Unit 1 Description of a Pharmacy Grammar

Drugs That Affect Blood Pressure. Vasodilators are drugs which relax the muscles of vessel walls, thus increasing the size of blood vessels. These drugs are used in treating blood vessel diseases, heart conditions, and high blood pressure (hypertension). Blood flows more freely and blood pressure falls as blood vessels open and become dilated. Examples are sympatholytics (reserpine, guanethidine, and alpha-methyldopa) and other agents such as hydralazine.

Nitrites are drugs which are also used as vasodilators. Examples of nitrite drugs are glyceryl trinitrate (nitroglycerin) and amyl nitrite. Nitroglycerin dilates all smooth (involuntary) muscles in the body, but has a greater effect on the muscles of the coronary blood vessels. The relaxation of the muscle fibers around the blood vessels of the heart increases the width of these heart vessels and increases blood flow to the heart muscle. The pain (angina pectoris) caused by a lack of adequate blood flow to the heart is relieved by placing nitroglycerin under the tongue; from there the drug is quickly absorbed into the bloodstream. The other nitrite drugs work in a manner similar to that of nitroglycerin. A third type of drug used to lower blood pressure is called a diuretic, an agent which promotes excretion of fluid and a shrinkage of the volume of blood within the vessels. An example of this type of drug is chlorothiazide (Diuril).