyslipidemia: These drugs can increase cholesterol, triglycerides, and low-density lipoprotein (LDL), while decreasing high-density lipoprotein (HDL).

What precautions should be taken when taking thiazide diuretics? The following precautions should be taken when taking this type of medication:

① Gradually reduce the dosage when discontinuing the medication. Sudden discontinuation can cause sodium, chloride, and water retention.

② There is a possibility of cross-allergy with sulfonamides.

③ Because this drug can cross the placenta, it may cause neonatal or fetal jaundice; therefore, pregnant women should not use it.

④ It can be secreted in breast milk; therefore, breastfeeding women should not use it.

⑤ Patients with diabetes, gout, or severe liver or kidney dysfunction should use this medication with caution.

⑥ Patients with oliguria or severe renal impairment should discontinue use if there is no diuretic effect within 24 hours after using the maximum dose.

Why is indapamide commonly used as an antihypertensive drug? Indapamide, also known as sulpiride, sodium thiamethoxam, or indapamide, is a novel long-acting diuretic and antihypertensive drug. It has diuretic and calcium ion antagonistic effects, and has high selectivity for vascular smooth muscle. It can block the influx of calcium ions, reducing peripheral vascular resistance and producing an antihypertensive effect. Its antihypertensive effect is significantly stronger than its diuretic effect. Small doses have a hypotensive effect, while only large doses have a diuretic effect. Its diuretic and hypotensive effects are separate; a therapeutic dose (2.5 mg daily) produces a mild and transient diuretic effect and slowly and steadily lowers blood pressure; increasing the dose does not significantly enhance the hypotensive effect. It has no effect on the central nervous system or autonomic nervous system, and does not change heart rate or cardiac output. Indapamide can control blood pressure within the normal range in approximately two-thirds of hypertensive patients, without affecting cardiac function, renal function, blood sugar, or blood lipids. It does not cause hypokalemia, or side effects such as orthostatic hypotension, tachycardia, or rebound hypertension. It is suitable for grade 1 and 2 hypertension, and for hypertensive patients with renal failure, diabetes, or dyslipidemia, especially elderly patients. This drug can be used alone or in combination with other antihypertensive drugs. The usual dose (2.5 mg daily for adults) is effective. Elderly hypertensive patients can control their blood pressure by taking 2.5 mg every two days. Generally, the effects of medication are visible within 2 weeks; a course of treatment lasts 6-8 weeks. If the effect is unsatisfactory, 5mg can be taken daily in two divided doses for 4-6 weeks.

Which hypertensive patients are suitable for diuretics? Diuretics can be used alone to treat grade 1 and 2 hypertension, and are often used in combination with other antihypertensive drugs to treat moderate to severe hypertension. In antihypertensive treatment, thiazide diuretics are particularly suitable for grade 1 and 2 (mild to moderate) hypertension, elderly patients with hypertension, isolated systolic hypertension, and patients with hypertension complicated by congestive heart failure; loop diuretics (furosemide) are suitable for patients with hypertension complicated by renal insufficiency and congestive heart failure (this type of diuretic is not used as a first-line drug for mild hypertension); potassium-sparing diuretics (spironolactone) are suitable for patients with hypertension complicated by congestive heart failure or after myocardial infarction. In addition, many elderly patients with hypertension suffer from volume-related hypertension. Adding a low-dose diuretic can reduce water and sodium retention, achieving a good antihypertensive effect. Furthermore, low-dose diuretics have almost no adverse effects on glucose metabolism, lipid metabolism, or serum potassium. β-Receptor Blockers 19. What are β-receptor blockers? β-receptor blockers are chemical substances that bind to β-receptors, or in other words, chemical substances that prevent the release of neurotransmitters from the sympathetic nervous system, thereby achieving an antihypertensive effect. Based on the drug's selectivity for receptors, this class of drugs can be divided into non-selective β-receptor blockers (such as propranolol) and selective β1-receptor blockers (such as metoprolol and bisoprolol).

What are some commonly used beta-blockers? How are they used?

(1) First Generation: Propranolol: A short-acting drug with an effective duration of action of 6-8 hours. Tablets, 10mg per tablet, 1-2 tablets per dose, 2-3 times daily. This is a non-selective beta-blocker and is not commonly used for simple antihypertensive therapy.

(2) Second Generation: ① Metoprolol: An intermediate-acting drug with an effective duration of action of 10-12 hours. Tablets, 25mg per tablet, 1/4-1 tablet per dose, 1-2 times daily. ② Bisoprolol: A long-acting drug. Tablets, 5mg per tablet, 1/2-1 tablet per dose, once daily. ③ Atenolol: A long-acting drug. Tablets, 25mg per tablet, 1/2-1 tablet per dose, once daily. (3) Third-generation carvedilol: It has blocking effects on β1, β2, and α receptors. Tablets, 12.5 mg per tablet, one tablet once daily. 21. Which hypertensive patients are suitable for β-blockers? The antihypertensive mechanism of β-blockers is achieved through the combined action of several mechanisms.

Therefore, this class of drugs is suitable for the following types of hypertensive patients:

① Patients with coronary heart disease: such as patients with hypertension and exertional angina, β-blockers can both prevent and treat hypertension and angina. Especially for patients after myocardial infarction, the use of β-blockers can prevent re-infarction and improve patient prognosis.

② Hypertension in young adults: Due to their fast heart rate and large cardiac output, medication can significantly lower blood pressure and improve symptoms. ③ Hypertensive patients with elevated diastolic blood pressure: Clinical studies have shown that this class of drugs reduces diastolic blood pressure more significantly than systolic blood pressure. Therefore, it is suitable for treating patients with isolated diastolic hypertension or for treating hypertension with both high systolic and diastolic blood pressure in combination with other antihypertensive drugs. Because beta-blockers slow the heart rate, heart rate should be closely monitored and maintained above 60 beats/min. Start with a low dose and gradually increase the dosage to achieve a stable blood pressure reduction.
④ Patients with cardiomyopathy and chronic stable heart failure.

⑤ Patients with pregnancy-induced hypertension.