Hypertension is an elevation in blood pressure (BP) of at least 140/90 on several consistent readings. The higher the blood pressure, the more the likelihood that there will be medications recommended in addition to lifestyle modifications. To fully understand how these medications work, it is helpful to have an understanding of basic anatomy and chemistry. Some drugs also work differently in people of different ethnic backgrounds and health conditions, as well as pregnant women, so it is important to review these things with your doctor.
Diuretics and Beta Blockers
The most common types of prescribed medications are thiazide diuretics and beta blockers. They are often prescribed together for maximum effect. The diuretics work with the kidneys to help decrease the amount of water and sodium in the body, therefore reducing the volume of fluid in the blood vessels, which in turn should help decrease the pressure. The beta blockers work by slowing the heart contractions down--not only in rate, but strength of contraction as well. This has the overall effect of lowering blood pressure, since the speed and rate with which blood is flowing through the blood vessels is slower. These medications are usually the first and least expensive method of reducing BP.
Calcium Channel Blockers
Another classification is calcium channel blockers, which have a similar action to that of beta blockers in that they slow the contraction power and rate of the heart. they are more potent drugs, and come in short-acting and long-lasting doses. The online Merk manual recommends Ca +2 channel blockers over beta blockers for those who have associated heart pain (angina pectoris).
ACE Inhibitors and Angiotensin II Receptor Blockers
Angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers work by essentially blocking the ability to make the signal that tells the blood vessels to narrow, or blocking the chemical signal itself. When the blood vessels narrow, the pressure goes up. So by not allowing them to narrow, they keep the blood pressure low. These drugs are also useful for those who have kidney and coronary artery issues.
Renin Inhibitors
Renin inhibitors are drugs that work at the level of the kidneys to stop the production of rennin. Renin is a chemical that starts the cascade of processes to increase blood pressure in the body.
Other Classifications
There are also less commonly used drugs like androgenic modifiers and vasodilators. Androgenic modifiers work at the level of the brain to try to combat the response of the sympathetic nervous system ("fight or flight") to try to keep the blood pressure low, while the vasodilators work directly on the muscles within the blood vessel walls and prevent them from constricting. Both of these drugs are not commonly prescribed anymore due to their potentially severe side effects when combined with other medications, as hypertension is not a disease by itself and is often accompanied by other heart or metabolic diseases, so the medications have to also be able to work with the other prescription drugs.
