IV - Adrenoreceptor Blockers Flashcards
Norepinephrine - primary transmitter at the symphathetic postganglionic neuron-effector cell synapse in most tissues.
Dopamine/Norepinephrine: Dopamine vasDILATES renal blood vessels while Norepinephrine vasCONTRICTS them.
Phenoxybenzamine is an adrenergic antagonist (alpha-nonselective). MOA: Irreversibly blocks Alpha adrenergic receptors (A1>A2)
Uses: Pheochromocytoma (pre-surgical). SE: Orthostatic hypotension, Reflex tachycardia. Notes: Forms covalent bond with Alpha receptors (effects last for several daya)
Phentolamine is an Adrenergic antagonist (alpha-nonselective). MOA: Reversibly blocks Alpha adrenergic receptors.
Uses: Pheochromocytoma (pre-surgical), Rebound Hypertension, Antidote to Alpha 1 agonist overdose. SE: Orthostatic Hypotension, Reflex tachycardia
Prazosin is an Adrenergic antagonist (alpha1-selective). MOA: Selectively blocks Alpha 1 adrenergic receptors.
Uses: Benign prostatic hyperplasia, Hypertension. SE: First dose orthostatic hypotension. Notes: Tamsulosin is most selective for prostatic smooth muscle
What is the pharmacologic advantage of Alpha 1 selectivuty?
Reflex tachycardia is less common and less severe.
ISOPROTERENOL is NOT a beta blocker.
It is a non selective beta agonist.
Propanolol is an Adrenergic antagonist (beta-nonselective). MOA: Blocks B1 and B2 receptors. Blocks sympathetic effects on heart and BP. Reduces renin release.
Uses: Angina prophylaxis, Hypertension, Arrhythmias, Migraine. SE: Bronchospasm, Erectile dysfunction, AV block, Heartfailure. Notes: Masks symptoms of hypoglycemia in diabetics. Carvedilol and Labetalol has combined Alpha and Beta blockade (may be used in pheochromocytoma)
Beta blockers with Intrinsic Sympathomimetic Activity.
Pindolol and Acebutolol
Beta blocker with longest half-life?
Nadolol = Nasa DOLO = longest half life
Beta blocker with shortest half-life?
Esmolol = ESMOL (small) = shortest half-life
Atenolol is an Adrenergic antagonist (beta 1 selective). MOA: Selectively blocks B1 rceptors. Blocks sympathetic effect on heart and BP.
Uses: Angina, Hypertension, Heart failure, Supraventricular tachycardia (Esmolol only). SE: Bronchospasm (less chance). Notes: Masks symptoms of hypoglycemia in diabetics.
Albutamol are sympathomimetic (beta 2-selective). MOA: Activates beta 2 receptors in bronchial smooth muscle. Causes bronchodilation.
Uses: Acute asthma attacks (drug of choice), Tocolysis for preterm labor. Notes: May precipaitate arrhythmias in patient with concurrent COPD and heart disease.
