Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Regulation of Body Function > Alpha blockers and calcium channel blockers > Flashcards

Alpha blockers and calcium channel blockers Flashcards

1
Q

the two classes of adrenergic receptors and their affinites

A

alpha and beta
alpha: NE > epinephrine&raquo_space; isoprotenol
Beta: Isoprotenol > epinephrine > NE

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Alpha 1 receptors

A

postsynaptic, vasoconstriction, (veins and arterioles) inc BP
alpha 1 a = prostate, VSM
alpha 1 b = VSM
alpha 1 d

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

alpha 2 receptors

A 
pre and post synaptic 
inhibit norepinephrine and insulin release 
alpha 2 a 
alpha 2 b 
alpha 2 c
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

alpha 1 antagonists

A

Doxazosin, prazosin, terazoin (block all alpha 1 subtypes)
vasodilatation, hypotension
Tamsulosin (alpha 1 a specific), so helpful in reducing prostate size when increased whereas doxazosin will also have an effect on BP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

alpha 2 antagonism

A

not used clinically

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

combined alpha 1 and 2 antagonists

A

phenoxybenzamine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

alpha blockers indications

A

hypertension
- essential hypertension
useful in combination therapy (e.g. diuretic, ACEi and alpha blocker)
- pheochromocytoma –> alpha blockers useful here, this is also a tumor of the SNS usually in the adrenal gland, where too much adrenaline and noradrenaline produced treatment is surgery but perioperativly use alpha-blockers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Doxazosin

A

reversible alpha blockade alpha1&raquo_space;» alpha2
- vasodilator: blocks tonic sympathetic activity on resistance vessels
- reduce prostatic symptoms
start low dose an titrate
od
oral
first pass hepatic metabolism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Why aren’t prazosin and terazosin as good as doxazosin?

A

prazosin has very short half life and so needs to be taken twice to 3x daily, and terazosin has slightly more side effects than D

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

alpha blockers adverse effects

A 
hypotension - give first dose at night 
Dizziness 
Lassitude (tiredness) 
Nasal stuffiness 
Dry mouth 
Urinary incontinence in women
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

rarely used alpha blockers: phenoxybenzamine

A 
oral 
irreversible alpha blocker antagonist alpha1 > alpha2 
blocks serotonin receptors 
used in pheochromocytoma
used preoperatively  
marked side effects 
- postural dec BP, tachycardia 
- nasal stuffiness 
- CNS
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Rarely used alpha blockers: phentolamine

A

poorly absorbed, give in IV
competitive antagonist alpha 1 = alpha 2
increase NE release
5HT antagonist
- limited use, hypertensive crisis e.g. phaeco and cocaine OD

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

combined alpha and beta blocker: labetalol

A

reversible antagonist
hypertension in pregnancy
phaecochromocytoma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

combined alpha and beta blocker: carvedilol

A

also antioxidant properties

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

specific alpha blockers: tamsulosin

A 
oral 
competitive antagonist 
alpha1a and d 
Relax bladder and prostate smooth muscle 
less postural hypotension 
long t1/2, given once daily
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Calcium channel blockers - indications

A

hypertension (vasodilation)
angina (decreased cardiac work, vasodilatation)
arrhythmias (SVT tachcyarythmias)
- atrial fibrillation / flutter rate control
- SVT termination
Vasospasm
e.g. raynauds phenomenon, cerebral vasospasm

17
Q

Calcium channel blocker mechanism and selectivity

A

block voltage gated L type Ca2+ channels - cardiac and smooth muscle (decrease arteriolar smooth muscle tone, decrease peripheral vascular resistance, decrease BP)
cardiac cells –? decrease sinus node rate and AVN transmission
some selectivity
- resistance vessels
- Myocardium
- conducting tissue

18
Q

The dihydropyridines

A

e.g. Nifedipine –> are pure vasodilators, useful in lowering BP and in angina as they also dilate coronary arteries. resistance vessels (flushing, headaches, oedema)

19
Q

e.g. of a benzothiazepine

A

diltiazem = in between effects

20
Q

phenylalkylamine example

A

verapamil
very little effect on calcium channels in resistance vessels, its mechanism on calcium channels in conducting tissues
- cardiac tissue = heart block, negative inotrope
constipation because peristalsis in bowel inhibited

21
Q

Ca2+ blocker pharmacokinetics

A

oral = all
IV preparations = diltiazem and verapamil
Significant first pass hepatic metabolism: cytochrome P450 system
Variable half life:
nifedipine/ diltazem few hours so do slow release capsule
amoldipine = long in days

22
Q

Nifedipine

A 
hypertension 
vasospasm e.g. raynauds 
Oral, do not use sublingual = too intense 
SR tablets 
hepatic metabolism protein bound 
renal excretion 
oedema, flushing, headache 
* no effect on conducting system of the heart therefore no use in slowing e.g. atrial fib
23
Q

Diltiazem

A 
effects on conducting tissue therefore can slow HR and vasodilator activity 
Angina, hypertension, tachyarrythmias 
Oral and IV 
hepatic metabolised, fecal excreted 
Various delayed release preparations 
oedema, flushing, headache, bradycardia
24
Q

verapamil

A 
tachyarrythmias (SVT, AF rate control) 
hypertension 
Oral and IV 
hepatic metabolism + renal excretion 
decreased bioavailability 
S/E - bradycardia, -ve inotrope, constipation
25
Q

verapamil blocker interactions

A

do not use with beta blockers - both too potent, can cause forms of heart block
care with statins,
e.g. simvastatin
cytochrome P450
also inhibits P glycoproteins which excrete drugs out of system e.g. digoxin so this can cause digoxin toxicity

26
Q

niche market: clevidipine

A

acute hypertension
parenteral
IV infusion with lure, and after measuring BP at the same time titrate
- hydrolysed by plasma esterase’s, rapid onset and offset of action

27
Q

Why in a patient with asthma and stable angina would you use calcium channel blockers

A

beta blockers can cause exacerbation of asthma

28
Q

Conclusion Alpha blockers use when?

A

3rd line use for hypertension
combination therapy with ACEi and diuretic
consider if concurrent potassium

29
Q

conclusion: Ca channel blockers use when?

A

2nd or 3rd line use for hypertension
combination therapy with ACEi and diuretic
use if concurrent angina
rate and SVT control

Regulation of Body Function (31 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions