Blood Pressure Medicine Types

High blood pressure, or hypertension, is a very common condition. Most of the time the cause is unknown, and no symptoms are experienced. However, after many years, high blood pressure raises the risks of other problems such as heart attacks and strokes. It is first treated with lifestyle changes such as a proper diet and exercise. If these interventions do not work, a health care provider may recommend drug therapy.

Thiazide Diuretics

Diuretics are drugs that cause the kidneys to remove more fluid from the blood to produce a greater volume of urine. These drugs reduce the overall blood volume, which in turn lowers the blood pressure. Drugs in this class include hydrochlorothiazide and chlorthalidone. They inhibit channels in the kidneys that take up electrically charged minerals called electrolytes, causing the electrolytes to be shunted through the tubes of the kidneys, called nephrons, into the bladder, and water follows. Side effects include increased levels of blood sugar and fats, and decreased potassium, sodium and magnesium.

ACE Inhibitors and ARBs

Angiotensin and aldosterone are both hormones in the blood that increase blood pressure. ACE inhibitors, or angiotensin-converting-enzyme inhibitors, stop an enzyme from activating the angiotensin molecule, a protein, to a more active form that constricts blood vessels and raises the blood pressure. ARBs, or angiotensin receptor blockers allow the conversion to the more active form, but do not allow it to bind to its receptors. Some of the more common side effects may include cough, elevated potassium and headaches.

Beta Blockers

Adrenaline, also known as epinephrine, as well as norepinephrine, are "fight or flight" hormones with many effects on the body including increasing the blood pressure by constricting the blood vessels and making the heart contract more forcefully and at a faster rate. These hormones bind to alpha and beta receptors on cells, and beta blockers prevent them from binding. Side effects include acute heart failure in people with heart conditions, constriction of the airways, low blood sugar, increased blood potassium, weight gain, depression, fatigue and sexual dysfunction.

Calcium Channel Blockers

Calcium is present inside cells and out in the blood and fluids surrounding cells. Muscle cells in the heart and arteries use calcium. Calcium inside the cell causes the muscles to contract. In the heart this leads to more forceful contractions and in the blood vessels, this decreases the diameter of the vessels and therefore increases the blood pressure. By blocking calcium, the heart does not beat as forcefully and the blood vessels dilate. This causes the blood pressure to decreased. Side effects may include fatigue, swelling, heartburn and flushed skin.

Vasodilators

Vasodilators are drugs that dilate the blood vessels. Commonly used vasodilators include hydralazine and nitroprusside. Nitroprusside is likely to be used in emergencies for its quick action, and hydralazine for persons who do not respond to firstline antihypertensive drugs. Hydralazine tends to dilate the arteries, and nitroprusside dilates the arteries and veins.

Centrally Acting Drugs

Centrally acting drugs are those drugs that have an effect on the central nervous system. Clonidine is a drug that acts on the brain to decrease the output of the sympathetic nervous system. This is the part of the nervous system that activates the fight or flight system, so suppressing it helps to decrease the blood pressure. Methyldopa acts centrally as well, and along with hydralazine is a first-line drug to treat high blood pressure during pregnancy.