Pharm REVERSE -adnrenergic antagonists Flashcards
drugs that disrupt the synthesis, storage or release of norepinephrine
What is the mechanism of adrenergic neuron blockers?
1) Guanethidine
2) Guanadrel
3) Reserpine
Which drugs are Adrenergic neuron blockers? (3)
Inhibits norepinephrine release and depletes neuronal amine stores
What is the mechanism of Guanethidine and Guanadrel? (2)
Severe hypertension
What is the therapeutic use of Guanethidine and Guanadrel?
Guanethidine is a polar compound that does not enter the CNS
What is the difference between Guanethidine and Guanadrel?
NET - therfore they are inhibited by tricyclic antidepressants that inhibit NET
How are Guanethidine and Guanadrel taken up into the cell?
Many side effects: orthostatic hypotension, interferes with sexual function, diarrhae, muscle weakness, edema
What are the side effects of Guanethidine and Guanadrel?
It inhibits he vesicular monamine oxidase transporter 2 (VMAT2) therby inhibiting the synthesis of norepinephrine
What is the mechanism of Reserpine?
diffusion (does not need VMAT2)
How does Reserpine get into the cell?
treats essential hypertension - rarely used
What is the therapeutic use of Reserpine?
Many CNS side effects, depression, suicide, sedation
Other side effects: diarrhae, orthostaic hypo-tension, increased gastric acid secretion
What are the side effects of Reserpine?
Slow onset and Long acting
What is Reserpine’s length of onset and how long does it last?
Agents produce their major actions by inhibiting alpha and beta receptors. Both exogenously administered as well as endogenously released catecholamines are blocked
What is the mechanism of adrenergic receptor blockers?
1) Phenoxybenzamine
2) Phentolamine
3) Prazosin
4) Tamsulosin
What drugs are alpha adrenergic receptor antoganists? (4)
irreversible inhibition of a1 and a2
Phenoxybenzamine
Irreversible antagonist via covalent bonding with receptor. New receptors need to be synthesized, so it is very long lasting
What is the mechanism of Phenoxybenzamine?
produces vasodilation proportional to the degree of sympathetic tone
What is the effect of Phenoxybenzamine?
Competitive reversible antagonist of a1 and a2
phentolamine
Therapies:
1) pheochromocytoma
2) To reverse or shorten the duration of soft-tissue anesthesia produced by combined local anesthetic and sympathomimetic
Phenoxybenzamine
Therapies:
1) hypertension
2) pheochromocytoma
3) to reverse or shorten the duration of soft tissue anesthesia produced by combined local anesthetic and sympathomimetic
Phentolamine?
Side effects:
1) tachycardia and salt/water retention (edema)
2) Orthostatic hypotension
phenoxybenzamine and phentolamine
competitive blocker of a1 receptors
Prazosin
Effects:
1) minimal tachycardia
2) decreases vascular tone in resistance (arterioles) and capacitance (veins)
3) produce favorable lipid profile: low LDL, high HDL
Therapys:
1) hypertension
2) short-term treatment of congestive heart failure (because of preload and afterload reducing agent)
3) Benign prostatic hyperplasia (BPH) - relaxes a1 mediated contraction of prostate and bladder neck that contributes to resistance to urine flow
Prazosin
Side effects
1) “first dose” phenomenon - hypotension and syncope 30-90 minutes after first dose
2) presistent orthostatic hypotension
3) salt and water retention (edema)
prazosin
a1 receptor antagonist with ome selectivity for a1A versus a1B (favors a1A receptor blockage in prostate)
Tamsulosin
Therapeutic use:
Effective for treatement of BPH with little effect on blood pressure
Not approved for treatmenet of hypertension
Tamsulosin
1) Propranolol
2) Timolol
3) Metoprolol
4) Atenolol
What are the non-selective beta adrenergic receptor antagonists?
Competitive reversible blockade of both B1 and B2 receptors
Propranolol and Timolol
Therapeutic use:
Hypertension
Angina
cardiac arrhythmias due to excess catecholamines or that respond to a reduction in heart rate/AV conduction velocity
Acute myocardial infarction
migraine prophylaxis
Propanolol
Side effects
Cardiac depression, bradycardia/heart block
May increase airway resistance
Mask sympoms of hypoglycemia
sedation, impotence, nightmares
Propranolol
Patients with shouldn’t recieve what drug:
Asthma
CHF
bradyarrhythmias, AV block
insulint-dependentdiabetes prone to hypoglycemic episodes
hypotension
vasopastic angina
Propranolol
Therapeutic use:
Similar to propranolol along with treatment of wide angle glaucoma
Timolol
Competitive, reversible B1 receptor blocker
Metoprolol
Therapeutic use:
Similar to propranolol - also used to treate heart failure
metoprolol
B1 receptor antagonist
Atenolol and metoprolol
Similar to propranolol (except for migraine prophylaxis)
Atenolol
Therapys
Essential hypertension and hypertensive emergencies
Labetalol
Competitive antagonist of a1 receptor and both B receptors (non-selective)
Labetalol and Carvedilol
1) anti-oxidant properties and anti-inflammatory effects
2) blocks L-type calcium channels at higher doses
Carvedilol
Therapeutic use:
1) CHF
2) Hypertension
3) Acute MI
Carvedilol
