Adrenergic blockers

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Adrenergic blockers

  1. 1. Drugs Affecting The Autonomic Nervous System Adrenergic Agents and Adrenergic-Blocking Agents
  2. 2. Adrenergic Agents <ul><li>Drugs that stimulate the sympathetic nervous system (SNS) </li></ul>
  3. 3. Adrenergic Agents <ul><li>Also known as </li></ul><ul><li>adrenergic agonists or sympathomimetics </li></ul>
  4. 4. Adrenergic Agents <ul><li>Mimic the effects of the SNS neurotransmitters: </li></ul><ul><li>norepinephrine (NE) and epinephrine (EPI) </li></ul>
  5. 5. Adrenergic Receptors <ul><li>Located throughout the body </li></ul><ul><li>Are receptors for the sympathetic neurotransmitters </li></ul><ul><li>Alpha-adrenergic receptors: respond to NE </li></ul><ul><li>Beta-adrenergic receptors: respond to EPI </li></ul>
  6. 6. Alpha-Adrenergic Receptors <ul><li>Divided into alpha1 and alpha 2 receptors </li></ul><ul><li>Differentiated by their location on nerves </li></ul>
  7. 7. Alpha 1 -Adrenergic Receptors <ul><li>Located on postsynaptic effector cells (the cell, muscle, or organ that the nerve stimulates) </li></ul>
  8. 8. Alpha 2 -Adrenergic Receptors <ul><li>Located on presynaptic nerve terminals (the nerve that stimulates the effector cells) </li></ul><ul><li>Control the release of neurotransmitters </li></ul>
  9. 9. The predominant alpha-adrenergic agonist responses are: <ul><li>Vasoconstriction and CNS stimulation </li></ul>
  10. 10. Beta-Adrenergic Receptors <ul><li>All are located on postsynaptic effector cells </li></ul><ul><li>Beta 1 -adrenergic receptors—located primarily in the heart </li></ul><ul><li>Beta 2 -adrenergic receptors—located in smooth muscle of the bronchioles, arterioles, and visceral organs </li></ul>
  11. 11. The beta-adrenergic agonist response results in: <ul><li>Bronchial, GI, and uterine smooth muscle relaxation </li></ul><ul><li>Glycogenolysis </li></ul><ul><li>Cardiac stimulation </li></ul>
  12. 12. Dopaminergic Receptors <ul><li>An additional adrenergic receptor </li></ul><ul><li>Stimulated by dopamine </li></ul><ul><li>Causes dilation of the following blood vessels, resulting in INCREASED blood flow </li></ul><ul><ul><li>Renal </li></ul></ul><ul><ul><li>Mesenteric </li></ul></ul><ul><ul><li>Coronary </li></ul></ul><ul><ul><li>Cerebral </li></ul></ul>
  13. 13. Adrenergic Receptor Responses to Stimulation <ul><li>LOCATION RECEPTOR RESPONSE Cardiovascular </li></ul><ul><li>Blood vessels alpha 1 and beta 2 Constriction / dilation </li></ul><ul><li>Cardiac muscle beta 1 Increased contractility </li></ul><ul><li>AV Node beta 1 Increased heart rate </li></ul><ul><li>SA Node beta 1 Increased heart rate </li></ul>
  14. 14. Adrenergic Receptor Responses to Stimulation <ul><li>LOCATION RECEPTOR RESPONSE Gastrointestinal </li></ul><ul><li>Muscle beta 2 Decreased motility </li></ul><ul><li>Sphincters alpha 1 Constriction </li></ul>
  15. 15. Adrenergic Receptor Responses to Stimulation <ul><li>LOCATION RECEPTOR RESPONSE Genitourinary </li></ul><ul><li>Bladder alpha 1 Constriction sphincter </li></ul><ul><li>Penis alpha 1 Ejaculation </li></ul><ul><li>Uterus alpha 1 and beta 2 Contraction/ relaxation </li></ul>
  16. 16. Adrenergic Receptor Responses to Stimulation <ul><li>LOCATION RECEPTOR RESPONSE Respiratory </li></ul><ul><li>Bronchial beta 2 Dilation/relaxation muscles </li></ul>
  17. 17. Catecholamines <ul><li>Substances that can produce a sympathomimetic response </li></ul><ul><li>Endogenous: </li></ul><ul><li>epinephrine, norepinephrine,dopamine </li></ul><ul><li>Synthetic: </li></ul><ul><li>isoproterenol, dobutamine, phenylephrine </li></ul>
  18. 18. Adrenergic Agents Mechanism of Action <ul><li>Direct-acting sympathomimetic: </li></ul><ul><li>Binds directly to the receptor and causes a physiologic response </li></ul>
  19. 19. Adrenergic Agents Mechanism of Action <ul><li>Indirect-acting sympathomimetic: </li></ul><ul><li>Causes the release of catecholamine from the storage sites (vesicles) in the nerve endings </li></ul><ul><li>The catecholamine then binds to the receptors and causes a physiologic response </li></ul>
  20. 20. Adrenergic Agents Mechanism of Action <ul><li>Mixed-acting sympathomimetic: </li></ul><ul><li>Directly stimulates the receptor by binding to it </li></ul><ul><li>AND </li></ul><ul><li>Indirectly stimulates the receptor by causing the release of stored neurotransmitters from the vesicles in the nerve endings </li></ul>
  21. 21. Drug Effects of Adrenergic Agents <ul><li>Stimulation of alpha-adrenergic receptors on smooth muscles results in: </li></ul><ul><li>Vasoconstriction of blood vessels </li></ul><ul><li>Relaxation of GI smooth muscles </li></ul><ul><li>Contraction of the uterus and bladder </li></ul><ul><li>Male ejaculation </li></ul><ul><li>Decreased insulin release </li></ul><ul><li>Contraction of the ciliary muscles of the eye (dilated pupils) </li></ul>
  22. 22. Drug Effects of Adrenergic Agents <ul><li>Stimulation of beta 2 -adrenergic receptors on the airways results in: </li></ul><ul><li>Bronchodilation (relaxation of the bronchi) </li></ul><ul><li>Uterine relaxation </li></ul><ul><li>Glycogenolysis in the liver </li></ul>
  23. 23. Drug Effects of Adrenergic Agents <ul><li>Stimulation of beta1-adrenergic receptors on the myocardium, AV node, and SA node results in CARDIAC STIMULATION: </li></ul><ul><li>Increased force of contraction (positive inotropic effect) </li></ul><ul><li>Increased heart rate (positive chronotropic effect) </li></ul><ul><li>Increased conduction through the AV node (positive dromotropic effect) </li></ul>
  24. 24. Adrenergic Agents: Therapeutic Uses <ul><li>Anorexiants: adjuncts to diet in the short-term management of obesity </li></ul><ul><li>Examples: benzphetamine phentermine dextroamphetamine Dexedrine </li></ul>
  25. 25. Adrenergic Agents: Therapeutic Uses <ul><li>Bronchodilators: treatment of asthma and bronchitis </li></ul><ul><li>Agents that stimulate beta 2 -adrenergic receptors of bronchial smooth muscles causing relaxation </li></ul><ul><li>Examples: </li></ul><ul><li>albuterol ephedrine epinephrine isoetharine isoproterenol levalbuterol metaproterenol salmeterol terbutaline </li></ul><ul><li>These agents may also affect uterine and vascular smooth muscles. </li></ul>
  26. 26. Adrenergic Agents: Therapeutic Uses <ul><li>Reduction of intraocular pressure and mydriasis (pupil dilation): treatment of open-angle glaucoma </li></ul><ul><li>Examples: epinephrine and dipivefrin </li></ul>
  27. 27. Adrenergic Agents: Therapeutic Uses <ul><li>Nasal decongestant: </li></ul><ul><li>Intranasal (topical) application causes constriction of dilated arterioles and reduction of nasal blood flow, thus decreasing congestion. </li></ul><ul><li>Examples: epinephrine ephedrine naphazoline phenylephrine tetrahydrozoline </li></ul>
  28. 28. Adrenergic Agents: Therapeutic Uses <ul><li>Ophthalmic </li></ul><ul><li>Topical application to the eye surface affects the vasculature of the eye, stimulating alpha receptors on small arterioles, thus relieving conjunctival congestion. </li></ul><ul><li>Examples: epinephrine naphazoline phenylephrine tetrahydrozoline </li></ul>
  29. 29. Adrenergic Agents: Therapeutic Uses <ul><li>Vasoactive sympathomimetics (pressors, inotropes), also called cardioselective sympathomimetics </li></ul><ul><li>Used to support the heart during cardiac failure or shock. </li></ul><ul><li>Examples: </li></ul><ul><li>dobutamine dopamine ephedrine epinephrine fenoldopam isoproterenol methoxamine norepinephrine phenylephrine </li></ul>
  30. 30. Adrenergic Agents: Side Effects <ul><li>Alpha-Adrenergic Effects </li></ul><ul><li>CNS: </li></ul><ul><ul><li>headache, restlessness, excitement, insomnia, euphoria </li></ul></ul><ul><li>Cardiovascular: </li></ul><ul><ul><li>palpitations (dysrhythmias), tachycardia, vasoconstriction, hypertension </li></ul></ul><ul><li>Other: </li></ul><ul><ul><li>anorexia, dry mouth, nausea, vomiting, taste changes (rare) </li></ul></ul>
  31. 31. Adrenergic Agents: Side Effects <ul><li>Beta-Adrenergic Effects </li></ul><ul><li>CNS: </li></ul><ul><ul><li>mild tremors, headache, nervousness, dizziness </li></ul></ul><ul><li>Cardiovascular: </li></ul><ul><ul><li>increased heart rate, palpitations (dysrhythmias), fluctuations in BP </li></ul></ul><ul><li>Other: </li></ul><ul><ul><li>sweating, nausea, vomiting, muscle cramps </li></ul></ul>
  32. 32. Adrenergic Agents: Interactions <ul><li>Anesthetic agents </li></ul><ul><li>Tricyclic antidepressants </li></ul><ul><li>MAOIs </li></ul><ul><li>Antihistamines </li></ul><ul><li>Thyroid preparations </li></ul><ul><li>Antihypertensives </li></ul><ul><li>Will directly antagonize another adrenergic agent, resulting in reduced effects </li></ul>
  33. 33. Adrenergic Agents: Nursing Implications <ul><li>Assess for allergies and history of hypertension, cardiac dysrhythmias, or other cardiovascular disease. </li></ul><ul><li>Assess renal, hepatic, and cardiac function before treatment. </li></ul><ul><li>Perform baseline assessment of vital signs, peripheral pulses, skin color, temperature, and capillary refill. Include postural blood pressure and pulse. </li></ul><ul><li>Follow administration guidelines carefully. </li></ul>
  34. 34. Adrenergic Agents: Nursing Implications <ul><li>IV administration: </li></ul><ul><li>Check IV site often for infiltration </li></ul><ul><li>Use clear IV solutions </li></ul><ul><li>Use an infusion device/IV pump </li></ul><ul><li>Infuse agent slowly to avoid dangerous cardiovascular effects </li></ul><ul><li>Monitor cardiac rhythm </li></ul>
  35. 35. Adrenergic Agents: Nursing Implications <ul><li>With chronic lung disease: </li></ul><ul><li>Instruct patients to avoid factors that exacerbate their condition. </li></ul><ul><li>Encourage fluid intake (up to 3000 mL per day) if permitted. </li></ul><ul><li>Educate about proper dosing and equipment care. </li></ul><ul><li>Salmeterol is indicated for PREVENTION of bronchospasms, not management of acute symptoms. </li></ul>
  36. 36. Adrenergic Agents: Nursing Implications <ul><li>Overuse of nasal decongestants may cause rebound nasal congestion or ulcerations. </li></ul><ul><li>Avoid OTC or other medications because of possible interactions. </li></ul><ul><li>Administering two adrenergic agents together may precipitate severe cardiovascular effects such as tachycardia or hypertension. </li></ul><ul><li>Inform patients taking inhaled isoproterenol that their sputum or saliva may turn pink. </li></ul>
  37. 37. Adrenergic Agents: Nursing Implications <ul><li>Monitor for therapeutic effects (cardiovascular uses): </li></ul><ul><li>Decreased edema </li></ul><ul><li>Increased urinary output </li></ul><ul><li>Return to normal vital signs </li></ul><ul><li>Improved skin color and temperature </li></ul><ul><li>Increased LOC </li></ul>
  38. 38. Adrenergic Agents: Nursing Implications <ul><li>Monitor for therapeutic effects (asthma): </li></ul><ul><li>Return to normal respiratory rate </li></ul><ul><li>Improved breath sounds, fewer rales </li></ul><ul><li>Increased air exchange </li></ul><ul><li>Decreased cough </li></ul><ul><li>Less dyspnea </li></ul><ul><li>Improved blood gases </li></ul><ul><li>Increased activity tolerance </li></ul>
  39. 39. Adrenergic-Blocking Agents <ul><li>Bind to adrenergic receptors, but inhibit or block stimulation of the sympathetic nervous system (SNS) </li></ul>
  40. 40. Adrenergic Blocking Agents <ul><li>Have the opposite effect of adrenergic agents </li></ul><ul><li>Also known as </li></ul><ul><ul><li>adrenergic antagonists or sympatholytics </li></ul></ul>
  41. 41. Adrenergic Blocking Agents <ul><li>Sympatholytics inhibit—or LYSE—sympathetic neurotransmitters (norepinephrine and epinephrine) </li></ul>
  42. 42. Adrenergic Blocking Agents <ul><li>Classified by the type of adrenergic receptor they block </li></ul><ul><li>Alpha 1 and alpha 2 receptors </li></ul><ul><li>Beta 1 and beta 2 receptors </li></ul>
  43. 43. Adrenergic-Blocking Agents: Drug Effects and Therapeutic Uses <ul><li>Ergot Alkaloids (Alpha-Blockers) </li></ul><ul><li>Constrict dilated arteries going to the brain (carotid arteries) </li></ul><ul><li>Used to treat vascular headaches (migraines) </li></ul><ul><li>Stimulate uterine contractions by inducing vasoconstriction </li></ul><ul><li>Used to control postpartum bleeding </li></ul>
  44. 44. Adrenergic-Blocking Agents: Drug Effects and Therapeutic Uses <ul><li>Alpha-Blockers </li></ul><ul><li>Cause both arterial and venous dilation, reducing peripheral vascular resistance and BP </li></ul><ul><li>Used to treat hypertension </li></ul><ul><li>Effect on receptors on prostate gland and bladder decreased resistance to urinary outflow, thus reducing urinary obstruction and relieving effects of BPH </li></ul>
  45. 45. Adrenergic-Blocking Agents: Drug Effects and Therapeutic Uses <ul><li>Alpha-Blockers </li></ul><ul><li>Phentolamine </li></ul><ul><ul><li>Quickly reverses the potent vasoconstrictive effects of extravasated vasopressors such as norepinephrine or epinephrine. </li></ul></ul><ul><ul><li>Restores blood flow and prevents tissue necrosis. </li></ul></ul>
  46. 46. Adrenergic-Blocking Agents: Side Effects <ul><li>Alpha Blockers </li></ul><ul><li>Body System Side/Adverse Effects </li></ul><ul><li>Cardiovascular Palpitations, orthostatic hypotension, tachycardia, edema, dysrhythmias, chest pain </li></ul><ul><li>CNS Dizziness, headache, drowsiness, anxiety, depression, vertigo, weakness, numbness, fatigue </li></ul>
  47. 47. Adrenergic-Blocking Agents: Side Effects <ul><li>Alpha Blockers </li></ul><ul><li>Body System Side/Adverse Effects </li></ul><ul><li>Gastrointestinal Nausea, vomiting, diarrhea, constipation, abdominal pain </li></ul><ul><li>Other Incontinence, nose bleeding, tinnitus, dry mouth, pharyngitis, rhinitis </li></ul>
  48. 48. Beta Blockers <ul><li>Block stimulation of beta receptors in the SNS </li></ul><ul><li>Compete with norepinephrine and epinephrine </li></ul><ul><li>Selective and nonselective beta blockers </li></ul>
  49. 49. Beta Receptors <ul><li>Beta 1 Receptors </li></ul><ul><li>Located primarily on the heart </li></ul><ul><li>Beta blockers selective for these receptors are called cardioselective beta blockers </li></ul>
  50. 50. Beta Receptors <ul><li>Beta 2 Receptors </li></ul><ul><li>Located primarily on smooth muscles of bronchioles and blood vessels </li></ul>
  51. 51. Nonspecific Beta Blockers <ul><li>Beta blockers that block both beta 1 and beta 2 receptors </li></ul>
  52. 52. Beta Blockers: Mechanism of Action <ul><li>Cardioselective (Beta1) </li></ul><ul><li>Decreases heart rate </li></ul><ul><li>Prolongs SA node recovery </li></ul><ul><li>Slows conduction rate through the AV node </li></ul><ul><li>Decreases myocardial contractility, thus decreasing myocardial oxygen demand </li></ul>
  53. 53. Beta Blockers: Mechanism of Action <ul><li>Nonspecific (Beta 1 and Beta 2 ) </li></ul><ul><li>Effects on heart: Same as cardioselective </li></ul><ul><li>Bronchioles: Constriction, resulting in narrowing of airways and shortness of breath </li></ul><ul><li>Blood vessels: Vasoconstriction </li></ul>
  54. 54. Beta Blockers: Therapeutic Uses <ul><li>Anti-angina: decreases demand for myocardial oxygen </li></ul><ul><li>Cardioprotective: inhibits stimulation by circulating catecholamines </li></ul><ul><li>Class II antidysrhythmic </li></ul>
  55. 55. Beta Blockers: Therapeutic Uses <ul><li>Antihypertensive </li></ul><ul><li>Treatment of migraine headaches </li></ul><ul><li>Glaucoma (topical use) </li></ul>
  56. 56. Beta Blockers: Side Effects <ul><li>Body System Side/Adverse Effects </li></ul><ul><li>Blood Agranulocytosis, thrombocytopenia </li></ul><ul><li>Cardiovascular AV block, bradycardia, congestive heart failure, peripheral vascular insufficiency </li></ul><ul><li>CNS Dizziness, mental depression, lethargy, hallucinations </li></ul>
  57. 57. Adrenergic-Blocking Agents: Side Effects <ul><li>Beta Blockers </li></ul><ul><li>Body System Side/Adverse Effects </li></ul><ul><li>Gastrointestinal Nausea, dry mouth, vomiting, diarrhea, cramps, ischemic colitis </li></ul><ul><li>Other Impotence, rash, alopecia, bronchospasms </li></ul>
  58. 58. Adrenergic Blocking Agents: Nursing Implications <ul><li>Assess for allergies and history of COPD, hypotension, cardiac dysrhythmias, bradycardia, CHF, or other cardiovascular problems </li></ul><ul><ul><li>Any preexisting condition that might be exacerbated by the use of these agents might be a CONTRAINDICATION to their use. </li></ul></ul>
  59. 59. Adrenergic Blocking Agents: Nursing Implications <ul><li>Remember that alpha blockers may precipitate hypotension. </li></ul><ul><li>Remember that beta blockers may precipitate bradycardia, hypotension, heart block, CHF, and bronchoconstriction. </li></ul>
  60. 60. Adrenergic Blocking Agents: Nursing Implications <ul><li>Avoid OTC medications because of possible interactions. </li></ul><ul><li>Possible drug interactions may occur with: </li></ul><ul><ul><li>Antacids (aluminum hydroxide type) </li></ul></ul><ul><ul><li>Antimuscarinics/anticholinergics </li></ul></ul><ul><ul><li>Diuretics and cardiovascular drugs </li></ul></ul><ul><ul><li>Neuromuscular blocking agents </li></ul></ul><ul><ul><li>Oral hypoglycemic agents </li></ul></ul>
  61. 61. Adrenergic Blocking Agents: Nursing Implications <ul><li>Encourage patients to take medications as prescribed. </li></ul><ul><li>These medications should never be stopped abruptly. </li></ul><ul><li>Report constipation or the development of any urinary hesitancy or bladder distention. </li></ul>
  62. 62. Adrenergic Blocking Agents: Nursing Implications <ul><li>Teach patients to change positions slowly to prevent or minimize postural hypotension. </li></ul><ul><li>Avoid caffeine (excessive irritability). </li></ul><ul><li>Avoid alcohol ingestion and hazardous activities until blood levels become stable. </li></ul><ul><li>Patients should notify their physician if palpitations, dyspnea, nausea, or vomiting occur. </li></ul>
  63. 63. Beta Blocking Agents: Nursing Implications <ul><li>Rebound hypertension or chest pain may occur if this medication is discontinued abruptly. </li></ul><ul><li>Patients should notify their physician if they become ill and unable to take medication. </li></ul><ul><li>Inform patients that they may notice a decrease in their tolerance for exercise; dizziness and fainting may occur with increased activity. Notify the physician if these problems occur. </li></ul>
  64. 64. Beta Blocking Agents: Nursing Implications <ul><li>Patients should report the following to their physician: </li></ul><ul><li>Weight gain of more than 2 pounds (1 kg) within a week </li></ul><ul><li>Edema of the feet or ankles </li></ul><ul><li>Shortness of breath </li></ul><ul><li>Excessive fatigue or weakness </li></ul><ul><li>Syncope or dizziness </li></ul>
  65. 65. Adrenergic Blocking Agents: Nursing Implications <ul><li>Monitor for side effects, including: </li></ul><ul><li>Hypotension Fatigue </li></ul><ul><li>Tachycardia (alpha blockers) Lethargy </li></ul><ul><li>Bradycardia Depression </li></ul><ul><li>Heart block Insomnia </li></ul><ul><li>CHF Vivid nightmares </li></ul><ul><li>Increased airway resistance </li></ul>
  66. 66. Adrenergic Blocking Agents: Nursing Implications <ul><li>Monitor for therapeutic effects </li></ul><ul><li>Decreased chest pain in patients with angina </li></ul><ul><li>Return to normal BP and P </li></ul><ul><li>Other specific effects, depending on the use </li></ul>
  67. 67. Alpha-Adrenergic Blockers <ul><li>Type of blockade Phenoxybenzamine – non-competitive; slow onset and long duration. 2-stage blockade. All the rest: competitive </li></ul><ul><li>Selectivity Nonselective: Phenoxybenzamine and phentolamine alpha-1 selective: Prazosin, terazosin, others alpha-2 selective: Yohimbine alpha/beta blockers: Labetalol </li></ul><ul><li>Others: phenothiazines, tricyclic antidepressants </li></ul>www.freelivedoctor.com
  68. 68. Phenoxybenzamine Prazosin Yohimbine www.freelivedoctor.com
  69. 69. EPI EPI + Phenoxybenzamine Phenoxybenzamine alone Receptors no longer available [Agonist], mg/kg % Maximal Increase Decrease in the maximal efficacy of Epi due to a decrease in the number of receptors www.freelivedoctor.com
  70. 70. Pharmacological Effects -Phenoxybenxamine <ul><li>Cardiovascular system Blood pressure Cardiac Effects Organ Blood Flow Capillaries </li></ul><ul><li>Central nervous system </li></ul><ul><li>Respiratory system </li></ul>www.freelivedoctor.com
  71. 71. Pharmacological Effects – cont’d <ul><li>Eye - miosis </li></ul><ul><li>GI tract – Increased motility </li></ul><ul><li>Urinary bladder – decreased tone in sphincter </li></ul><ul><li>Metabolic effects – increased insulin secretion </li></ul>www.freelivedoctor.com
  72. 72. Adverse effects <ul><li>Postural hypotension </li></ul><ul><li>Tachycardia </li></ul><ul><li>Sedation </li></ul><ul><li>Nasal stuffiness </li></ul><ul><li>Miosis </li></ul><ul><li>Impotence (inhibits ejaculation) </li></ul><ul><li>Exercise care in hypovolemic patients </li></ul>www.freelivedoctor.com
  73. 73. Imidazoline derivatives - phentolamine <ul><li>Many other effects including: </li></ul><ul><li>Parasympathomimetic </li></ul><ul><li>Increased gastric acid secretion </li></ul><ul><li>Cardiac stimulation </li></ul><ul><li>Increased secretion from exocrine glands, such as salivary, sweat, lacrimal, pancreatic </li></ul><ul><li>Coronary artery disease and peptic ulcer relative contraindication to it. </li></ul>www.freelivedoctor.com
  74. 74. Alpha-1 selective blockers Prazosin <ul><li>Less cardiac stimulation since it preserves alpha-2 mediated negative feedback + other mechanisms </li></ul><ul><li>Used in congestive heart failure and in hypertension but tolerance develops with time, maybe due to fluid retention. </li></ul><ul><li>Adverse effects: First dose phenomenon. </li></ul><ul><li>Favorable effect on plasma lipids: increase HDL/LDL ratio </li></ul>www.freelivedoctor.com
  75. 75. ADR (µg/Kg) 1 10 100 500 0.1 1 10 100 500 +PRAZOSIN BP HR Effect of Adrenaline (ADR) on Blood Pressure and Heart Rate Before and After Prazosin www.freelivedoctor.com
  76. 76. Alpha-2 selective blockers Yohimbine <ul><li>Cardiovascular effects – peripheral and central effects </li></ul><ul><li>Blocks other receptors also – serotonin, dopamine </li></ul><ul><li>Increases ADH release </li></ul><ul><li>Enhances sexual activity – aphrodisiac </li></ul><ul><li>Potential uses: depression, obesity, NIDDM </li></ul>www.freelivedoctor.com
  77. 77. Ergot alkaloids <ul><li>Interact with serotonin and dopamine receptors also </li></ul><ul><li>Direct smooth muscle contraction </li></ul><ul><li>Structure-activity relationships </li></ul><ul><li>Coronary vasoconstriction </li></ul><ul><li>Toxicity: GI, vascular insufficiency –ergotism </li></ul><ul><li>Use in migraine and post-partum </li></ul>www.freelivedoctor.com
  78. 78. Therapeutic Uses of Alpha-Adrenergic Blockers <ul><li>Hypertension - alpha-1 selective </li></ul><ul><li>Conditions associated with increased sympathetic activity – e.g. pheochromocytoma </li></ul><ul><li>Hemodynamic shock </li></ul><ul><li>Peripheral vascular disease – Raynaud’s </li></ul><ul><li>Congestive heart failure </li></ul><ul><li>Benign prostatic hyperplasia </li></ul><ul><li>Pulmonary hypertension – tolazoline </li></ul><ul><li>Yohimbine or intracavernous phentolamine+papaverine for impotence </li></ul>www.freelivedoctor.com

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