Beta Blockers Flashcards
Propranolol
Nonspecific Beta-adrenergic Receptor Antagonist
Uses;
- Tx HTN
- Ventricular dysrhythmias
- Myocardial Infarction/Ischemia
- Angina
- lower HR to perfuse CA
- hypertrophic cardiomyopathy
- pheochromocytoma
- migraine headache
MOA;
- antagonist at both B1 and B2 equally
- B1 block causes decreases HR, myocardial contractility and Cardiac output and oxygen sparring effects (making it effective for myocardial ischemia)
- B2 block causes an increase in coronary and peripheral vascular resistacne
Dose; 0.05mg/kg or 1 - 10mg (1 mg q 5 min)
(Test dose 0. 25 - 0.5 mg then titrate to less than or equal to 1 mg/min for desired effect)
Pharmacokinetics; highly lipid soluble can cross the BBB -E1/2t; 2 - 3 hours -Vd; 3.9L/kg -Pb; 90 - 95%
extensive hepatic 1st pass- effect (90 - 95%) and metabolized into and active metabolite 4-hydroxypropranolol
Side Effects;
- bradycardia
- bronchospasm
- hypoglycemia
- CHF
- sedation/drowsiness
- abrupt withdrawal can cause rebound angina
- decreases clearance of Amide LA
- must get BB before surgery
Contraindicated;
- severe bradycardia
- asthma
- COPD
- Cardiogenic shock
- uncompensated cardiac failure
- heart block
Caution;
- DM
- peripheral vascular disease (B1 selective is better)
- pregnancy last 2 trimesters
Esmolol
- Beta-adrenergic receptor antagonist
- B1 cardio-selective
- Class II anti arrhythmic agent
Uses;
- Blunt SNS response with intubation
- Tx of tachycardia and HTN in the intra/post-op period
- SVT/A-fib/ A-flutter
- Controlled hypotension
MOA;
-competitively antagonizes B1 receptors; decreasing HR, contractility (inotropy) and cardiac output
Dose; 0.5 mg/kg or 50 -300 mcg/kg/min
(5 -10 mg IV (max total; 80mg))
Pharmacokinetics; Rapid onset short DOA -onset; 2 min -peak 5 mini -E1/2t; 9 min -DOA; 10 min -Vd;High -Pb; 55%
metabolized by plasma esterase
2% unchanged in urine
Side Effects;
- bradycardia/ asystole
- heart block
- chest pain
- hypotension
- bronchospasm
- pulmonary edema
- dyspnea
- N/V
- urinary retention
- pain on injection
- dizziness
- confusion
- agitation
- headache
Contraindicated;
- hypersensitivity
- bradycardia
- heart block
- cardiogenic shock
- asthma
- hypotension
- pregnancy (2nd and 3rd trimester)
Labetalol
Competitive adrenergic Alpha1 Beta1 and Beta2 receptor antagonist
Uses;
- Blocks SNS response to noxious stim (tracheal intubation)
- Tx HTN crisis (pheochromocytoma, w/drawl from clonidine)
- Tx Angina
- Improves myocardial oxygen supply and demand balance preoperatively
- Tx SVT
- Pre-eclampsia
- Controlled hypotension in pt where elevated HR is detrimental
MOA;
- blocks A1, B1 and B2 receptors; beta to alpha block 7:1 ratio
- blocks SA and AV node action potentials
- decreases HR, BP, and SVR; CO unchanged
Dose; 5 -20 mg IV (usually 5 mg)
q. 5 - 10 min
(max total dose; 300 mg)
Pharmacokinetics;
- max drop in BP takes 5 -10 min
- E1/2 5 - 8 hrs (longer in liver disease and shorter in pregnant women; 1.7 hrs)
- Vd; 3 -16 L/kg (mean 10 L/kg)
- Pb 50%
highly metabolized by the liver
(can cause liver dysfunction; watch LFT with chronic use)
5% excreted unchanged in urine
Side Effects;
- bronochospasm
- orthostatic hypotension
Contraindicated;
- asthma
- COPD
- cardiogenic shock
- heart block
- uncompensated HF
- severe bradycardia
Metoprolol
Selective B1 antagonist
Uses;
- Tx HTN & Heart disease
- management of HTC, CAD, Heart Failure, Angina
- Pre-op to reduce M&M in surgical patients with risk factor for CA
MOA; selectively binds to B1 receptors blocking effects of catecholamines and other B1 agonist; causing; decreased HR, myocardial contractility, and myocardial 02 demand
-B2 effects (bronchodilation and vasodilation) should remain intact but as dose increases B1 selectivity decreases
Dose; 1.25 - 5 mg q 2-3 min up to max of 15 mg (IV)
Pharmacokinetics; lipid soluble; can cross BBB -E1/2t; 3 - 4 hrs -1/2 life 3 - 7 hours -Pb;10%
PO has 50% first pass metabolism
Metabolized by CYP2D6 (poor metabolizers have higher plasma concentrations; but seems to have no effect on the safety/ tolerability of drug)
Excretion less then 5% unchanged from PO dose
Side Effects;
- life threatening bradycardia/asystole
- N/V
- diarrhea
- ab pain
- Higher dose can cause bronchospasm and heat failure
Contraindications;
- hypersensitivity
- 2nd/3rd degree heart block
- congestive heart failure
- low systolic BP (<100)
- low HR (<60)
- acute bronchospasm
Relative Contraindication
-long term use in DM
Caution;
-asthma
