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Adrenergic antags
UVa Med pharmacology block 2
| Question | Answer |
|---|---|
| Phenoxybenzamine | α1 > α2 irreversible adrenergic antagonist pheochromocytoma: pre-op, oral w/beta blocker and IV phentolamine or inoperable oral w/beta blocker slow onset, long lasting (3-4 days) via oral or IV admin spontaneous breakdown physiologic effects |
| Phentolamine | α1 & α2 reversible, competitive non-selective antagonist during surgery - protects vasculature short duration (19 min) by IV admin similar physiologic effects to phenoxybenzamine - vasodilation on VSMC, incr cardiac stim, incr GI tone/motility |
| Prazosin | α1 selective, competitive antagonist essential hypertension tx T1/2 approx 3 hrs by oral admin met'd by liver physiologic fx: vasodilation with decr reflex tachycard, 1st dose post hypotension, decr GFR, CNS |
| Terazosin | α1 selective, competitive antagonist essential hypertension tx, urinary retention (2ndary to BPH) T1/2: 12hrs by oral admin, Met'd by liver physiologic fx: vasodilation with decr reflex tachycard, 1st dose post hypotension, decr GFR, CNS |
| Propanolol | β1 & β2 adrenergic antagonist 1st gen hypertension, decr post-MI mortality, migraine prophylaxis T1/2 3-4hrs by oral admin met'd in liver phys fx: CV decr systolic, automaticity, incr PVR, decr renin, incr airway res, decr insulin, decr metab w/side fx |
| Nadolol | β1 & β2 adrenergic antagonist 1st gen hypertension T1/2 20-24hrs by oral admin not met'd phys fx: CV decr systolic, automaticity, incr PVR, decr renin, incr airway res, decr insulin, decr metab w/side fx |
| Timolol | β1 & β2 adrenergic antagonist 1st gen hypertension, WA glaucoma, decr post-MI mortality T1/2 4hrs by oral admin phys fx: CV decr systolic, automaticity, incr PVR, decr renin, incr airway res, decr insulin, decr metab w/side fx |
| Pindolol | β1 & β2 adrenergic antagonist 1st gen w/partial agonist activity hypertension t1/2 3-4hrs excreted by liver/kidney phys fx less severe than pure antagonist |
| Carvedilol | α1, β1, β2 antagonist third gen CHF, hypertension t1/2 7-10 hrs by oral admin excr in feces phys fx incr in CHF px's, CI: bronchospasm |
| Metoprolol | β1 competitive antagonist 2nd gen decr post-MI mortality, hypertension t1/2 3-4hrs IV or oral admin, met'd liver phys fx: like propranolol but less bronchoconstriction |
| Labetolol | α1,β1 antagonist, β2 partial agonist hypertension tx (very effective) t1/2 3-4hrs oral admin excr kidney/feces side fx: both types of antagonists(α1 & β1) |
| Atenolol | β1 selective antagonist 2nd gen hypertension (widely used pref'd by px's) t1/2 5-8hrs oral/IV admin excr kidney/feces phys fx: no sympathomimetic activity, does not penetrate CNS (good thing) |
| Acebutolol | β1 selective antagonist w/partial agonist activity 2nd gen hypertension tx, ventricular arrhythmia t1/2 3hrs oral admin side fx: decr HR/BP |
| Esmolol | Selective β1 antagonist 2nd gen supraventricular tachycardia, acute dissecting AA, crit ill px's t1/2 very short 10 min IV admin met'd by RBCs excr by kidney phys fx: no intrin sympathomimetic activity CI: overt heart failure |
| Betaxolol | Selective β1 antagonist 3rd gen WA glaucoma, hypertension, CHF t1/2 15 hrs topical/oral admin met'd by liver excr by kidney side fx: decr bronchoconstriction |
| Guanadrel | Non-selective adrenergic neuronal blocking agent (restricted use) Hypertension (w/diuretic) Phys fx: inhibit NE release in periphery - stored in place of NE, decr symp tone, BP, hypotension, H2O/NA+ reten, sexual dysfunction, opposes amphetamine/TCA |
| Reserpine | Non-selective adrenergic neuronal blocking agent (restricted use) Hypertension (w/diuretic) phys fx: blocks NE synth/storage->decr symp tone, BP, obtunded CV reflexes, parasymp predominance (bradycardia, diarrhea, miosis) sidefx: depression->suicide |
| How should one select different B-antagonists? | Based on pharmacology, medical problems of patient, and cost |
| How do neuronal blocking agents work? What is their overall effect? | Inhibit the release of norepinephrine by adrenergic nerves and thus have the same effect as the antagonists |
| What is the important difference between Prazosin and Terazosin? Why is the useful? | Terazosin has a longer half life (12 hours) as opposed to 3 hours which allows daily dosage for hypertension |
| What is special about Esmolol? When is it used? | B1 antagonist with SHORT half life (10 minutes) Used for critical patients that require rapid action/withdrawal, approved for supraventricular tachycardia |
| What are the bronchial properties of Propanolol? | increased airway resistance, may precipitate asthmatic attack |
| How is Labetalol used? What is special about it? What are its problems? | It is used as an anti-hypertensive; it is an antagonist at all alpha and beta receptors Problem is that it can have side effects of both types of antagonists |
| What is special about Acebutolol? | B1 selecting with INTRINSIC sympathomimmetic activity |
| What additional action does Carvedilol have? | Ca2+ entry blockade |
| How is phentolamine adminstered and where is it used? | IV and used in the operating room? |
| What drugs are used for essential hypertension? | Prazosin and Terazosin |
| How is Propanolol absorded? Where is it metabolized? Half life? | Orally, but first pass metabolism metabolized in liver 3 to 4 hours |
| What is Phenoxybenzamine's solubility and how is it administered? | Lipid soluble (crosses CNS, partially GI absorbed) IV or Oral administration (20-30% absorbed in oral) |
| Why does irreversible blockade occur slowly with Pheoxybenzamine? What is the time frame? | it is an alkylating agent and the chemistry takes time to develop in the order of 60 to 70 minutes; and lasts 3 to 4 days |
| When is Betaxolol used? What is its benefit? | B1 selective antagonist for opthalmic use; also hypertension May lessen bronchoconstriction side-effects that occur in some patients using B-antagonists for glaucoma |
| What are some important differences between Prazosin and the a1/a2 antagonists? | Little or no GI function (no a2 blockade), rarely produces sexual dysfunction CNS side effects: drowsinees, dizziness, fatigability (probably due to central a1 blockade) |
| What therapeutic distinction for hypertension and angina do the different b-antagonists have? | NO DISTINCTION in treatment of these two disorders is apparent |
| T or F: Metoprolol is superior than Carvedilol for CHFmortality | FALSE Multi-center studies show that Carvedilol has a slightly lower mortality rate |
| How in Pindolol used? What is its benefit? | Used as an anti-hypertensive Withdrawal effects less severe than pure antagonists, but still present |
| What is the main difference in the site of action of adrenergic agonists versus antagonists? | Agonists tend to have actions at BOTH alpha AND beta sites, whereas the antagonists are classified as alpha OR beta |
| In what stage of the micturition stage are a1 receptors most important? What part of this stage do they affect? | a1 are most important in the filling phase, they contract the bladder neck and urethra |
| What drug(s) is/are used for urinary retention? Why? | Terazosin - a1 blockage reduces resistance to urinary flow |
| What are the two uses of Timolol? | Hypertension Glaucoma by topical application **reduces production of aqueous humor * Also reduces post-MI mortality. |
| What drug(s) are used to treat Pheochomocytomas? How do their uses differe? | Preoperatively: oral phenoxybenzamie with IV phentolamine during surgery *Always used in conjunction with a Beta blocker. Chronic: inoperable tumors treated with phenoxybenzamine *Always used in conjunction with a Beta blocker. |
| What are the metabolic properties of Propanolol? | blockade of catecholamine effects of insulin release and B effects to increase metabolism in liver, fat, and skeletal muscle |
| What is specil about Atenolol? | B1 with no sympathomimetic activity Hydrophilic so does not penetrate CNS GOOD |
| Which types of antagonists are very effective at treating cardiovascular diseases? | B antagonists |
| What drugs are used for glaucoma whose mechanism is a decrease in aqueous humor production? | Alpha AGONISTS - Epiphenrine (a and B) - Phenylephrine (a) Beta ANTAGONISTS - Timolol (B1 and B2) - Betaxolol (B1) |
| At what receptor does Metoprolol act? How is it different and similar to Propanolol? | Competitive antagonist at B1 (B2 requires high doses) Same action as Propanolol, except broncho actions require high dose Toxicities are same as propanolol, except broncho requires high doses Absorption similar to propanolol |
| What drugs specifically have been show to reduce mortality after an MI? | Propanolol, Timolol, Metoprolol |
| What are some undesirable side effects of adrenergic antagonists? | -postural hypotension (alpha 1 normally constricts vessels) - sedation/depression - increased GI motility (alpha 2 normally decreases motility) - decreased sexual function (alpha 1 block) - sodium retention (decreased renal flow --> Renin) |
| What are the therapeutic uses of B-antagonists? | - Cardiovascular disease - Reduction of mortality after MI - Reduction of tachycardia in hyperthyroid and pheochormocytoma patients (Beta1 usually increases HR) - Prophylaxis of migranes - Wide angle glaucoma - Performance anxiety |
| What drugs are used for the treatment of glaucoma whose mechanism is INCREASED OUTFLOW? | Cholinergic Agonists - Pilocarpine - Carbachol Acetylcholinestirase Inhibitors - Physostigmine - Isoflurophate |
| What is Nadolol? | same as propanolol but with longer half live (20 to 24 hours) |
Created by:
sam.mrosenfeld
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