Hypertension - Lecture 2 ( A1 blocker, A2 agonist, Beta Blockers) Flashcards
a1 stimulation results in….
vasoconstriction (reflex bradycardia)
Bladder sphincter contraction
Reduced Lipolysis
a2 stimulation results in….
decreased pre-synaptic NE release (reduced sympathetic outflow)
A1 blockers MOA
selectively block a1 receptors on smooth muscle cells of peripheral vasculature
Lowers BP via vasodilation, decrease PVR
Doxazosin (Cardura) Dose and Frequency
1-8mg, daily
Orthostasis…
when stand up BP drops but doesn’t go back up = dizziness
A1 Blockers Clinical considerations
No benefit in prevention of MI or CHD
“Last line”
A1 Blocker special considerations
2nd line agent in men with BPH
improves urine flow and decrease frequency with some drop in BP
ADE of A1 blocker
Orthostatic hypotension 1st dose syncope Dizziness Reflex tachycardia Peripheral Edema Sexual Dysfunction
a2 agonist MOA
stimulate a2 presynaptic receptors in the brain
increase inhibitory neuron acitivty decrease sympathetic outflow
Lower BP primarily via decrease PVR
Clonidine (Catapress) Dose and Frequency
0.1-0.8 mg, BID
Clonidine (Catapress - TTS) Dose and Frequency
0.1-0.3 mg, Weekly
Benefits of TTS
decreased rebound HTP with abrupt withdrawal
reduces side effects
A2 agonist Clinical considerations
Not 1st line
Avoid in pt with HF
A2 agonist possible indications
Resistant HTN (Clonidine) Pregnancy (Methyldopa)
ADE of A2 agonist
Significant CNS ADE Orthostatic Hypertension Dry mouth Depression Rebound HTN w/ abrupt stop
B1 Location
Heart
B2 Location
Lungs and Periphery
B1 receptor stimulation….
increase HR
increase Renin Secretion
B2 receptor stimulation…..
Smooth muscle relaxation
peripheral vasodilation
Skeletal muscle stimulation
Glycogenolysis & gluconeogenesis
Beta Blocker MOA
Competitively inhibit catecholamine NT at B1 and B2 receptor
reduce CO leading to decrease BP
Non-selective Beta blockers
B1 and B2 activty
Cardioselective Beta Blockers
B1 activity only
Non-selective Beta Blockers MOA
antagonist at B1/B2 receptors
Propranolol (Inderal) Dose and Frequency
160-480mg, BID
Propranolol long-acting (Inderal LA) Dose and Frequency
80-320 mg, Daily
Non-selective Beta Blockers Clinical Considerations
Avoid pt with reactive airway disease
Non-selective Beta Blockers Clinical uses…
Angina Post MI CV event prevention Atrial fibrillation/flutter supraventriclar arrhythmias migraine prophylaxis Tremors
Atenolol (Tenormin) Dose and Frequency
25-100, Daily
Which Beta blocker should someone with asthma take?
B1 blocker
Metoprolol Succinate (Toprol XL) Dose and Frequency
50-400mg, Daily or BID
Metoprolol Tartrate (Lopressor) Dose and Frequency
50-200mg, BID
B1 Selective Blockers Clinical indications
Angina Post MI CV event prevention Atrial fibrillation/flutter HF migraine prophylaxis
Carvedilol (Coreg) Dose and Frequency
6.25-50mg, BID
Carvediolol (Coreg CR) Dose and Frequency
20-80mg, Daily
Labetalol (Normodyne) Dose and Frequnecy
200-800mg,BID
Mixed A1/Beta Blockers
Carvediolol
Labetalol
Mixed A1/Beta Blockers Clinical Considerations
Carvedilol = mortality benefit in HF after stabilized
Labetalol = increased safety data in pregnancy, hypertensive emergency (IV)
Are Beta Blockers 1st line for uncomplicated HTN?
no
Who should use Beta Blockers?
pt with HTN plus compelling co-existing condition (HF, Post-MI, Angina)
B1 selective blockers
Atenolol
Metoprolol
Non-selective Beta Blockers
Propranolol
Beta Blocker Clinical Considerations
abrupt discontinuation can cause rebound HTN
Can cause fatigue
ppl with Asthma should avoid (use cardioselective if have to)
caution use with COPD
ADE Beta Blockers
Bronchspasm, worsen asthma
Cold hands, feet
Bradycardia
Fatigue
masked signs and symptoms of hypoglycemia except sweating
insomnia, sex dysfunction
Beta Blocker contraindications
SA or AV node dysfunction
Decompensated HF
Severe bronchospastic disease
Beta Blocker Drug interactions
Non-DHP CCBs
what to monitor when on Beta Blockers
BP
HR
BG if have diabetes
Signs and symptoms of asthma/COPD
What drug is Alpha-1 blocker?
Doxazosin
What drug is Alpha-2 Agonist?
Clonidine