Pharmacology - chapter 7 - Adrenergic antagonists Flashcards
phenoxybenzamine therapeutic uses?
pheochromocytoma, raynauds disease, frostbite, acrocyanosis.
Phenoxybezamine?
Irreversible & noncompetitive inhibitor of alpha-1 and alpha-2 receptors.
Phentolamine?
competitive block of alpha-1 & alpha-2 receptors used to treat hypertensive crisis.
Prazosin, Terazosin, Doxazosin, Tamsulosin and Alfuzosin ?
Selcetive competitive blockers of the lpha-1 receptor.
Tamsulosin & alfuzosin therapeutic uses?
Benign Prostatic hyperplasia
Prazosin, Terazosin and Doxazosin therapeutical use?
used to treat hypertension. By inhibiting alpha-receptors these drugs inhibit vasoconstriction = vasodilates. They also bind alpha receptors in adipose tissue and in liver, improving lipidprofiles and glucose metabolism in hypertensive patients.
What is “first-dose” effect?
E.g. Prazosin, terazosin and doxazosin may produce a orthostatic hypotensive response when the first dose is administered.
How to avoid “first-dose” response?
lower the first dose to 1/3rd or 1/4th of normal dose, and give drug at bedtime.
5alpha-reductase?
convert testosterone to dihydrotestosterone
Finasteride and dutasteride?
5 alpha-reductase inhibitors used to treat benign prostatic hyperplasia
A humongously horribly disastrous sideeffect of Finasteride and duasteride?
sexual dysfunction
Yohimbine?
Found as a component of the bark of the yohimbe tree. It’s a selective competitive alpha2-blocker. Works at the level of the CNS to increase sympathetic outflow.
All clinically available beta blockers are… ?
competitive antagonists
with exception of labetalol and carvediol, the name of all beta blosker end in …..?
“-olol”
Propranolol?
Beta-1 and beta-2 blocker
Effects of propanolol? 1 cardiovascular 2 respiratory 3 kidney 4 glucose
1 cardiovascular - lowers CO with negative iono-and chronotrophic effects. Prevents beta-2 mediated vasodilation = vasoconstriction.
2 respiratory - bronchoconstriction
3 decreased renal perfusion increses Na-retention.
4 glucose - beta-blockade leads to decreased glycogenolysis and glucagon secretion.
Conditions where you never treat with propranolol?
Asthma or COPD patients.
beta blockers in asthmatic diabetes patient?
use cardioselective betablockers
Drugs that inhibit or interfere with propranolol?
cimentidine, fluoxetine, paroxetine and ritonavir
drugs that stiulate or induce metabolism of propanolol?
barbiturates, phenytoin and rifampin
Timolol and nadolol?
Noselective beta antagonists that are more potent than propanolol.
Beta blockers and glaucoma?
Beta blockers are effective in treating glaucoma. The decrease the intraocular pressure by lowering the secretion of aqueous humor by the ciliary body.
Acetubulol, atenolol, metoprolol, bisoprolol, betaxolol, nebivolol og esmolol?
Beta1 selective antagonists.
beta-1 cardioselectivity and dose-relationship?
cardiospecificity is most pronounced at low doses, and lost with increased doses.
pindolol and acebutolol?
beta-1 antagonists with slight intrinsic agonist activity.
Labetalol and carvediol?
antagonists of both alpha and beta adrenergic receptors. Good drugs for treating hypertensive patients for whom increased TPR is undesirable.
Reserpine?
plant alkaloid that block Mg/ATP-dependent transport of biogenic amines, norepinephrine, dopamine and serotonine.
Guanethidine?
blocks release of stored norepinephrine as well as displacing norepinephrine from storage vesicles.
Cocaine?
blocks reuptake of epinephrine, norepinephrine, serotonine and dopamine by inhibiting monoamine reuptake and thereby potentiating their effects.
Drug of choice in pheocromocytoma?
Phenoxybenzamine - a nonselective noncompetetive alpha blocker that manage the hypertesive crisis that can be seen in pheocromocytoma.
The only irreversible alpha blocker out there is …. ?
phenoxybezamine
selective alpha1 blockers are primarily used in these to conditions?
hypertension & BPH
drugs would be prazosin, doxazosin, terazosin and tamsulosin
Where do these two drugs work?
1 Yohimbine
2 Mirtazapine
1 Yohimbine is an alpha2 blocker
2 Mirtazapine is also an alpha2 blocker, frequently used in treating depression. Adverse effect with miratazapine is weight gain.
Three conditions where you avoid betablockers?
1 Diabetes
2 Asthmatics
3 People with pripheral vascular diseases, esp. prinzmetals angina.
Which beta blockers are beta1 selective?
All drugs that start with the letters A through M are beta1 selective.
what beta blocker have the strongest sedative effect?
propranolol
why add diuretics and beta blockers to patients recieving alpha1 blockers?
beta blockers to counter a reflex tachycardia
diuretics because of increased RAAS activity
why are alpha blockers used in BPH?
symtomatic management of BPH by relaxing the trigone sphincter. A bonus is that the alpha blocker treat the comorbid condition of hypertension
Three main places where beta1 receptors are located?
1 Heart
2 Kidney
3 Eye(aqueous humor production)
What is the best drug to counter act a overdose of beta blockers?
Glucagon, due to the fact that glucagon interacts with Gs protein and increases intracellular cAMP.
Beta blocker that do not have a sedative effect?
Atenolol
The only beta blocker that can be used in thyrotoxicosis?
Propranolol, because it is the only beta blocker that inhibits deiodinase - conversion of T4 to T3
Pilocarpine, echothiophate and timolol are all used to treat…. ?
Closed angle glaucoma. Pilocarpine and echothiophate are cholinomimetics that produce miosis, whereas timolol make beta1 blockade that reduce the production of aqueous humor.
alpha1 selective agents: first dose precautions?
First dose should be small and taken right before bed, due to the fact that selective alpha1 blockers are associated with an exaggerated orthostatic hypotensive response(pooling of blood in the veins reduce the venous return).
Three beta blockers with partial agonist activity(ISA)?
1 Acebutolol
2 Labetalol
3 Pindolol
