Lesson 12: Drugs Acting on Autonomic Nervous System PDF

LESSON 12: DRUGS ACTING ON AUTONOMIC NERVOUS SYSTEM PROF. RUBY D. ESPARES  OBJECTIVES After reading this chapter the students is expected to: 1. Correctly identify the different classes of drugs affecting the autonomic nervous system(autonomic drugs) 2. Discuss the effects and therap...

LESSON 12: DRUGS ACTING ON AUTONOMIC NERVOUS SYSTEM PROF. RUBY D. ESPARES  OBJECTIVES After reading this chapter the students is expected to: 1. Correctly identify the different classes of drugs affecting the autonomic nervous system(autonomic drugs) 2. Discuss the effects and therapeutic uses of various drugs 3. Identify side effects and contraindications of commonly used autonomic drugs.  Drugs Acting on Autonomic Nervous System 3 INTRODUCTION The Nervous System controls all the major functions of the body. Central Nervous System (CNS) – is made up of Brain and Spinal Cord Peripheral Nervous System (PNS) – consists the nerves that connect the Brain and Spinal Cord to the rest of the body; receives stimuli from the CNS and initiates responses to the stimuli after it’s interpreted by the brain The peripheral nervous system includes Somatic – Voluntary (person has control e.g., skeletal muscle) Autonomic Nervous Systems (ANS) - Involuntary (person has little or no control e.g., controls and regulation of the heart, respiratory system, GI Tract, bladder, glands, maintenance of body temperature) The ANS is subdivided into two major sub-divisions; this classification is based on both anatomic and physiologic grounds; Sympathetic (thoracolumbar) Parasympathetic (craniosacral) Presentation title 4 ANS HAS TWO SETS OF NEURONS AFFERENT (Sensory) - sends impulses to the CNS for interpretation EFFERENT – receives impulses (info) from the brain and transmits from the spinal cord to the effector organ cells Presentation title 5 2 BRANCHES OF EFFERENT PARASYMPATHETIC NERVOUS SYSTEM - is concerned primarily with conservation and restoration of function. SYMPATHETIC NERVOUS SYSTEM ( ADRENERGIC ) - In contrast, the sympathetic nervous system is concerned with the expenditure of energy i.e., it has almost opposite functions with parasympathetic nerve stimulation, and it is usually associated with arousal or in emergency situations, i.e., prepares the body for fight-or-flight responses. Presentation title 6 2 IMPORTANT NEUROTRANSMITTERS IN ANS Acetylcholine - is a neurotransmitter which is released after stimulation of the parasympathetic nervous system to act on effector organs (cells) to elicit their response Noradrenaline (Norepinephrine) – is a neurotransmitter of the brain that plays an essential role in the regulation of arousal, attention, cognitive function and stress reactions Presentation title 7 SYMPATHETIC NERVOUS SYSTEM (SNS) ( ADRENERGIC ) NEUROTRANSMITTER – NOREPINEPHRINE or NORADRENALINE ADRENERGIC AGONISTS – Drugs that mimic the functions of the SNS. Ex. Sympathomimetics or adrenergic drugs ADRENERGIC ANTAGONISTS – Drugs that inhibit the action of SNS. Ex. Adrenergic blockers, sympatholytics or adrenolytics Presentation title 8 FOUR TYPES OF RECEPTOR ORGAN CELLS ALPHA 1 – vasoconstriction to increase BP ALPHA 2 – vasodilation to decrease BP BETA 1 – increase heart rate BETA 2 – bronchodilation + relaxation of uterine muscles AUTONOMIC DRUGS Presentation title 10 There are several drugs affecting the autonomic nervous system which, for a better understanding of specific drugs, are classified into groups. 1.DRUGS ACTING ON THE SYMPATHETIC NERVOUS SYSTEM a.SYMPATHOMIMETICS OR ADRENERGIC DRUGS: are drugs that mimic the effects of sympathetic nerve stimulation. b.SYMPATHOLYTICS: are drugs that inhibit the activity of sympathetic nerve or that of sympathomimetics. 2.DRUGS ACTING ON THE PARASYMPATHETIC NERVOUS SYSTEM a.PARASYMPATHOMIMETICS OR CHOLINERGIC DRUGS: are drugs which mimic acetylcholine or the effects of parasympathetic nerve stimulation. b.PARASYMPATHOLYTICS: are drugs that inhibit parasympathetic Presentation title 11 SYMPATHOMIMETIC AGENTS / ADRENERGICS ACTION – Many of the adrenergic drugs stimulates more than one of the adrenergic receptor sites (alpha and beta) RESPONSE – increase BP, pupil dilation, increase HR and bronchodilation USE – Cardiac stimulation, bronchodilator, decongestant S/E – Hyperness in body Presentation title 12 SYMPATHOMIMETIC AGENTS / ADRENERGICS ALBUTEROL – Beta-2 agonist (Bronchodilator) DOPAMINE – alpha-1 and beta-1 stimulation USE – bronchospasm, asthma, bronchitis USE – Hypotension, shock, increase cardiac S/E – nervousness, restlessness output, improve perfusion to vital organs S/E – N&V, H/A C/I – severe cardiac disease, HTN C/I – V. Tach EPINEPHRINE – stimulates alpha and beta USE – allergic reaction, cardiac arrest S/E – nervousness, agitation C/I – cardiac dysrhythmias Presentation title 13 ADRENERGIC BLOCKERS (ANTAGONISTS / SYMPATHOLYTICS Block alpha and beta receptor sites (nonselective) Direct or indirect acting on the release of norepinephrine and epinephrine USE – Cardiac arrythmias (decrease HR), HTN (decrease cardiac output), angina (decrease O2 demand) S/E – Congestive Heart Failure (CHF), bronchospasm, bradycardia, wheezing Presentation title 14 NONSELECTIVE VS. SELECTIVE BETA BLOCKERS Nonselective have an equal inhibitory effect on B1 and B2 receptors Drugs have lots of interactions due to lots of alpha/beta receptor sites throughout body Use with caution on clients with cardiac failure or asthma Selective B1 is helpful in asthma clients Presentation title 15 ADRENERGIC BLOCKING AGENTS INDERAL (PROPRANOLOL) – Nonselective B adrenergic blocker USE – angina, dysrhythmias, HTN, migraines S/E – Many d/t nonselective C/I – asthma, heart block > 1st degree MINIPRESS (Prazosin) – A blocker USE – mild to moderate, HTN S/E – orthostatic hypotension TENORMIN (ATENOLOL), LOPRESSOR (Metoprolol) B1 (cardio) selective USE – mild to moderate HTN, angina CHOLINERGIC AND ANTICHOLINERGIC  Presentation title 17 CHOLINERGIC AGENT (PARASYMPATHOMIMETICS) Cholinergic drugs are also called parasympathomimetics because their effect mimics the effect of parasympathetic nerve stimulation. Administration of these drugs will result in an increase in the parasympathetic activities in the systems innervated by cholinergic nerves. Cholinergic stimulate the parasympathetic nervous system Mimic the neurotransmitter acetylcholine TWO TYPES OF CHOLINERGIC RECEPTORS 1. Muscarinic – stimulates smooth muscle and slows HR 2. Nicotinic – affect skeletal muscle Presentation title CHOLINERGIC AGENT 18 (PARASYMPATHOMIMETICS) There are two groups of cholinergic drugs: 1. Direct-acting: bind to and activate muscarinic or nicotinic receptors (mostly both) and include the following subgroups: a. Esters of choline: Methacholine Carbachol – for glaucoma, retention of urine, paralytic ileus Betanechol - b. Cholinergic alkaloids: Pilocarpine – for glaucoma (pupil constriction) Muscarine Arecoline Nicotine Presentation title 19 CHOLINERGIC AGENT (PARASYMPATHOMIMETICS) 2. Indirect-acting: inhibit the action of acetylcholinesterase enzyme a. Reversible: neostigmine, physostigmine, edrophonium b. Irreversible: Organophosphate compounds; echothiophate BETHANECOL (URECHOLINE) – selective to muscarinic receptors, mimic action of acetylcholine USE – For urinary retention ***NEVER GIVE IM OR IV – Circulatory collapse, hypotension, shock and cardiac arrest PILOCARPINE (POLOCAR) – Ophthalmic – Direct acting  Presentation title 20 CHOLINERGIC BLOCKING AGENTS ANTICHOLINERGICS/PARASYMPATHOLYTICS Drugs that inhibit action of actycholine (ACH) receptors Affects the heart, respiratory tract, GI tract, bladder, eye and exocrine glands Allows the symphathetic nervous system to dominate Anticholinergic and cholinergic drugs have opposite effects Major responses – decreases in GI motility, decrease in salivation, dilation of pupil (mydriasis), increase pulse rate  Presentation title 21 ANTICHOLINERGIC USES – Pre-op meds, bradycardia, G/I/urinary antispasmodic S/E: Dry mouth / dry mucous membrane ATROPINE SULFATE – Inhibits ACH > blocks vagal effects on SA and AV nodes > increase conduction and increase heart rate USE – Bradycardia, peptic ulcer S/E – Most frequent – dry mouth, blurred vision, urine retention, constipation BENTYL (DICYCLOMINE) – Inhibits ACH on muscarinic receptors and decrease GI motility USE – Irritable bowel syndrome S/E – constipation, urinary retention, dry mouth ROBINUL (GLYCOPYRROLATE) – similar to above USE – pre-op to decrease secretions, GI disorders S/E – similar to above SCOPOLAMINE PATCH – Classified as an antihistamine for motion sickness; Topical skin patch behind ear for 3 days USE – cruising in water, flying, car sickness S/E – dry mouth, visual disturbances due to pupil dilation THANK YOU Prof. Ruby D. Espares​ rdespares@bicol- u.edu.ph