Pharmacology for Dentistry

180 Section 4/ Drugs Acting on Cardiovascular & Urinary System

After oral administration it is rapidly
and extensively absorbed. Metabolism is
primarily hepatic.

Adverse effects include postural
hypotension, dizziness, headache, fatigue,
Gl disturbances and dry eyes.

LABETALOL

It is a mixed antagonist (ααααα 1 and non-
selective βββββ-receptor antagonist). It has
intrinsic sympathomimetic activity which is
largely confined to β 2 adrenergic receptors.
It is more potent in blocking β than a
receptors. It is a potent hypotensive agent
especially useful in pheochro-mocytoma.

After oral administration it is well
absorbed and extensively metabolised in
liver.

ACE INHIBITORS

These drugs act primarily by suppressing
renin-angiotensin-aldosterone system.

The main action of all ACE inhibitors is
to inhibit conversion of angiotensin I
(inactive) to angiotensin II (active). They
inhibit the angiotensin converting enzyme
(ACE). Hence, angiotensin II production is
inhibited. Decrease in angiotensin II results
in dilatation of peripheral vessels leading to
a reduction in systemic vascular resistance
and a decreased aldosterone secretion. They
can be administered safely in patients of
hypertension with diabetes mellitus or
bronchial asthma. ACE inhibitors are
efficacious drugs, are well tolerated and are
useful antihypertensive drugs. ACE
inhibitors are also used in coronary artery

diseases. They reduce cardiovascular

morbidity and mortality by improving

coronary perfusion, reducing ventricular

hypertrophy and remodeling and preventing

progression of coronary atherosclerosis.

However, the cellular mechanisms

underlying the beneficial effects of ACE

inhibitor are not fully understood.

They are now first line drug in all grades

of hypertension. They can be safely

combined with diuretics and β blockers.

CAPTOPRIL

After oral administration it is absorbed

rapidly, the drug is partly metabolised and

partly excreted unchanged in urine. The

excretion is impaired in renal dysfunction.

Adverse effects include dry cough, skin

rash, loss of taste, hyperkalemia, vertigo,

headache, nausea, vomiting, hypotension,

fatigue, neutropenia (rare), proteinuria and

anaemia.

It is indicated in all grades of

hypertension, CHF and scleroderma crisis.

ENALAPRIL

Enalapril maleate is an orally active

angiotensin converting enzyme (ACE)

inhibitor, it lowers peripheral vascular

resistance without causing an increase in

heart rate. The maleate salt (enalapril)

allows better absorption after oral

administration. It is an ideal drug for

hypertensive patients who are intolerant to

beta-blocker therapy. It also shows promise

in the treatment of congestive heart failure.

Following oral administration, enalapril is

rapidly absorbed and hydrolysed to