AlphaBlockers

Question 1

Where are alpha receptors located in the body?

Answer 1

skin, splanchnic vessels and skeletal muscles, where they contract vessels when activated

Question 2

What is doxasoin? What receptor is it specific for?

Answer 2

Alpha blocker with much greater specificity for A1

Question 3

What is terazosin? What receptor is it specific for?

Answer 3

alpha blocker with much greater specificity for A1

Question 4

What is prazosin? What receptor is it specific for?

Answer 4

alpha blocker with much greater specificity for A1

Question 5

What is pheoxybenzamine? What receptor is it specific for?

Answer 5

alpha blocker with just slightly greater specificity for A1 than A2 (almost equal). Is non-competitive because it binds covalently and thus has very long action. Can produce tachycardia, raynauds, drowsiness.

Question 6

What is phentolamine? What receptor is it specific for?

Answer 6

alpha blocker with no specificity. Short acting competitive binding. DOSE DEPENDENT EFFECT. small doses lead to selective block of A2, thus increase NE effects and increase in BP. Large doses lead to selective A1 block and reduction in BP. Can cause reflex tachycardia.

Question 7

What is yohimbine? What receptor is it specific for?

Answer 7

alpha blocker with greater specificity for A2

Question 8

What is the chemical pathway for alpha1 adrenergic receptor activation?

Answer 8

NE or E binds to A1 receptor, which upregulates membrane phosphoinositides,which form DAG and IP3, which increases intracellular Ca

Question 9

What receptors does norepinephrine target?

Answer 9

A1, A2, B1

Question 10

What receptors does epinephrine target?

Answer 10

A1, A2, B1, B2

Question 11

What receptors does isoproterenol target?

Answer 11

B1, B2

Question 12

What would happen to blood pressure if an alpha antagonist were given with epinephrine?

Answer 12

The BP would drop because the sympathetic actions of epinephrine would be blocked, but the parasympathetic action on B1 and B2 receptors would not, causing vasodilation and a decrease in HR, reducing BP.

Question 13

What is alfuzosin?

Answer 13

an A1 blocker with specificity for A1-a, which makes it useful in treating BPH

Question 14

What are some of the main adverse effects of alpha blockers?

Answer 14

1st dose orthostatic hypotension.

Sinus-tachycardia, syncope, vertigo if a high does is given because of blockage of A2 receptors.

Question 15

Which of these has the longest half life: doxasozin, terazosin, prazosin?

Answer 15

Doxazosin has a half life of 22 hours, which is the longest, allowing it to be given once daily. Terazosin is 12 hours, but can still be given daily. Prazosin is 4 hours and must be given 3 times daily, making it less practical