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27 Cards in this Set
- Front
- Back
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Therapeutic uses of alpha blockers? (3) |
1. Pheochromocytoma (tumors that secrete catecholamines) 2. Primary hypertension 3. Benign prostatic hyperplasia |
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1. MOA and 2. Duration of action of prazosin?
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1. It is a reversible competitive antagonist. It dissociates from a receptors. More selective of a1 than a2.
2. Duration of action is based on half-life of the drug. |
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1. MOA and 2. duration of action of Phenoxybenzamine?
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1. Irreversible a-receptor antagonist. Forms reactive ethyleneimonium intermediate that covalently binds to apha receptor.
2. Duration of action depends on synthesis of new alpha receptors. |
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What happens if you give a patient an alpha blocker and epinephrine at the same time?
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The alpha blocker would cause hypotension (blocks a1 - negative inotrope and vascular SM dilates).
The epinephrine would cause further hypotension due to further dilation of skeletal muscle blood vessels (called "epinephrine reversal") |
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1. MOA and 2. Therapeutic uses of phentolamine?
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1. Non-selective alpha receptor antagonist. Also inhibits serotonin. May be agonist of H1 and H2 histamine receptors.
2. Pheochromocytoma and ED (intracavernosa injection ew ew ew) |
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1. MOA and 2. Therapeutic use of phenoxybenzamine?
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1. Irreversible a1 selective blocker. 14-48 hours. Inhibits reuptake of norepinephrine, blocks histamine, acetylcholine and serotonin receptors.
2. Pheochromocytoma |
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Side effects of phenoxybenzamine?
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Postural hypotension and tachycardia.
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Symptoms of pheochromocytoma?
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Tachycardia, anxiety, headaches, intermittent or sustained hypertension, palpitations, sweating |
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Define: pheochromocytoma
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Tumors - usually found in adrenal medulla. Causes excessive secretion of norepinephrine and epinephrine. Diagnosed by serum assay of catecholamine level. |
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1. Therapeutic use and 2. Side effects of prazosin?
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1. Hypertension and mild benign prostatic hyperplasia
2. Postural hypotension common (first dose, take laying in bed for elderly) |
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Locations of a1 receptor subtypes?
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a1A - prostate and urethra a1B - CNS, spleen, lungs, arteries and veins a1D - Detrusor muscle of bladder and spinal cord |
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1. MOA and 2. Therapeutic use of Tamsulosin?
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1. Selective of a1A and a1D, with a greater effect on prostate SM than vascular SM.
2. Benign prostatic hyperplasia |
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Side effects of tamsulosin?
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Little effect on blood pressure, but causes lots of dizziness. |
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Define: benign prostatic hyperplasia
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Age related enlargement of prostate that causes weak urine flow, leakage, noctura and urgency. Acetylcholine M3 receptor activation causes urination. |
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Affect of beta blockers on heart? |
Negative inotropy and chronotropy Slowed AV node |
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Affect of beta blockers on vasculature? |
Opposes B2 mediated vasodilation |
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Affect of beta blockers on respiratory tract? |
Opposes B2 mediated bronchodilation |
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Affect of beta blockers on metabolic/ endocrine? |
Inhibits lipolysis and glyconeogenesis Increased VLDL and decreased HDL cholesterol |
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Define: first past effect/ first pass metabolism |
When drugs, such as some beta blocker, are metabolized in the liver first before entering systemic.
This causes variability in the drug concentration so dose varies per individual. |
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1. MOA and 2. Therapeutic uses of propanolol? |
1. Non-selective beta blocker. Extensive first-pass metabolism in liver, so IV doses must be very small compared to oral.
2. Hypertension, angina, migraine prophylaxis, essential tremor, decrease sudden death after MI, severe hypothyroidism |
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Adverse effects of propanolol? (3) |
1. Fatigue 2. Depression and nightmares (passes BBB) 3. Bradycardia |
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1. MOA and 2. Therapeutic uses of metoprolol? |
1. Selective antagonist of B1 (located at heart)
2. Treatment of hypertension and tachycardia after (myocardial infarction)
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Which beta blocker (metaprolol or propanolol) is preferred for treatment of hypertension, and why? (2)
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Metaprolol.
1. Is selective for B1 receptor, whereas propanolol is non-selective. Therefore, less side effects. 2. B2 receptor may also play a role in recovery from hyperglycemia in liver, so metaprolol is preferred for diabetic patients. |
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1. MOA and 2. therapeutic use of acebutulol? |
1. B1 selective antagonist with partial B1 agonist properties. Weak membrane stabilizing activity. Low oral bioavailability.
Partial agonist = less likely to have bradycardia and less likely to alter plasma lipids.
2. Hypertension, angina |
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Define: local anesthetic membrane-stabilizing effect |
Local anesthetics block sodium channels in neurons to prevent action potentials. |
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1. MOA and 2. Use of labetelol? |
1. Labetelol is a racemic mixture of two pairs of chiral isomers. Both isomers are a1 selective blockers. The other is a non-selective b blocker with some b2 agonist activity.
Hypotension as a SE is accompanied less by tachycardia than other beta blockers due to B blockage which prevents elevation of heart rate.
2. Hypertension, including hypertensive emergency and during pregnancy. |
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What are the clinical uses of beta blockers? (7) |
1. Hypertension (often used with diuretic of vasodilator) 2. Ischemic heart disease (angina) 3. Cardiac arrhythmias 4. Glaucoma (decrease IOP) 5. Hyperthyroidism (blocks excessive catecholamine action - propanolol used extensively) 6. Neurological (reduce frequency and intensity of migraine) 7. B3 receptor blockade (theoretically, B3 may cause heart failure due to decreased inotropy) |
