Medicine Answer-1

Answer is (B) Epinephrine is the drug of choice in the treatment
of anaphylaxis because it provides a pressor
response through alpha-1-adrenoceptor actions,
cardiac stimulation through beta-1-adrenoceptor
actions, and bronchodilation and prevention of
mast cell release of histamine and leukotrienes
through actions on beta-2 adrenoceptors. The
actions of dopamine (choice A) on the cardiovascular
system are complex; dopamine exerts effects
on renal, mesenteric, and myocardial vascular D1
receptors (vasodilation), cardiac beta-1-receptors
(positive inotropic effect), and vascular alpha-1-
receptors (vasoconstriction), depending on the
dopamine concentration. Dopamine may also
cause release of norepinephrine from sympathetic
nerve terminals, but it does not inhibit mast cell
release of mediators of shock nor does it cause
bronchodilation. Dopamine is useful in hypovolemic
and cardiogenic shock in maintaining
renal perfusion. Isoproterenol (choice C)
inhibits mast cell release of mediators and provides
cardiac stimulation and bronchodilation,
but does not provide needed pressor activity.
Norepinephrine (choice D) provides pressor
activity to treat hypotension, but does not
inhibit mast cell release of mediators of shock
and does not dilate the bronchi. Phenylephrine
(choice E), like norepinephrine, provides pressor
activity, but not cardiac stimulation or inhibition
of mast cell function.

Posted in: Medicine Questions