Pharmacology mcqs (final control) 3rd course

= Bronchospasm

~ They may cause postural hypotension and reflex tachycardia
83- Which of the following drugs is an imidazoline derivative and a potent competitive antagonist at both alfa₁ and alfa₂ receptors?
~ Prazosin
~ Labetalol
~ Phenoxybenzamine

= Phentolamine

84- Characteristics of phentolamine include all of the following EXCEPT:
~ Reduction in peripheral resistance

= Stimulation of responses to serotonin

~ Tachycardia
~ Stimulation of muscarinic, H₁ and H₂ histamine receptors
85- The principal mechanism of phentolamine-induced tachycardia is:

= Antagonism of presynaptic alfa₂ receptors enhances norepinephrine release, which causes cardiac stimulation via unblocked beta receptors

~ Baroreflex mechanism

~ Direct effect on the heart by stimulation of beta₁ receptors
~ Inhibition of transmitter reuptake at noradrenergic synapses
~ Xylometazoline
86- Propranolol has all of the following cardiovascular effects EXCEPT:
~ It decreases cardiac work and oxygen demand

= It reduces blood flow to the brain

~ It inhibits the renin secretion
~ It increases the atrioventricular nodal refractory period
87- Propranolol-induced adverse effects include all of the following EXCEPT:
~ Bronchoconstriction
~ “supersensitivity” of beta-adrenergic receptors (rapid withdrawal)

= Hyperglycemia

~ Sedation, sleep disturbances, depression and sexual dysfunction

88- Which of the following hypnotic agents is able to interact with both BZ₁ and BZ₂ receptor subtypes?

~ Zaleplon
~ Phenobarbital