LESSON 7
ANTIHYPERTENSIVE AGENTS
Section I. INTRODUCTION TO HYPERTENSION
7-1. INTRODUCTION
a. It is estimated that 23 million people in the United States suffer from
hypertension. Of this number, it is thought that 11.5 million people have been
diagnosed as having the condition and that 5.75 million of those people are being
treated for it. Unfortunately, it is estimated that only 2.875 million of those persons
treated for hypertension are being treated properly. Therefore, it is obvious that
hypertension is a major medical problem which should be a concern of all medical
personnel.
b. Hypertension (high blood pressure) is prevalent in both men and women. It
frequently contributes to the death of many persons. The cause of most cases of
hypertension is unknown. This type of hypertension is referred to as primary or
essential hypertension. Hypertension that has a known cause (kidney disease,
hyperthroidism) is called secondary hypertension. Blood pressure is the force that the
blood exerts on the vessel wall while the heart is contracting and at rest. The force
against the vessel wall during contraction or systole is the systolic pressure and the
force during rest or diastole is the diastolic pressure. The blood pressure is expressed
in terms of millimeters of mercury (Hg). Normal blood pressure is less than 135 mm Hg
(systolic) and less than 85 mm Hg (diastolic) = 135/85 mm Hg.
7-2. TREATMENT OF HYPERTENSION
There is no cure for hypertension. Most patients who have a bacterial infection
are accustomed to taking a 10-day treatment regimen of an antibiotic in order to rid
themselves of the infection. The same is not true with hypertension. Once a person
begins taking an antihypertensive agent, it is likely that he will continue taking some
type of antihypertensive agent for the rest of his life.
7-3. DEFINITION OF ESSENTIAL (PRIMARY) HYPERTENSION
Essential (primary) hypertension can be defined as a disorder of unknown origin
characterized mainly by an elevated systolic or diastolic blood pressure associated with
generalized arteriolar vasoconstriction (see Lesson 2). Essential hypertension may be
divided into three classes according to the severity of the condition. Labile hypertension
is a condition of elevated blood pressure with intervening periods of normal blood
pressure.
MD0806
7-2