Study Set Content:
These drugs should generally be avoided in
patients with asthma. On the other hand, many
patients with () may tolerate these drugs quite
well and the benefits, for example in patients with
concomitant ischemic heart disease, may
outweigh the risk
chronic obstructive pulmonary
disease (COPD)
reduce intraocular pressure,
especially in glaucoma.
Beta-blocking agents
The mechanism usually reported is decreased
aqueous humor production
+Beta-receptor antagonists such as propranolol
() sympathetic nervous system stimulation of
lipolysis
inhibit
is the primary hormone used to combat
hypoglycemia; it is unclear to what extent ß
antagonists impair recovery from hypoglycemia,
but they should be used with caution in ()
dependent diabetic patients
Glucagon, insulin
may be less prone
to inhibit recovery from hypoglycemia
Beta 1-receptor-selective drugs
are much safer in those
type 2 diabetic patients who do not have
hypoglycemic episodes
Beta receptor antagonists
Partial B-agonist activity was significant in the
first B-blocking drug synthesized,
dichloroisoproterenol.
() also known as
"membrane-stabilizing" action, is a prominent
effect of several B blockers.
Local anesthetic action
This action is the result of typical local anesthetic
blockade of () and can be
demonstrated experimentally in isolated neurons,
heart muscle, and skeletal muscle membrane.
sodium channels
is a nonselective 3-receptor antagonist
that lacks local anesthetic action but has marked
class III antiarrhythmic effects, reflecting
potassium channel blockade.
Sotalol
a is the prototypical ß-blocking drug
• It has low and dose-dependent bioavailability.
PROPANOLOL
A long-acting form of propranolol is available;
prolonged absorption of the drug may occur over
a
24-hour period.
The drug has negligible effects at a and muscarinic
receptors; however, it may block some () in the brain, though the clinical
significance is unclear.
serotonin
receptors
PROPANOLOL has no detectable () action at 3 receptors
3 receptors
These agents may be safer in patients who
experience bronchoconstriction in response to
propranolol
METOPROLOL, ATENOLOL, AND SEVERAL
OTHER DRUGS ARE MEMBERS OF THE B1-
SELECTIVE GROUP.
They should be used with great caution, if at all, in
patients with a history of asthma. Selected
patients with COPD the benefits may exceed the
risks, eg, in patients with
myocardial infarction.
may be preferable in
patients with diabetes or peripheral vascular
disease, since 32 receptors are probably important
in liver (recovery from hypoglycemia) and blood
vessels (vasodilation).
Beta 1 selective antagonists
Is the most highly selective B1-adrenergic receptor
blocker
NEBIVOLOL
Though some of its metabolites do not have this
level of specificity. Nebivolol has the additional
quality of eliciting
vasodilation.
