Beta blockers Flashcards
Mechanism of action?
b-1 adrenoceptors are mainly found in the heart while b-2 adrencoceptors are located in the smooth muscles of blood vessels &the airways.
effects related to the b-1 activity : they reduce the force of contraction &the velocity of conduction in the heart. (inotrope - &dromotrope -).
Mechanism of action, in terms of heart tropy?
The blockade of this pathway with beta-1 blockers results in decreased contractility (inotropy), decreased heart rate (chronotropy), increased relaxation (lusitropy), and decreased cardiac conduction times (dromotropy).
From explaining their mechanism of action, how are they able to help in certain cardiac issues (the indications)?
Beta blockers are able to relieve myocardial ischemia by reducing cardiac work &thus demand of oxygen. They are also able to improve prognosis in heart failure by protecting the heart from the effects of chronic sympathetic stimulation. They can also slow the ventricular rate in AF mainly by prolonging the refractory period of the AV node. Aside to that, they can restore correct sinus rhythm in SVT by breakign the self-perpetuating re-entry circuit that takes place in the AV node; origin of the SVT.
In hypertension, they induce a fall in blood pressure by a variety of means, one of which is reducing renin secretion.
Indications of beta blockers ?
- ischemic heart conditions; to improve symptoms &prognosis associated to angina ´ coronary syndrome.
- heart failure; first line option to improve prognosis
- AF; first line option to reduce ventricular rate &to maintain sinus rhythm.
- SVT; first line option in patients without circulatory compromise to restore sinus rhythm.
- Hypertension, generally prescribed when other medications are ineffective/inappropriate (Ca channel blockers, ACE inhibitors, thiazide diuretics)
Important AE of beta blockers ?
fatigue, headache, cold extremities, gastrointestinal disturbance (nausea), sleep disturbance (nightmares), impotence in men.
Important interactions?
Do not associate beta blockers with non-dihydropyridine Ca channel blockers (verapamil &diltiazem), this combination can cause heart failure, bradycardia &asystole.
Important cautions?
Beta blockers can cause life-threatening bronchospasm to asthmatic patients &should be avoided.
Beta blockers are generally safe in COPD, although it is prudent to choose a b-1 selective drug.
Beta blockers may alter heart function at the start of the treatment, they should be initiated in lower doses for patients with heart failure.
How are beta blockers taken?
Orally. Intravenous preparations are available for use when rapid effect is desired.
For once-daily drugs; bisoprolol, exact time isn’t important but equal intervals must be respected.
Name cardioselective blockers ?
Betaxolol, Acebutolol, Atenolol, Metoprolol, Bisoprolol, Nebivolol, Esmolol (strictly IV due to its short half life of about 9mns), Celiprolol.
Bathroom : Ceiling : Celipro, icebutt : Acebuto, Machine à laver etteint : Ateno, Toilette : Metopro, Mirror : Bisopro, Lavabo : Nebivo. Betaxo figure it out xD
Name non-selective beta blockers ?
Propranolol, Bucindolol, Carteolol, Carvedilol, Labetalol, Nadolol, Oxprenolol, Penbutolol, Pindolol, Sotalol, Timolol.
Agents specifically labeled for cardiac arrhythmia ?
Esmolol, Sotalol, Landiolol.
Agents specifically labeled for congestive heart failure?
Carvedilol, sustained-release Metoprolol.
Agents specifically labeled for glaucoma ?
Betaxolol, Carteolol, Levobunolol, Timolol, Metipranolol.
Agents specifically labeled for myocardial infarction?
Atenolol, metoprolol (immediate release), propranolol (immediate release), timolol, carvedilol (after left ventricular dysfunction).
protection secondaire post-idm : beta bloquant, ICE, statine, 2 anti-agregants plq.
Agents specifically labeled for migraine prophylaxis?
Timolol, propranolol
