Antihypertensives

Pharmacological treatment of high blood pressure (hypertension) is one of the cornerstones of internal medicine and a medicine against high pressure (antihypertensive drug) is present in chronic medication of the majority of elderly people. We distinguish two major forms of hypertension:

Primary hypertension

Primary hypertension is present in about 95% of people with high blood pressure. It is caused by a combination of more factors including obesity, unhealthy diet, high sodium intake, lack of physical exercise, age, genetics, etc. Pharmacological therapy is focused mainly on this group of patients.

Secondary hypertension

This diagnosis includes remaining approximately 5% of cases with high blood pressure. Secondary hypertension means that the high blood pressure is directly caused by another disease. These include narrowing of renal artery, certain kidney diseases (e.g. glomerulonephritis), certain hormonal disorders (Cushing's syndrome, Conn's syndrome) and many others. Antihypertensives are also important in the therapy of the secondary hypertension, but they are less effective. Curative therapy of these conditions must include removal of the underlying disease, if possible.

Antihypertensive agents

ACE-Inhibitors

These are one of the best antihypertensives and that is why I have decided to give them their own article. ACE-Inhibitors have a complex effect. In addition to decrease of the blood pressure, they also protect heart muscle and kidney tissue. ACE-Inhibitors include the following active substances – ramipril, captopril, enalapril, perindopril and lisinopril. Their main side effect is an unpleasant dry cough. It occurs only sometimes, but it is very annoying and usually leads to discontinuation of ACE-Inhibitors.

Sartans

These drugs are largely similar to ACE-Inhibitors. They are a little bit less effective and we usually serve them to people, who do not tolerate the ACE-Inhibitors. The most commonly used active substances are - losartan, valsartan and irbesartan. More information can be found in text dedicated to sartans.

Renin inhibitors

These modern drugs block the compound renin, which is produced by kidney tissue. This substance is at the beginning of the so-called RAS system, whose later stages are blocked by ACE-Inhibitors and sartans. Example of renin inhibitor is active substance aliskiren.

Calcium channel blockers

These are commonly prescribed antihypertensives; they are great in combination with ACE-Inhibitors. Some older calcium channel blockers could be dangerous, when combined with medicines causing bradycardia like the beta-blockers. Probably the most common side effect of calcium channel blockers is swelling of the lower extremities. Active compounds of calcium channel blockers are for example verapamil, diltiazem, amlodipine, nitrendipine, felodipine, isradipine and lacipidine.

Diuretics

These substances belong among the oldest hypertensives. They reduce the blood pressure by increasing water loss into the urine. Diuretics are great in patients with high blood pressure and heart failure. The main disadvantages are too excessive loss of fluid and ions, causing dehydration and disruption of the internal environment. Most commonly used substances with diuretic effect are hydrochlorothiazide, furosemide, indapamide, spironolactone and amiloride.

Nitrates

Nitrates are drugs that release nitric oxide (NO) in the arteries, causing relaxation of smooth muscles in the arterial walls, thereby reducing the blood pressure. However, the main importance of nitrates is their effect against chest pain in angina pectoris. We usually use nitrates not in the chronic therapy of hypertension, but rather in management of acute increase of high blood pressure.

Beta-blockers

This is a commonly used group of drugs. They not only decrease the blood pressure, but they also slow the heart rate, reduce the load of the heart and prevent cardiac arrhythmias. They are typically used in small doses in therapy of heart failure, in cardiac rhythm disorders, after myocardial infarction and many other diseases. There are many active substances of beta-blockers such as acebutolol, betaxolol, bisoprolol, carvedilol, celiprolol, metoprolol, nebivolol and others. A major disadvantage of these drugs is the risk of bradycardia and hypotension. Some of them should not be used in people with COPD and asthma, because they cause narrowing of the bronchial tubes. 

Drugs blocking alpha receptors (alpha-adrenergic blockers)

There are three main groups of antihypertensives affecting the alpha-receptors.

 

a) Drugs acting on central alpha receptors

These drugs are usually used in combination with other antihypertensive agents. They are usually not the drugs of first choice. An example of these drugs is substance known as moxonidine

 

b) Drugs acting on peripheral alpha receptors

Drugs of this group have also a positive effect on enlarged prostatic tissue and therefore, they are handy in older men with hypertension, who also suffer from symptoms of enlarged prostate. This type of drug is for example doxazosin.

 

c) Drugs acting on both central and peripheral alpha receptors

Te drugs are usually also used in combinations with other antihypertensives. The most commonly prescribed drugs of this group contain a substance known as urapidil.

 

Combined preparations

Combined preparations are drugs that consist if more active substances in one pill. Very popular combinations are ACE-Inhibitor (sartan) + calcium channel blocker and ACE-Inhibitor (sartan) + diuretic.