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Pharm 2 > Antihypertensives (Alpha Agents) - Week 2 > Flashcards

Antihypertensives (Alpha Agents) - Week 2 Flashcards

1
Q

Effects of Alpha 2 receptor activation

A 
Inhibits neuronal firing in CNS and PeriphNS
- HoTN
- Bradycardia
- Sedation
- Analgesia 
Other organ functions
- Decreased salivation and secretions
- Decreased GI motility
- Inhibits renin release
- Inc GFR
- Inc Na and H2O secretion
- Dec insulin release
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2
Q

What type of drug is Phenoxybenzamine?

A

Nonselective alpha antagonist

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3
Q

Does Phenoxybenzamine bind reversibly to the receptor?

A

NO. It binds irreversibly and has a half-life of several days.

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4
Q

Uses of Phenoxybenzamine

A
  • long-term pre-op tx t control the effects of pheochromocytoma (chemical sympathectomy)
  • Relieve ischemia in PVD
  • Improve flow for BPH (flomax, papaflo, hytrin are now used more)
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5
Q

T/F Phenoxybenzamine reduces BP by reducing PVR.

A

True

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6
Q

Secondary increases in NE due to alpha 2 blocked can:

A

inc HR and CO

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7
Q

Does Phenoxybenzamine cross the BBB?

A

Yes

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8
Q

Side effects of Pehnoxybenzamine

A 
Sedation
Depression
Tiredness
Lethargy
HA
N/V
Postural HoTN
Tachycardia
Arrhythmias
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9
Q

What are the half life and duration of Phenoxybenzamine, and how is it administered?

A

Half-life: 24 hrs
Duration of action: 4 days
Route of admin: PO

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10
Q

What is Phentolamine?

A

mixed a1 and a2 antagonist

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11
Q

What is phentolamine used for?

A
  • HTN from pheochromocytoma
  • HTN from clonidine w/d
  • Erectile dysfunction
  • Tx extravasation of catecholamines
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12
Q

Half-life and onset of Phentolamine (IV and IM)

A

Half-life: 19 min
Onset IM: 15-20 min
Onset IV: immediate

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13
Q

Oral Alpha 1 antagonists

A

“-osin’s”
Prazosin, Terazosin, Doxazosin, Tamsulosin, Silodosin, Alfuzosin

Primarily used for BPH; only used for HTN if everything else has failed

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14
Q

Uses for Alpha agonists in anesthesia

A 
Premedication
Sedation
Anesthetic sparing effect
Regional anesthesia
Intrathecal, epidural, or caudal admin
Periph nerve block
Post-op analgesia
Analgesia of labor
Chronic pain
Prevent/tx drug w/d
Prevent/tx post-op shivering
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15
Q

T/F: According to the Cochrane Review, A2 agonists decrease overall mortality, cardiac mortality, and MI and are esp beneficial in vasc surg.

A

True

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16
Q

When using A2 agonists, the anesthetist should monitor for:

A

Excessive HoTN and bradycardia

17
Q

How does clonidine work?

A

Central acting Alpha 2 agonist that decreases the release of symp NT’s and inhibits renin release; has a much greater affinity for a2 than a1 (220:1)

18
Q

CV effects of Clonidine:

How does it affect the baroreceptors?

A

dec HR, BP, CO, and SVR

barorecptor reflexes are preserved

19
Q

Abrupt cessation of clonidine may lead to:

A

Rebound HTN

20
Q

From what do the s/s of clonidine w/d occur, and what are the s/s?

A

s/s are d/t NE

  • excessive HTN
  • Tachycardia
  • restlessness
  • Insomnia
  • HA
  • Severe nausea
21
Q

A pt is at risk for clonidine w/d if using clonidine for at least _____.

A

6 days

Because NE release has been inhibited, the body has increased the number of B1 and A1 receptors all over the body to catch any available NE. When the NE comes rushing back in, it attaches to all the receptors it can find.

22
Q

disadvantageous s/e of clonidine

A
  • drowsiness
  • dizziness
  • dry mouth
  • orthostasis
23
Q

What are cautions to consider w clonidine?

A
  • Severe coronary insufficiency
  • Conduction disturbances
  • Recent MI/CVA
  • CKD
24
Q

Why is epidural clonidine not recommended for preoperative period?

A

it creates HoTN

25
Q

Clonidine effects on anesthesia

A
  • dec prop requirements
  • alternative to N2O to
    • shorten induct time
    • attenuate adrenergic response to intub during inh anes
  • supplement regional blocks
26
Q

T/F: Dexmedetomidine is more selective to A2 over A1 than clonidine is.

A

True. Precedes has a 1620:1 affinity for a2:a1

27
Q

T/F: Precedex maintains resp stability in intub or extub pts and allows pts to be arousable and alert when stimulated because its sedation is a more natural sleep-like state.

A

True

28
Q

5 reasons Precedex is good for procedural sedation such as FOI and regional anesthesia administration

A
  • maintains spontaneous resp
  • sedation more like natural sleep
  • some analgesic effects
  • no amnesic effects
  • safe for non-anesthesia providers to use
29
Q

T/F: Although no studies have been conducted for safety of Precedex in children, it is useful in children who were inadequately sedated for procedures w other techinques.

A

True.

30
Q

Intra-op advantages of Precedex:

A
  • dec stress response
  • improved respirations
  • hemodynamic stability
  • improved efficacy of anes
  • inc recovery time
  • need fewer pain meds
31
Q

Post-op advantages of Precedex:

A
  • cuts opiate use in half

- dec post-op shivering

32
Q

Adverse effects of Precedex

  • Overall
  • Bolus
  • Infusion
A 
Over all
- N/V
- Fever
- Hypoxia
Bolus
- HTN
- bradycardia
infusion
- HoTN
33
Q

Precedex can cause clinically significant bradycardia and sinus arrest in what pt population?

A

Young, healthy pts w high vagal tone (or w rapid bolus)

34
Q

Do not give continuous precedex infusion to pts for > ______

A

24 hrs

35
Q

When using Precedex, exercise caution should be used in pts w:

A
  • advanced heart block

- severe ventricular dysfunction

36
Q

How does Methyldopa work?

A

It is metabolized to alpha-methylepinephrine in the CNS which acts at A2 receptors to decrease symp outflow

37
Q

Methyldopa is commonly used to treat HTN in what pt population?

A

Pregnant pts (usually in 3rd trimester)

38
Q

S/e of methyldopa

A
  • Sedation, HA, dizzy
  • Fluid retention (compounds fluid retention they already have)
  • orthostasis, bradycardia
  • hepatic necrosis
  • dry mouth, diarrhea, N/V
  • positive Coombs test, hemolytic anemia, bone marrow suppression (when used long term), impotence, rash

Pharm 2 (7 decks)

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