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21 Cards in this Set
- Front
- Back
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True/False: Alpha1 Adrenergic Antagonists are no longer first line agents.
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True
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What are the mechanisms of action of Alpha1 Antagonists?
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1. reversible blockade of vascular Alpha1 receptors
2. Reduction of TPR 3. Dilation of precapillary arterioles 4. Reflex increase in HR |
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What is Prazosin? What does it do?
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Prazosin is a selective Alpha1 antagonist. It has evidence of mild reduction in LDL and TGs and increased HDL. It is used in combination with Beta-Blockers and Diuretics.
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What is a drawback of Prazosin?
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It's dosing is 2-3/daily.
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What are six side effects of Prazosin?
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1. Orthostatic hypotension
2. Postural dizziness (Headache, Drowsiness, and lack of energy) 3. Mild reflex tachycardia 4. Increased renin release 5. Increased sodium and water retention 6. Impotence |
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What are three possible reasons that Prazosin only has mild reflex tachycardia?
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1. May have central sympatholytic activity
2. Vasodilate both arteries and veins 3. Alpha1 mediated chronotropic effects |
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What are two drug interactions with Prazosin?
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1. NSAIDS attentuate response
2. BB may enhance postural hypotension |
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What types of patients would you take caution in prescribing Prazosin to?
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Cardiac and renal failure
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What are two other Alpha1 selective agents related to Prazosin?
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1. Terazosin
2. Doxazosin |
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Name four properties of the other Alpha1 selective agents Terazosin and Doxazosin.
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1. Antihypertensive
2. Will treat Benign Prosthetic Hyperplasia 3. Longer half life, so only once daily dosing 4. Decreases insulin resistance |
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What is ALLHAT? The trial of which medication was stopped? Why?
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ALLHAT - Antihypertensive Lipid Lowering Heart Attack Trial
Doxazosin arm of trial stopped because of increased incidence of CHF |
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What are two Alpha1 blocking agents that are not approved in US but are available in Europe? Why haven't they been approved here?
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1. Ketanserin - 5HT2a, 5HT2c, and Alpha1 antagonist
2. Urapadil - Alpha1 antagonist and Alpha2 and 5HT1a agonist Not yet approved because of serotonin effects. |
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Name an Alpha1a selective antagonist. What are its actions? Side effects?
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Tamsulosin.
BPH and has limited effects on vasculature (Alpha1b receptors on vasculature) Side effects: hypotension and dizziness |
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Name two mixed antagonists.
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1. Labetalol - Beta-Blocker with ISA at Beta2 receptors and Alpha1 anatgonist
2. Carvedilol - Beta-Blocker, Alpha1 antagonist, No ISA or membrane stabilizing activity |
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How is vascular smooth muscle maintained?
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VSM has a difference in membrane potential. This difference is maintained by Na/K ATPase. Cells always have negative charge on inside compared to outside. Na will always rush in and K will always move outward. Cl usually goes in and Ca is higher concentrated on the outside than the inside. The amount of free calcium is small.
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What are the Na, K, Cl, and free Ca concentrations on the outside versus the inside of VSM?
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Outside:
Na - 140 mM K - 4 mM Cl - 6 mM free Ca - about 1.2 mM Inside: Na - 10-16 mM K - 120 mM Cl - 6 mM free Ca - about 100 nM |
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How does skeletal muscle contract?
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Skeletal muscle has potential difference of approximately 90mV. You have a resting membrane potential and then you get nerve impulse down surface of skeletal muscle which opens Na channels which depolarizes cell. T-type and L-type voltage sensitive channels open and close by changes in membrane potential. The T-type (transient) will open first (at -50 and closes at -30) and allows Ca to move from outside to inside and starts changing the membrane potential until get to -20mV and L-type channels get even more Ca rushing in.Ca acts on troponin and tropomycin to expose active side of actin and myosin and allow them to interact to cause muscle contraction.
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How do you cause relaxation of VSM?
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Just like with skeletal muscle, you have to get rid of the Ca.
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What does tropomycin do?
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Keeps actin and myosin from interacting. Troponin C Ca binding protein that when Ca bound changes Tropomyosin to allow interaction to occur.
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True/False: Sarcoplasmic Reticulum is not well-developed in smooth muscle.
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True
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What acts on myosin to relax? What stimulates this action?
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Phosphotase acts on myosin to relax. cGMP and cAMP stimulate phosphotases to relax.
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