Alpha Antagonists. Flashcards

1
Q

What are direct acting adrenergic antagonists?

A

Adrenergic receptor blockers or antagonists.

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2
Q

What are the 3 types of alpha receptor antagonists?

A

Non-selective alpha antagonists.

Selective a-1 antagonists.

Selective a-2 antagonists.

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3
Q

What 3 drugs make up the non-selective alpha antagonists?

A

Phenoxybenzamine.

Phentolamine.

Tolazoline.

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4
Q

What 2 drugs make up selective a-1 antagonists?

A

Prazosin.

Terazosin.

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5
Q

What 2 drugs make up selective a-2 antagonists?

A

Yohimbine.

Atipamezole.

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6
Q

What are the 2 types of beta receptor antagonists?

A

Non-selective beta antagonists.

Selective B-1 antagonists.

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7
Q

What are 4 non-selective beta antagonist drugs?

A

Propanolol.

Timolol.

Carvedilol.

Solatol.

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8
Q

Carvedilol will have effects on what receptors?

A

Beta-1 receptors and alpha-1 receptors.

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9
Q

What are 4 drugs that act as selective B-1 antagonists?

A

Metoprolol.

Atenolol.

Esmolol.

Acebutolol.

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10
Q

What is the function of direct acting antagonists?

A

They block receptors

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11
Q

What is the function of indirect acting antagonists?

A

They affect the pathways that lead to the formation of the neurotransmitter.

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12
Q

What are 2 drugs that interfere with the synthesis of catecholamines?

A

Methyl dopa.

Alpha methyl tyrosine.

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13
Q

What is a drug that interferes with the storage of norepinephrine?

A

Reserpine.

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14
Q

What is a drug that prevents the release of norepinephrine?

A

Guanethidine.

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15
Q

What is a drug that decreases sympathetic outflow?

A

Clonidine.

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16
Q

What is the mode of action of phenoxybenzamine?

A

It irreversibly inhibits alpha receptors by preventing the re-uptake of norepinephrine.

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17
Q

What are the pharmacological actions of phenoxybenzamine?

A

It prevents vasoconstriction.

It blocks the A2 receptor in the heart to increase cardiac output.

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18
Q

What is the epinephrine reversal phenomenon?

A

When epinephrine acts through beta receptors as the alpha receptors are blocked.

This leads to vasodilation and this is the opposite of the usual response of epinephrine.

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19
Q

What are the therapeutic uses of phenoxybenzamine?

A

It is given to patients before surgical removal of tumours from the adrenal medulla.

It is used to manage prostate obstruction.

It is used to make the sphincter of the bladder relax.

20
Q

What is pheocromocytoma?

A

A tumour in the adrenal medulla and this results in the adrenal medulla over producing catacholamines.

21
Q

What is the detrusor muscle?

A

The bladder muscle.

22
Q

What are the 4 adverse effects of phenoxybenzamine?

A

Hypotension accompanied by reflex tachycardia.

Nausea.

Inhibition of ejaculation.

It is mutagenic.

23
Q

What is the mode of action of phentolamine?

A

It irreversibly inhibits alpha receptors by preventing the re-uptake of norepinephrine.

24
Q

Should phentolamine be given orally?

A

No, as it has poor uptake from the GIT.

25
Q

How does phentolamine affect the GI tract?

A

It is a muscarinic agonist meaning that it will increase GI effects such as GI motility etc.

26
Q

What is pseudo obstruction of the bowel?

A

When there is no obstruction, but the smooth muscle of the GIT does not work and this means food does not move along the GIT.

27
Q

What are the therapeutic uses of phentolamine?

A

Treatment of pseudo-obstructions of the bowel.

Treatment of hypotension.

It prevents dermal necrosis.

28
Q

How does phentolamine prevent dermal necrosis?

A

It blocks the alpha receptors that lead to vasoconstriction and this allows blood to flow to the extremities.

29
Q

What are the 4 adverse effects of phentolamine?

A

Postural hypotension.

Reflex tachycardia.

Arrhythmias.

Diarrhoea.

30
Q

What drug is used to reverse the effects of xylazine in large animals?

A

Tolazoline.

31
Q

What are the therapeutic effects of tolazoline?

A

Reverses the effects of xylazine.

Helps to visualise veins during arteriography.

Treats pulmonary hypertension in newborns.

32
Q

What are the adverse effects of tolazoline?

A

Cardiac arrhythmias.

GI stimulation.

33
Q

Will prazosin cause reflex tachycardia?

A

Its effects will be less pronounced.

34
Q

What are the 2 drugs that are related to prazosin?

A

Terazosin.

Doxazosin.

35
Q

Prazosin will affect what kind of receptors?

A

It is an alpha-1 antagonist.

36
Q

Tolazasine affects what kind of receptors?

A

It is an alpha receptor antagonist.

37
Q

Prozasosin is used to treat what conditions?

A

Hypertension.

Benign prostate hypertrophy.

38
Q

What happens when alpha-1 receptors are blocked?

A

There will be inhibition of vasoconstriction.

39
Q

Yohimbine will affect what kind of receptors?

A

It is an alpha-2 receptor antagonist.

40
Q

What are the effects of yohimbine?

A

It blocks pre-synaptic alpha-2 receptors in the brain and this favours the release of norepinephrine at the synaptic cleft.

41
Q

What is yohimbine used for?

A

To reverse the effects of xylazine and detomidine when these drugs are causing adverse effects.

42
Q

Yohimbine will be used in what animals?

A

Large animals.

43
Q

What drug is used to reverse the effects of xylazine and detomidine in small animals?

A

Atipamezole.

44
Q

What are the effects of alpha-1 blockers?

A

Management of pheochromocytoma.

Management of hypertension.

Treatment of benign prostate hypertrophy.

45
Q

What are the effects of alpha-2 blockers?

A

As a reversal agent for pre-anaesthetic medications.