Drugs Affecting Autonomic NS (PDF)

PRELIMS: NCMA 216 (PHARMACOLOGY) Increase muscle tone - MODULE #5: DRUGS AFFECTING — ChEls are indirect-acting A...

PRELIMS: NCMA 216 (PHARMACOLOGY) Increase muscle tone - MODULE #5: DRUGS AFFECTING — ChEls are indirect-acting AUTONOMIC NS | VENJULLIAN. parasympathomimetic drugs that stimulates the parasympathetic nervous system AUTONOMIC NERVOUS SYSTEM. — These are chemicals that prevent the breakdown of the neurotransmitter acetylcholine or butyrylcholine. This increases the amount of the acetylcholine or butyrylcholine in the synaptic cleft that can bind to muscarinic receptors, nicotinic receptors and others. SYMPATHETIC AND PARASYMPATHETIC SYMPATHETIC DEPRESSANTS Sympatholytics (Adrenergic Blockers, SYMPATHETIC STIMULANTS Adrenolytics, or Adrenergic Antagonists) Sympathomimetics (Adrenergics, Action: Body Part Sympathetic Parasympathetic Adrenomimetics, or Adrenergic Agonists) Response response Decrease pulse rate Action: Decrease blood pressure Increase blood pressure Constrict bronchioles Eye Dilates pupil Constrict pupil Increase pulse rate Relax bronchioles PARASYMPATHETIC DEPRESSANTS Lungs Dilates bronchioles Constricts bronchioles and Dilate pupils of eyes Parasympatholytics (Anticholinergics, increases secretions Relax uterine muscles Cholinergic Antagonists, or Antispasmodics) Increase blood sugar Heart Increases HR Decreases HR Action: Increase pulse rate PARASYMPATHETIC STIMULANTS Decrease mucous secretions Blood vessels Constricts blood Dilates blood Direct-Acting Parasympathomimetics vessels vessels Decrease gastrointestinal motility (Cholinergics or Cholinergic Agonists) Increase urinary retention G.I. Relaxes smooth Increases peristalsis Action: Dilate pupils of eyes muscles of G.I Decrease blood pressure Decrease pulse rate ADRENERGIC AGONISTS AND Bladder Relaxes bladder Constricts bladder Constrict bronchioles ADRENERGIC BLOCKERS. Constrict pupils of eyes Uterus Relaxes Uterine —------ These are two groups of drugs that affect the Increase urinary contraction muscle sympathetic nervous system. Increase peristalsis Salivary —------- Increases salivation ADRENERGIC AGONISTS Gland INDIRECT-ACTING Drugs that stimulate the sympathetic nervous Cholinesterase Inhibitors (Anticholinesterase) system are called adrenergics, adrenergic Action: agonists, or sympathomimetics — mimic the sympathetic neurotransmitters Two enzymes that inactivate norepinephrine are High doses can cardiac dysrhythmias and norepinephrine and epinephrine. 1. Monoamine Oxidase (MAO) - inside renal vasoconstriction — act on one or more adrenergic receptor sites 2. Catechol-O-Methyltransferase (COMT)- located in the effector cells of muscles such as outside DOBUTAMINE - it acts at both receptor sites, the heart, bronchiole walls, GI tract, urinary has a slight preference for betal-receptor sites. bladder, and ciliary muscle of the eye. Drugs can prolong the action of the It is used in the treatment of heart failure neurotransmitter because it can increase myocardial 1. inhibiting the norepinephrine reuptake contractility 2. inhibiting the degradation by enzyme Without much change in rate and does not action. increase the oxygen demand of the cardiac muscle, an advantage over all of the other 1. ALPHA- AND BETA-ADRENERGIC AGONISTS sympathomimetic. drugs. Drugs that are generally sympathomimetic are called alpha-agonists (stimulate alpha-receptors) EPHEDRINE - stimulates the release of and beta - agonists (stimulate beta-receptors). norepinephrine from nerve endings and acts — Agonists stimulate all of the adrenergic directly on adrenergic receptor sites receptors, that is, they affect both alpha- and treatment of shock to chronic management beta-receptors of asthma and allergic rhinitis — Indicated for the treatment of hypotensive states or shock, bronchospasm, and some types of METARAMINOL - is very similar to asthma. norepinephrine. It is given as a single parenteral injection to DOPAMINE - choice for the treatment of shock. prevent hypotension by increasing It stimulates the heart and blood pressure myocardial contractility and causing (correct hypotension) increases blood peripheral vasoconstriction. flow to the kidney Its use is limited to situations in which dopamine or norepinephrine cannot be used EPINEPHRINE - used in emergencies to treat anaphylaxis Nursing Considerations For Patients Receiving a potent inotropic(strengthens myocardial Alpha And Beta - Adrenergic Agonist contraction) drug that increases cardiac — Assess vital signs, especially pulse and blood Inactivation of Neurotransmitters output pressure, to monitor for possible excess Transmitters are inactivated by: Promotes vasoconstriction stimulation of the cardiac system; 1. Reuptake of the transmitter back into the Systolic blood pressure elevation — Obtain an electrocardiogram (ECG) to neuron (nerve cell terminal) Increases heart rate evaluate for possible arrhythmias. 2. Enzymatic transformation or degradation. Produces bronchodilation. 3. Diffusion away from the receptor. — Note respiratory rate and auscultate lungs for Leading to peripheral vasoconstriction and beta2-adrenergic receptors, so the response is adventitious sounds to evaluate effects on bronchi an increase in vascular tone and blood relaxation of bronchial smooth muscle and and respirations. pressure. bronchodilation. — Monitor urine output to evaluate perfusion of — Action is more selective (activates only the the kidneys and therapeutic effects. beta2 receptors). — Monitor the results of laboratory tests, such as CLONIDINE - specifically stimulates central — By using selective sympathomimetics, fewer renal and liver function tests, to determine the nervous system (CNS) alpha2-receptors. undesired adverse effects will occur. need for possible dose adjustment Leads to decreased sympathetic outflow — However, high doses of albuterol may affect from the CNS because the beta1 receptors, causing an increase in heart rate. 2. ALPHA-SPECIFIC ADRENERGIC alpha2-receptors moderate the release of AGONISTS norepinephrine from the nerve axon. ADRENERGIC BLOCKERS. Alpha-specific adrenergic agonists, or alpha - Oral and transdermal forms for use to agonists - are drugs that bind primarily to control hypertension ADRENERGIC BLOCKING ANTAGONISTS alpha-receptors rather than to beta-receptors. Cause extreme hypotension, heart failure, Adrenergic blocking agents block the effects of Three drugs belong to this class: and bradycardia the sympathetic nervous system (SNS). 1. Clonidine (Catapres) — Nonselective adrenergic blocking agents block 2. Midodrine (ProAmatine) METHYLDOPA (ALDOMET) - is an all receptors, that is, both alpha- and 3. Phenylephrine (Neo-Synephrine, Allerest, alpha-adrenergic agonist (sympathomimetic) that beta-receptors. AK-Dilate, and others). acts within the CNS — Selective adrenergic blocking agents have specific affinity for alpha- or beta-receptors or for — Stimulation of alpha-receptors within the SNS 3. BETA-SPECIFIC ADRENERGIC specific alpha1-, beta1-, or beta2-receptor sites. uses are varied, depending on the specific drug AGONIST — Blocking all of the receptor sites within the and the route of administration Used to manage and treat bronchial spasm, SNS results in a lowering of blood pressure. asthma, and other obstructive pulmonasy PHENYLEPHRINE - potent vasoconstrictor conditions. 1. NONSELECTIVE ADRENERGIC and alpha1 - agonist with little or no effect on the These drugs includes: BLOCKING AGENTS heart or bronchi used in many combination cold 1. Albuterol (Proventil) Drugs that block both alpha- and beta-adrenergic and allergy products. 2. Bitolterol (Tornalate) receptors Topically it is used to treat allergic rhinitis 3. Isoetharine (generic) — Are primarily used to treat cardiac-related and to relieve the symptoms of otitis 4. Levalbuterol (Xopenex) conditions. media. 5. Metaproterenol (Alupent) — Results in lower blood pressure, slower pulse Ophthalmically it is used to dilate the 6. Pirbuterol (Maxair), rate, and increased renal perfusion with decreased pupils for eye examination, before surgery 7. Salmeterol (Serevent) renin levels. 8. Terbutaline (Brethaire) — Most of these drugs are indicated to treat MIDODRINE - an oral drug that is used to treat essential hypertension, alone or in combination orthostatic hypotension in patients who do not ALBUTEROL SULFATE (PROVENTIL) - a with diuretics respond to traditional therapy. beta2-adrenergic agonist, is selective for LABETALOL - is a newer drug that is used — Used for a wide range of conditions, including 3. BETA1 - SELECTIVE ADRENERGIC intravenously (IV) and orally to treat hypertension, migraines, angina, and essential BLOCKING AGENTS hypertension. It also can be used with Diuretics tremors They do not block the sympathetic — To prevent reinfarction after Myocardial bronchodilation that is so important for patients AMIODARONE - which is available in oral and Infarction with lung diseases or allergic rhinitis IV forms, is saved for serious emergencies and — For patients who smoke or who have asthma only used as an antiarrhythmic Prompts non-selective blockade of all or any other obstructive pulmonary disease, or beta-receptors results in a loss of the reflex seasonal or allergic rhinitis. CARVEDILOL - is only available orally and is bronchodilation that occurs with sympathetic — Also used for treating hypertension, angina used to treat hypertension, as well as heart failure stimulation. and some cardiac arrhythmias. and left ventricular dysfunction after myocardial — This limits the use of these drugs in patients These drugs includes: condition who smoke or have allergic or seasonal rhinitis, 1. Acebutolol (Sectral) asthma, or COPD. 2. Atenolol (Tenormin) 2. ALPHA1 - SELECTIVE ADRENERGIC These drugs includes: 3. Betaxolol (Kerlone, Betoptic), BLOCKING AGENTS 1. Carteolol (Cartrol) 4. Bisoprolol (Zebeta) Drugs that have a specific affinity for 2. Nadolol (Corgard) 5. Esmolol (Brevibloc) alpha1-receptors. 3. Nebivolol (Bystolic) 6. Metoprolol (Lopressor, Toprol XL). — Used to treat hypertension (vasodilation) and 4. Penbutolol (Levator) are often used to treat BPH because of their 5. Pindolol (Visken) CHOLINERGIC AGONISTS AND relaxing effects on the bladder and prostate 6. Propranolol (Inderal) ANTICHOLINERGIC AGENTS. 7. Sotalol (Betapace, Betapace AF) ALFUZOSIN (UROXATRAL) - Treatment of 8. Timolol (Blocadren, Timoptic). CHOLINERGIC AGONISTS benign prostatic hyperplasia Act at the same site as the neurotransmitter DOXAZOSIN (CARDURA) - Treatment of PROPRANOLOL - is very effective in blocking acetylcholine (ACh) and increase the activity of hypertension and BPH, all of the beta - receptors in the SNS and was one the ACh receptor sites throughout the body PRAZOSIN (MINIPRESS) - Treatment of of the first drugs of the class — produces a response similar to what is seen hypertension, when the parasympathetic system is activated, TAMSULOSIN (FLOMAX) - Treatment of NEBIVOLOL - is the newest adrenergic blocker often called Parasympathomimetic whose ВРН available and is not associated with the variety of action mimics the action of the parasympathetic TERAZOSIN (HYTRIN) - Treatment of adverse effects seen with propranolol use. nervous system. hypertension and BPH — Undesirable systemic effect - action of these TIMOLOL AND CARTEOLOL - are available drugs cannot be limited to a specific site, their 3. BETA - ADRENERGIC BLOCKING as an ophthalmic form of the drug for reduction effects can be widespread. AGENTS of intraocular pressure in patients with Beta-blockers are drugs used to block the open-angle glaucoma. beta-receptors within the SNS. — this drug is used topically, eye muscle relaxation occurs. 1. DIRECT-ACTING CHOLINERGIC 2. INDIRECT-ACTING CHOLINERGIC ANTICHOLINERGICS/PARASYMPATHOLYTICS AGONISTS AGONISTS Anticholinergics are drugs that oppose the effects Occupy receptor sites for ACh on the membranes Cause increased stimulation of the ACh receptor of acetylcholine. of the effector cells of the post - ganglionic sites by reacting with the enzyme — Block the effects of parasympathetic nervous cholinergic nerves, causing increased stimulation acetylcholinesterase and preventing it from system (PNS) so they are also called of the cholinergic receptor. breaking down the ACh that was released from parasympatholytics. — Drugs usually stimulate muscarinic receptors the nerve. — ATROPINE is currently the only widely used within the parasympathetic system. anticholinergic drug. — Used as systemic agents to increase bladder MYASTHENIA GRAVIS is an autoimmune — Other common examples include Meclizine, tone, urinary excretion, and gastrointestinal (Gl) disease characterized by antibodies to the ACh Scopolamine and Ipratropium. secretions and as ophthalmic agents to induce receptors. miosis to relieve the increased intraocular — This results in a loss of ACh receptors and Therapeutic Action pressure of glaucoma eventual loss of response at the neuromuscular Competitively blocking the ACh receptors at — Agents are used infrequently today because of junction. muscarinic cholinergic receptor sites that are their widespread parasympathetic activity. responsible for mediating the effects of the — Systemic absorption usually does not occur ACETYLCHOLINESTERASE INHIBITORS parasympathetic postganglionic impulses. when these drugs are used ophthalmically. are used to treat myasthenia gravis because they These drugs include: allow the accumulation of ACh in the synaptic ATROPINE - the prototype drug, is derived 1. Bethanechol (Duvoid, Urecholine) cleft, prolonging stimulation of any ACh sites from the plant belladonna 2. Carbachol (Miostat) that remain. — It is used to depress salivation and bronchial 3. Cevimeline (Evoxac) — Pyridostigmine- a medication that treats secretions and to dilate the bronchi, but it can 4. Pilocarpine (Pilocar). myasthenia gravis thicken respiratory secretions (causing obstruction of airways). CARBACHOL - is an ophthalmic agent used to ALZHEIMER DISEASE is a progressive induce miosis or pupil constriction. dementia characterized by a loss of IPRATROPIUM - Maintenance treatment of — It can relieve the increased intraocular ACh-producing neurons and ACh receptor sites bronchospasm associated with chronic pressure of glaucoma. in the neurocortex. obstructive pulmonary disease (COPD); PILOCARPINE - bind to muscarinic receptors ACETYLCHOLINESTERASE INHIBITORS SCOPOLAMINE - Decreases nausea and throughout the body cross the blood-brain barrier are used to manage vomiting associated with motion sickness; — Used to increase secretions in the mouth and Alzheimer disease by increasing ACh levels in decreases Gl secretions; GI tract and relieve symptoms of dry mouth; the brain and slowing the progression of the treatment of increased intraocular pressure disease. — Donepezil (Aricept) - Medicine used in the management of Alzheimer dementia