Anesthesia Pharmacology Chapter 6:  Autonomic Adrenergic Pharmacology

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Receptor Classification

 

Clonidine (Catapres)

  • Clonidine acts in the brain at post-synaptic alpha2 receptors, inhibiting adrenergic outflow from the brainstem. Inhibition of sympathetic outflow results in a decrease in blood pressure.

  • Clonidine reduces cardiac output (by reducing both stroke volume and heart rate) and peripheral resistance. Reduction in stoke volume occurs due to increased venous pooling (decreased preload).

  • Clonidine does not interfere with cardiovascular responses to exercise.

  • Renal blood flow and function is maintained during clonidine treatment.

  • Clonidine has minimal or no effect on plasma lipids.

 

 

Catecholamine Refractoriness

 Receptors

 G proteins

 Adenyl cyclase

 Cyclic nucleotide phosphodiesterase

Lefkowitz, R.J, Hoffman, B.B and Taylor, P. Neurotransmission: The Autonomic and Somatic Motor Nervous Systems, In, Goodman and Gillman's The Pharmacologial Basis of Therapeutics,(Hardman, J.G, Limbird, L.E, Molinoff, P.B., Ruddon, R.W, and Gilman, A.G.,eds) TheMcGraw-Hill Companies, Inc.,1996, pp.112-137.

 

Metabolic Transformation

Two primary degradative enzymes:

Monoamine Oxidase (MAO)

Catechol-O-Methyl Transferase (COMT)

Pulmonary Uptake

 

 

Clinical Use: Sympathomimetic Agents: Brief Summary 

 

Alpha Adrenergic Agonists

 

"Catecholamine-secreting pheochromocytoma of adrenal medulla gross. Note spherical enlargement of the adrenal medulla in this cross section of adrenal."-  1999 KUMC Pathology and the University of Kansas, used with permission; courtesy of Dr. James Fishback, Department of Pathology, University of Kansas Medical Center. For more information concerning endocrine pathology

 

Non-selective Adrenergic agonists

ß1-adrenergic receptor selective agonists

ß2-selective agonists (various drugs)

 

Overview-- Varied Clinical Uses of Adrenergic Drugs

 Drugs Used in Treating Shock

Dopamine and Dobutamine

Dobutamine

Dopamine (Intropin)

Therapeutic Uses for Dopamine & Dobutamine: Summary

 

 

 

 

Drugs in Cardiogenic Shock: Nitrates, Adrenergic Agonists, Amrinone (Inocor) and Milrinone (Primacor)

 

Cardiogenic Shock may be caused myocardial stunning due to prolonged cardiopulmonary bypass

Overview: Amrinone and milrinone

 

 

 

  Antihypertensive Effects of some adrenergic receptor agonists

Adrenergic Agonists in Treating some Cardiac Arrhythmias

Vascular Effects: alpha Adrenergic Agonists

Congestive Heart Failure

Asthma  

Nasal Decongestion

Allergic Reactions

 

Hollenberg, S.M. and Parrillo, J.E., Shock, In Harrison's Principles of Internal Medicine 14th edition, (Isselbacher, K.J., Braunwald, E., Wilson, J.D., Martin, J.B., Fauci, A.S. and Kasper, D.L., eds) McGraw-Hill, Inc (Health Professions Division), 1998, p. 215-222

Hoffman, B.B and Lefkowitz, R.J, Catecholamines, Sympathomimetic Drugs, and Adrenergic Receptor Antagonists, In, Goodman and Gillman's The Pharmacologial Basis of Therapeutics, (Hardman, J.G, Limbird, L.E, Molinoff, P.B., Ruddon, R.W, and Gilman, A.G.,eds) TheMcGraw-Hill Companies, Inc.,1996, pp.222-224.

Stoelting, R.K., "Sympathomimetics", in Pharmacology and Physiology in Anesthetic Practice, Lippincott-Raven Publishers, 1999, p.259.

 

 

Therapeutic uses of indirect-acting adrenoceptor agonists

 

Ephedrine

 

Mephentermine (Wyamine)

 

Metaraminol (Aramine)

Stoelting, R.K., "Sympathomimetics", in Pharmacology and Physiology in Anesthetic Practice, Lippincott-Raven Publishers, 1999, pp. 271-272

 

 

 

Adverse Effects: beta-Adrenoceptor Antagonists

 

alpha-Adrenergic Antagonists (Blockers)

  Introduction

 

alpha1-adrenergic receptor antagonists- Cardiovascular Effects

 

alpha2-adrenergic receptor antagonists

 

 

Phenoxybenzamine (Dibenzyline)

 Therapeutic Uses for alpha-adrenergic blocking drugs

 

 

Phentolamine  (Regitine) and Tolazoline (Priscoline)

Prazosin (Minipress) and Terazosin (Hytrin)

 

 

Other alpha adrenergic receptor blockers

Hoffman, B.B and Lefkowitz, R.J, Catecholamines, Sympathomimetic Drugs, and Adrenergic Receptor Antagonists, In, Goodman and Gillman's The Pharmacologial Basis of Therapeutics, (Hardman, J.G, Limbird, L.E, Molinoff, P.B., Ruddon, R.W, and Gilman, A.G.,eds) TheMcGraw-Hill Companies, Inc.,1996, pp.225-232.

 

 

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ß-Adrenergic Antagonists

Introduction

 

 

Nonselective-ß adrenergic receptor antagonists

 

 

Selective-ß1 adrenergic receptor antagonists

 

Adverse Effects of ß adrenergic receptor antagonists

 

  Therapeutic Uses for beta adrenergic receptor antagonists (Blockers)

Hoffman, B.B and Lefkowitz, R.J, Catecholamines, Sympathomimetic Drugs, and Adrenergic Receptor Antagonists, In, Goodman and Gillman's The Pharmacologial Basis of Therapeutics, (Hardman, J.G, Limbird, L.E, Molinoff, P.B., Ruddon, R.W, and Gilman, A.G.,eds) The McGraw-Hill Companies, Inc.,1996, pp.232-242.

Stoelting, R.K., "Sympathomimetics", in Pharmacology and Physiology in Anesthetic Practice, Lippincott-Raven Publishers, 1999, pp. 293-301

 

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