Lecture 17 - Beta Blockers Flashcards
Indications?
hypertension, angina, heart failure, arryhtmias (AF, A flutter, SVT); thyrotoxicosis, migraine prophylaxis, anxiety
Beat adrenergic receptors and effect?
1: heart (tachycardia, increased contractility), 2: vessels (dilation) and bronchi (relaxation - adverse target), both: renin release
B1»»>B2 sensitivity?
metoprolol (lipid, hepatic), atenolol (polar, renal), celiprolol, esmolol
B1=B2 sensitivity?
propanolol (lipid sol., hepatic), nadolol
Mixed antagonists a & b?
labetalol, carvedilol
Beta blocker differences?
selectivity, elimination, half life, solubility, additional mechanisms
BP lowering mechanism?
unknown but: decrease HR, cardiac work, reset baroreceptors, renin inhibition, decrease symp. activity
Other CVS effects?
negative chronotropic: SA and AV node effects; Inotropic effects: negative (acute) and positive (chronic)
Other system effects?
respiratory B2 bloackage (asthma contraindication), reduce aqueous humour production, decreased glycogenolysis, thyrotoxicosis (decreased T4 -> T3), migraine
Adverse effects - drug?
asthma exacerbation, hypotension, bradycardia, negative inotrope, vasospasm, fatigue, impotence, hypoglycaemia, withdrawal
Drug interactions?
verapamil (negative chronotropic effect), diltiazem (mild), other BP lowering drugs, antidiabetics (hypoglycaemia risk)
Indications - angina?
metoprolol and atenolol, reduce heart rate and cardiac work, improve symptoms (same drugs for hypertension, 2nd/3rd line)
Indications - post MI?
decreased arrhythmias and ventricular rupture, increase cardiac remodelling
Indications - heart failure?
carvedilol (mixed beta antagonist), metoprolol or biso prolol (both B1 selective)
Mechanisms of treating heart failure?
decreased symp. tone (dec. HR, incr. sys filling, dec. O2 consumption), upregulation of B-receptors, modulation of post-receptor inhibitory proteins, attenuate apoptosis, improve baroreceptor function, improve LV remodelling
