Adrenergic Drugs

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Adrenergic Drugs
2010-11-07 19:25:05
Adrenergic Drugs

Adrenergic Drugs
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  1. This class of drugs mimic sympathetic function. They do so either by directly stimulating the adrenergic receptors or by allowing more epinephrine to be present in the synaptic cleft. Indirect acting agents of this class either cause release of neurotransmitter or prevent the normal termination of action (reuptake).
  2. What are the subclasses within sypathomimetics? (4)
    • Catecholamines
    • Non-Catecholamines: Alpha Agonists, Beta Agonists, Inhibitors of Reuptake
  3. Are catecholamines effective by the oral route?
    No, none are
  4. What are the subclasses of Catecholamines? (3)
    • Epinephrine
    • Norepinephrine
    • Isoproterenol
  5. Endogenous sympathetic substances within the class of Sympathomimetics
  6. A catecholamine that acts on all alpha- and beta-adrenoreceptors in the body. The primary catecholamine liberated from the adrenal medulla. Not effective when given orally. Short duration of action. Given parenterally or by inhalation. The combined use of an alpha- and a beta-adrenoreceptor blockade would eliminate all response to this.
  7. What type of receptors does epinephrine act on?
    Alpha- and beta-adrenoreceptors
  8. Is epinephrine short or long duration?
  9. What is the effect of epinephrine on the heart?
    Stimulates the Beta1 -adrenoreceptors to increase heart rate and contractility
  10. What drug acts on beta2-adrenoreceptors to relax bronchial smooth muscle in the treatment of asthma and for treating bronchospasm during anaphylactic shock?
  11. Which catecholamine is the neurotransmitter released from sympathetic nerve endings acting on all alpha-adrenoreceptors as well as the beta1-adrenoreceptors? Not clinically useful. Not orally effective. Very short acting even when administered parenterally. A bolus injection will increase blood pressure due to both vasoconstriction and increased cardiac output.
  12. What receptors do norepinephrine act on?
    Alpha- and beta1-adrenoreceptors
  13. What will a bolus injection of NE do?
    Increase blood pressure due to both vasoconstriction and increased cardiac output
  14. Which catecholamine is a synthetic compound and is an almost pure beta-adrenergic stimulant? Acts potently on all beta-adrenoreceptors. Route of administration is injection or inhalation. Main use is to relieve bronchoconstrictive states with the cardiovascular effects usually being untoward side effects.
    Isoproterenol (ISO)
  15. Which receptor types do Isoproterenol work on?
    All beta-adrenoreceptors
  16. What is the main use of Isoproterenol?
    To relieve bronchoconstrictive states
  17. Which drugs are classified as non-catecholamine, alpha agonist Sympathomimetics? (5)
    • Amphetamine
    • Ephedrine
    • Methamphetamine
    • Phenylephrine
    • Tyramine
  18. That non-catecholamic alpha agonist is a potent indirect acting sympathomimetic which causes a massive release of NE from sympathetic nerve endings. Found in high concentrations in certain foods. Readily inactivated by mitochondrial MAO in the gut and the liver. May precipitate a hypertensive crisis in patients taking a MAO inhibitor to treat depression. Useful experimental tool to establish the integrity of sympathetic neurons
  19. Indirect acting sympathomimetics that are orally effective and readily enter the CNS. Dangerous drugs. Limited therapeutic justification. Produce a temporary elevation of mood and appetite suppression. Rebound depression typically develops. Highly toxic. Can be lethal. Chronic toxicity can mimic schizophrenia (reversible upon withdrawal). Only two valid medical uses: Hyperkinetic childen and narcoleptics
    • Amphetamine
    • Methamphetamine
  20. What are the two medical uses for amphetamines?
    • Hyperkinetic children who respond by becoming more sedate and thus increase their attention span
    • Nacoleptics
  21. An alpha agonist, non-catecholamine sympathomimetic that acts an an agonist on all alpha- and beta-receptors in the body. Releases NE from neuronal stores. Can be used as an oral treatment for bronchial asthma, as well as for ear and nasal congestion. Can be used as a pressor agent and in opthamology to produce short lasting mydriasis without cycloplegia
  22. What receptors do Ephedrine work on?
    All alpha- and beta-adrenoreceptors in the body
  23. What are the clinical uses of Ephedrine?
    • Bronchial Asthma
    • Ear and nasal congestion
    • Pressor agent
    • Short acting mydriasis without cycloplegia
  24. A direct acting sympathomimetic with primarily alpha-adrenergic stimulating effects. Orally effective only when given in extremely large doses. Used as a pressor agent and in opthamology to produce mydriasis. Used as a nasal spray, but frequently cause a rebound congestion that is worse than the initial congestion
  25. What receptors does Phenylephrine work on?
    Primarily alpha-adrenergic receptors
  26. What drug is known as a non-catecholamine, beta agonist Sympathomimetic?
  27. A drug for the treatment of asthma. Long acting. Fewer cardiac effects than tertubaline. A beta agonist
  28. What is albuterol used for? Is it short or long acting?
    • Asthma
    • Long Acting
  29. A local anesthetic drug that is also a potent inhibitor of NE reuptake I.
  30. What are the subclasses of the Blockers of Adrenergic Nerve Function? (3)
    • CNS Acting Sympathoinhibitor
    • Catecholamine Depletion
    • Adrenergic Receptor Antagonists
  31. What is the main effect of CNS acting sympatho-inhibitory agents?
    A dramatic reduction in sympathetic neural tone when CNS alpha2-adrenoreceptors are stimulated. This hypotensive action lasts for hours
  32. What drug is a CNS Acting Sympathoinhibitor?
  33. An imidazoline that is a popular anti-hypertensive drug. A potent alpha2-adrenoreceptor stimulant that readily penetrates into the CNS. Acts to decrease sympathetic tone to the blood vessels and heart. Enhances vagal outflow to the heart by potentiating baroreceptor mechanisms. Also used for opioid and ethanol withdrawal.
  34. What are the main clinical conditions Clonidine is used to treat?
    • Hypertension
    • Opioid and Ethanol Withdrawal
  35. What is the main effects of Catecholamine Depletion agents?
    Reduce sympathetic reactivity
  36. What drug is a catecholamine depleter?
  37. This drug acts to interrupt the vesicular storage mechanism in sympathetic nerves. It has an antihypertensive effect. Only very large doses cause a sympathomimetic action due to the leakage of NE from the nerve ending. Readily enters CNS and depletes all monoaminergic NTs (NE, EPI, DA, S). Has many side effects that limit its usefulness as an antihypertensive drug (sedation and Parkinson's like syndrome)
  38. What is the main use of Reserpine?
    Anti-hypertensive agent, but many side effects (sedation and Parkinsonian symptoms)
  39. How would alpha-adrenoreceptor blockade manifest clinically?
    Reduction of systemic blood pressure.
  40. What are side effects of alpha-adrenoreceptor blockade?
    • Postural hypotension
    • Reflex tachycardia
    • Nasal congestion
    • Failure of ejaculation
  41. What are the Alpha-adrenoreceptor blockers? (4)
    • Phenoxybenzamine
    • Phentolamine
    • Prazosin
    • Yohimbine
  42. How would beta1-adrenergic blockade manifest clinically?
    Will mainly affect innervation to the heart and sympathetic control of renin release from the JG apparatus of the kidney. Reduction in HR, myocardial contractility, conduction velocity, and renin release.
  43. What is the effect of beta2-adrenergic blockade?
    • Prevent relaxation of bronchial and vascular smooth muscle, and reduce certain metabolic responses.
    • Serious side effects may occur because the effect of EPI on bronchial smooth muscle will be excluded and many of the important metabolic effects of EPI will be prevented
  44. What are the major beta-adrenergic blockers? (3)
    • Atenolol
    • Metoprolol
    • Propranolol
  45. This drug is a classical antagonist that competes with NE for occupation of alpha-adrenoreceptors. Blocks both subtypes of alpha receptors, but prefers alpha1s. Short acting. Used as a screening test for pheochromocytoma.
  46. What type of receptors do Phentolamine affect?
    Block alphas
  47. What is the main use of Phentolamine?
    Screening test for pheochromocytoma
  48. Does phentolamine have a long or short duration of action?
  49. This drug is a potent alpha-adrenoreceptor antagonist. High preference for alpha1-receptors. Very long duration of action. Is initially a competitive antagonist but has the ability to irreversibly bind to the receptor. Therefore, after 30-60 min it reverts from a competitive to a non-competitive mechanism.
  50. What type of receptors do Phenoxybenzamine act on?
    Alpha Antagonists, preferentially alpha1
  51. Does Phenoxybenzamine have a short or long duration of action?
    Very long lasting
  52. This drug is a selective alpha1-adrenoreceptor antagonist that does not produce the large reflex tachycardia seen with other alpha antagonists. Therefore, is useful for treating some hypertensive patients. There is some "first dose" effect, however, so initially less drug should be slowly administered
  53. What type of receptors does Prazosin act on?
    Alpha1-adrenoreceptor antagonist
  54. What can Prazosin be used for?
  55. What is the "first dose" effect seen with Prazosin, and what can be done about it?
    • Some patients respond with an initial hypotensive effect and loss of consciousness
    • Initially less drug should be slowly administered
  56. This drug is a selective alpha2-adrenoreceptor antagonist. Clinical use is limited to experimental studies in pts with spinal cord damage. Prevents the CNS hypotensive effects of clonidine and alpha-methyldopa.
  57. What receptors do Yohimbine work on?
    Alpha2-adrenoreceptor antagonist
  58. What is the clinical use of Yohimbine?
    Limited to experimental studies of pts with spinal cord damage
  59. This drug is non-selective (blocks both beta subtypes). Initially used to treat cardiac arrhythmias. Potent local anesthetic. Effective antihypertensive drug. Well absorbed orally, but has potent first pass effect (only ~30% remains in plasma, and ~90% of that is bound to plasma proteins). Dose is therefore difficult to control. Elimination is primarily hepatic.
  60. Which receptors do Propranolol act on?
    Block all betas
  61. What is Propranolol primarily used to treat?
    • Cardiac arrhythmias
    • Hypertension
  62. This drug is primarily a beta1-adrenoreceptor antagonist. Reduces plasma renin but has less metabolic and bronchial effects. Elimination is primarily hepatic. Side effects include fatigue, dizziness, headache, and insomnia
  63. This drug is primarily a beta1-adrenoreceptor antagonist. Has a longer half-life than Metoproprolol, and produces less CNS side effects. Secreted renally.
  64. Which beta blocker acts on both betas?
  65. WHich beta blocker is secreted renally (other two are hepatic)?
  66. Which Andrenergic receptor antagonists are alpha and beta blockers? (2)
    • Carvedilol
    • Labetalol
  67. Has both alpha and beta blocking abilities. Nonselective beta antagonist and alpha1 selective blocker. Alpha blocking effect predominates. Long duration. Some first pass effects. Decreases plasma renin. Can be administered orally or i.v. Hepatic metabolism. Effective antihypertensive agent. Postural hypotension is prob in some pts
  68. What is a primary use of Labetalol?
    Antihypertensive agent
  69. This drug has similar actions as Labetolol but is also a "free radical scavenger" so may protect the heart cells from damage. Approved for use in treating certain pts with congestive heart failure
  70. What is a primary use of Carvedilol?
    Congestive Heart Failure