Antihypertensive  drugs are defined as any substance or procedure used to reduce blood pressure. Antihypertensive drugs are a group of exclusive drugs for hypertension.

The use of these drugs aims to reduce cardiovascular morbidity and mortalityand the only way to do so is by normalizing blood pressure and controlling cardiovascular risk factors. D icha normalization is modified by changing to lead a healthy lifestyle, avoiding the vices. The following figures fall into a normal range:

• In PA office:
• With control at home:
• With ambulatory PA monitoring (MAP):

Physiology of antihypertensive drugs

Angiotensin II is defined as a peptide that arises from the activation of the Renin Angiotensin System. For the sartanes increase plasma levels of bradykinin , which is a vasodilator that contributes antihypertensive effects. It also stimulates the synthesis of aldosterone, which in turn increases the reabsorption of sodium and water.

The actions of angiotensin II happen thanks to two types of receptors :

• The AT1 : are found in vascular smooth muscle, brain, kidney and lung.
• AT2 : are found in the reproductive organs, in fetal tissue and in the brain.

In other words, the strings avoid binding to their main receiver: the AT1. Therefore, they are effective drugs for the control of arterial hypertension, heart failure, hypertrophy of the left ventricle and prevent heart attacks.

Action mechanisms

Angiotensin II receptors are antihypertensives that have gained strength in recent years in the field of control of high Blood Pressure and heart failure. An example of this type of antihypertensive is losartan. From the latter, they have gone on sale: candesartan, eprosartan, irbesartan, among others.

These drugs are responsible for blocking the enzyme angiotensin II, called AT receptor. Once AT receptors are blocked, vasodilation occurs , vasopressin secretion is reduced, there is less production of aldosterone. Therefore, blood pressure decreases.

Dr. Enrique Parafioriti explains that competitive antagonists of angiotensin II receptors (of the AT1 subtype that AT2) as this peptide can be synthesized outside of the RAS, the AT1 blockers exert a more effective control of the action than the ACEIs. For example, in the heart, the most important route of its synthesis is not through the SRA, but by a serine protease.

However, it should be noted that the effectiveness of each medicine depends on three pharmacodynamic and pharmacokinetic characteristics , which are: inhibition, affinity and efficacy. 

Inhibition

This parameter allows us to analyze the blocking or inhibition of the effect that angiotensin II has on blood pressure. Among them are:

• Valsartan 80mg 30%.
• Telmisartan 80mg 40%.
• Losartan 100mg 25-40%.
• Irbesartan 150mg 40%.
• Irbesartan 300mg 60%.
• Olmesartan 20mg 61%.
• Olmesartan 40mg 74%.

Affinity

This is the affinity of some inhibitors:

• Losartan 1000 times
• Telmisartán 3000 times.
• Irbesartan 8500 times.
• Olmesartan 12500 times.
• Valsartan 20000 times.

Effectiveness

Below are some indicators of the time it takes for the medication to have an effective result.

• Valsartan 6 hours.
• Losartán 6-9 hours.
• Irbesartan 11-15 hours.
• Olmesartan 13 hours.
• Telmisartan 24 hours.

Actions

Antihypertensive drugs cause a gradual decrease in blood pressure without altering the heart rate. It is clear that from the first dose there will be a hypotensive effect, however it is important to maintain the treatment for up to 4 weeks. These are some of its effects:

• They cause a regression of left ventricular hypertrophy.
• Decrease atrial and ventricular dilation in patients with acute myocardial infarction (AMI).
• They diminish the vascular resistance in the kidneys, which, in turn, increases renal plasma flow and urinary sodium excretion.

Adverse effects

• Insomnia.
• Dizziness
• Drowsiness.
• Headaches.
• Low blood pressure
• Increase potassium levels.
• Diarrhea or stomach distention
• Respiratory infections: sinusitis, cold, nasal congestion.

Interactions

• When combined with sparing diuretics, hyperkalamia may occur.
• The intake of alcohol can lower blood pressure, cause dizziness and drowsiness.
• If combined with other antihypertensive drugs, they can cause severe hypertension.
• Consuming amphetamines, asthma medications or decongestants, decreases the therapeutic effect of the strains.

recommendations

Meanwhile, although the patient is prescribed a medication, it is necessary to combine it with healthy lifestyle habits. The measures recommended most frequently are the following:

• Avoid sedentary lifestyle.
• Control body weight
• Avoid alcoholic beverages and tobacco.
• Eat a diet rich in potassium and calcium.
• Reduce sodium intake
• Try to avoid stress.

Contraindications

Any drug belonging to the category of the strains should not be ingested during pregnancy , particularly in the second and third trimesters, since they can cause:  hypotension, renal failure, fetal death. On the other hand during lactation it causes the heart not to pump blood adequately, which causes problems  in the metabolic and synthetic function of the liver. 

References

PARAFIORITI Enrique, Pharmacology of arterial hypertension. Argentina: Model Unit of Arterial Hypertension of the Guemes Sanatorium, 2004.

CADIME Andalusian School of Public Health. Antihypertensive antagonists of angiotensin II receptors: update. Spain: 2000.

GOROSTIDI Pérez M, Council Alfaro B, Prieto Díaz MÁ, Marín Iranzo R. Antagonists of angiotensin II receptors. A pharmacotherapeutic review. Hypertension. 2002

Wikipedia, Hyperkalamia. https://es.wikipedia.org/wiki/Hiperpotasemia

Wikipedia, hypotension. https://es.wikipedia.org/wiki/Hipotensi%C3%B3n