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Flashcards in Prazosin Deck (28)
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1
Q

What is the trade name for Prazosin?

A

Minipress

2
Q

What is the formal drug classification for Prazosin?

A

Selective POST-synaptic alpha 1 adrenergic Antagonist; Antihypertensive

3
Q

What are the clinical uses for Prazosin?

A
  • essential hypertension
  • to decrease afterload in CHF
  • preop prep for patients with pheochromocytoma, who exhibit ST changes on ECG
  • Reduces Vasospasm in Raynaud syndrome
  • essential hypertension in pts with BPH b/c it reduces prostate size
  • Ischemic cardiomyopathy
4
Q

What receptors does prazosin work on?

A

Alpha 1

5
Q

Does prazosin block pre- or post- synaptically?

A

POST-synaptically (alpha 1 antagonist)

6
Q

What is the MOA of Prazosin?

A

Selective post-synaptic alpha 1 adrenergic antagonist resulting in vasodilating effects on both arterial and venous vasculature

7
Q

Does Prazosin work on the arterial or venous vasculature?

A

Both, BUT has 1,000 fold > affinity for alpha 1 receptors than for alpha-2 receptors

8
Q

What does the alpha-1 antagonism of Prazosin cause regarding vascular tone? Is there reflex tachycardia? What happens to venous return and CO?

A
  • Decreases SVR without causing reflex tachycardia or increases in renin activity
  • Vascular tone in both resistance and capacitance vessels is decreased, resulting in decreased venous return and CO
9
Q

Since Prazosin is selective for alpha-1 antagonism, what does this mean regarding alpha-2 receptors and NE release?

A

It leaves the inhibiting effect of Alpha-2 receptor activity on NE release intact, therefore it is less likely to evoke reflex tachycardia!!!!

10
Q

What does Prazosin do to the vasoconstrictor effects of NE and Epi?

A

Antagonizes their effects, thereby causing a decline in Peripheral Vascular Resistance, and venous return to the heart

11
Q

Tell me about the oral absorption of Prazosin

A

Has substantial 1st pass effect with oral intake, <60% bioavailability after oral administration

12
Q

Is Prazosin protein bound?

A

Highly bound to plasma protein

13
Q

How is Prazosin metabolized?

A

Via Demethylation and conjugation in the liver

14
Q

How is Prazosin eliminated?

A

Bile and Feces

15
Q

When does Prazosin take peak effect?

A

3 hours

16
Q

What is the plasma 1/2 life of Prazosin?

A

2-3 hours

17
Q

What is the elimination 1/2 time of Prazosin? but what is a condition that prolongs this?

A

3-4 hours, prolonged by CHF but NOT renal dysfunction

18
Q

What are the side effects of Prazosin?

A
  • Syncope with a sudden loss of consciousness with 1st dose, postural and dose related
  • Dizziness and Vertigo, Orthostatic Hypotension, Headache, Palpitations, fluid retention, drowsiness, weakness, anticholinergic effects, priapism
  • Dryness of the mouth, nasal congestion, nightmares, urinary frequency, lethargy and sexual dysfunction may occur
  • MAy cause bronchodilation
  • Palpitations, depression, dizziness, weakness
19
Q

What are serious side effects that may occur from Prazosin?

A
  • Pancreatitits
  • Hepatotoxicity
  • Systemic Lupus Erythematous
20
Q

What are the contraindications with Prazosin?

A
  • Hypersensitivity to Prazosin, Terazosin, or Doxazosin
  • Epidural anesthesia hypotension may be exaggerated due to drug induced alpha 1 blockade that prevents compensatory vasoconstriction in the unblocked portions of the body
  • Concommitant use of Beta Blockers could result in refractory hypotension during regional anesthesia due to potential blunted responses to beta 1 as well as alpha 1 agonists
21
Q

What pregnancy category does Prazosin fall under?

A

C- should only be used in pregnancy if the potential benefit justifies the potential risk to the mother or fetus

22
Q

What drug interactions with Prazosin cause an additive hypotensive effect?

A

Diuretic
Antihypertensive Agents
Phosphodiesterase-5 Inhibitor

23
Q

What drug interaction may occur between Prazosin and NSAIDS?

A

NSAIDS may interfere with the antihypertensive effect

24
Q

Which 2 drugs have decreased effectiveness when administered concurrently with Prazosin?

A

Clonidine

Alpha-methyl-dopa

25
Q

What is the initial PO dose of Prazosin?

A

1mg PO at bedtime, then titrated slowly to effect

26
Q

What is the maximum total daily dose of Prazosin?

A

20mg in divided doses

27
Q

What has Prazosin been shown to do regarding Lipid profiles?

A

Improves lipid profiles by lowering LDL levels while raising HDL levels

28
Q

As a secondary drug in combination with WHICH drug, has Prazosin proved to be effective for hypertension in young patients?

A

combination with a diuretic