Study Set Content:
Most of the drugs in this class are well absorbed
after
oral administration;
Most of the drugs in this class are well absorbed
after oral administration; peak concentrations
occur () after ingestion
1-3 hours
(blank) preparations of propranolol
and metoprolol are available.
Sustained-release
Propranolol undergoes extensive hepatic (first-
pass) metabolism; its bioavailability is relatively
low
The proportion of drug reaching the systemic
circulation increases as the dose is
increased
Propranolol oral administration of the drug leads
to much () drug concentrations than are
achieved after intravenous injection of the same
dose.
lower
Because the first-pass effect varies among
individuals, there is great individual variability in
the plasma concentrations achieved after
oral
propranolol
For the same reason, bioavailability is limited to
varying degrees for most B antagonists with the
exception of
betaxolol, penbutolol, pindolol, and
sotalol.
are rapidly distributed and have
large volumes of distribution.
The B antagonists
are quite lipophilic
and readily cross the blood-brain barrier
Propranolol and penbutolol
Most B antagonists have half-lives in the range of
3-10 hours.
Most B antagonists have half-lives in the range of
3-10 hours. A major exception is (), which is
rapidly hydrolyzed and has a half-life of
approximately 10 minutes.
esmolol
are extensively
metabolized in the liver, with little unchanged
drug appearing in the urine.
Propranolol and metoprolol
are less
completely metabolized
Atenolol, cellprolol, and pindolol
is excreted unchanged in the urine and
has the longest half-e of any available antagonist
(up to 24 hours)
Nadolol
Beta-blocking drugs given chronically lower blood
pressure in patients with
hypertension
The mechanisms involved are not fully
understood but probably include suppression of
() and effects in the central nervous
system.
renin release
These drugs do not usually cause hypotension in
healthy individuals with normal blood pressure
• Beta-receptor antagonists have prominent effects
on the heart and are very valuable in the treatment
of angina and chronic heart failure and following
myocardial infarction.
Blockade of the B2 receptors in bronchial smooth
muscle may lead to an () in airway
resistance, particularly in patients with asthma.
increase
may have some
advantage over nonselective B antagonists when
blockade of B 1 receptors in the heart is desired
and B 2-receptor blockade is undesirable
Metoprolol and atenolol
