|
|
Drugs that affect the Circulatory/Cardiovascular System |
|
|
|
Drugs that affect the Circulatory/Cardiovascular System |
|
| Heart disease
is one of the death-causing diseases that affect human population
globally. Two common
conditions associated with heart diseases are arteriosclerosis and
hypertension. Arteriosclerosis is the accumulation of plaque (cholesterol
and fatty acid deposits) on the inner walls of arteries, which reduces
blood flow to the heart. Substantial
blockage of coronary artery by plaque can result in a heart attack.
Hypertension (high blood pressure) happens when the blood
pressure exceeds 140/90, usually causes a narrowing of blood vessels,
which in turn requires the heart to work harder to pump blood. |
|
Cardiovascular
system drugs improve the rate of blood flow to the heart by acting at many sites
in the body through various mechanisms. Three
important drugs are diuretics, beta-blocking agents and calcium channel blocking
agents.
Diuretic drugs
work by reducing or eliminating extracellular fluid from the body by increasing
the amount of urine released. Dyazide,
which contains the components hydrochlorothiazide and triamterene (present in a
1:2 mass ratio), is the most widely used diuretic antihypertensive agent.
Beta-receptor
sites are found in heart muscles, which are stimulated, by the adrenal gland
secretions epinephrine and norepinephrine to cause an increased in cardiac
activity. Beta-blocking agents work
by blocking the action of epinephrine and norepinephrine at beta-receptor sites,
which helps to decrease heart rate, allowing an overworked heart to relax and
thereby strengthen itself. Beta-blocking
agents can help to decrease blood pressure as it can relax the blood vessels by
binding itself to the beta-receptor sites of the blood vessels. Two examples of heart drugs are Inderal and Tenormin.
Calcium ions trigger heart muscle to contract through membrane channels surrounding each cell. After contraction, these ions move out of the cell, causing it to relax. Blocking the flow of calcium ions into a cell causes the heart muscle to relax, which results in the expansion (dilation) of the coronary arteries as well as an increase in the blood supply to the heart. Calcium blockers work by decreasing the force of heart muscle contraction and thus decrease the oxygen requirements of the heart. The two most used drugs are Procardia and Cardizem.
