7-6. DIURETICS IN THE TREATMENT OF HYPERTENSION
The effectiveness of diuretics in the treatment of essential hypertension arises
from the fact that diuretic agents decrease tubular reabsorption of sodium, which
caused a reduction in blood pressure. Some of the common diuretics include
hydrochlorothiazide, spironolactone (Aldactone), furosemide (Lasix), and triamterene
(Dyrenium). These agents will be discussed in detail in Lesson 8 of this subcourse.
7-7. COMBINATION THERAPY IN THE TREATMENT OF HYPERTENSION
When diuretics alone are ineffective in controlling hypertension, it is necessary to
combine the diuretic therapy with one or more additional agents. The physician may
use many combinations of agents in order to control the patient's high blood pressure.
The patient should be encouraged to discuss any questions he might have concerning
the side effects (for example, drowsiness), which might be caused by an agent or
Section II. DRUGS USED IN THE TREATMENT OF HYPERTENSION
For this discussion commonly used antihypertensive agents will be classified
into the following categories.
7-8. DRUGS WHICH ACT ON THE SYMPATHETIC NERVOUS SYSTEM
For a review of the sympathetic nervous system you should refer to
Subcourse MD0805, Pharmacology II.
a. Methyldopa (Aldomet). Methyldopa is one of the drugs of this type. It is
believed to produce its effects by its being metabolized to a substance which is very
similar to norepinephrine--but with considerably less vasoconstricting activity than is
shown by epinephrine. Thus, methyldopa competes with norepinephrine and thereby
depresses the activity of the sympathetic nervous system. This medication is rarely
used but is still one of the drugs of choice for pregnancy-induced hypertension. Side
effects associated with this agent include bradycardia, swelling of the feet and lower
legs (because sodium and water retention), drowsiness, and mental depression.
b. Clonidine (Catapres, Catapres TTS). Clonidine is an agent that is
believed to act by decreasing sympathetic outflow from the brain and consequently
inhibit vasoconstriction. It is used in mild to moderate hypertension. Side effects
associated with this agent include swelling of the feet and lower legs (due to sodium
and water retention) and mental depression. The patient taking this drug should be
cautioned to check with his physician before suddenly discontinuing the medication
because abrupt withdrawal from the drug may cause serious hypertension problems.
Clonidine is also used in the treatment of symptoms associated with alcohol withdrawal.