N241 Neuro III F24 PDF

Chapter 13 CENTRAL NERVOUS SYSTEM STIMULANTS AND RELATED DRUGS  2 Very complex system in the human body Central Nervous CNS activity is regulated System by a “checks-and- balances system.” Excessive stimulation of...

Chapter 13 CENTRAL NERVOUS SYSTEM STIMULANTS AND RELATED DRUGS  2 Very complex system in the human body Central Nervous CNS activity is regulated System by a “checks-and- balances system.” Excessive stimulation of excitatory neurons or blockade of inhibitory neurons. Receptors in the CNS  CNS 3 Stimulants  CNS stimulant drugs act by stimulating the excitatory neurons in the brain.  Neurons contain receptors for excitatory neurotransmitters, including dopamine (dopaminergic drugs), norepinephrine (adrenergic drugs), and serotonin (serotonergic drugs).  Sympathomimetic drugs Classi&cation 4  Classi&ed according to  Chemical structural similarities: amphetamines, serotonin agonists, sympathomimetics, and xanthines  Site of therapeutic action in the central nervous system (CNS)  Majortherapeutic uses: anti–attention de&cit disorder, antinarcoleptic, anorexiant, antimigraine, and analeptic drugs  Attention De)cit Hyperactivity 5 Disorder (ADHD)  Most common psychiatric disorder in children, a;ecting 4% to 10% of school- age children of which approximately 6% are treated with medication  Boys are a;ected from three times more often than girls.  Primary symptoms of ADHD are inappropriate ability to maintain attention span or the presence of hyperactivity and impulsivity.  Drug therapy for both childhood and adult ADHD is the same.  6 Narcolepsy  Incurable neurologic condition in which patients unexpectedly fall asleep in the middle of normal daily activities. These “sleep attacks” are reported to cause car accidents or near-misses in 70% or more of patients..  Drugs for Attention De.cit Hyperactivity 7 Disorder (ADHD) and Narcolepsy  CNS stimulants are.rst line drugs.  Amphetamines: methylphenidate  Nonamphetamine stimulants  Atomoxetine: nonstimulant drug that is also used to treat ADHD  Moda.nil  indicated for improvement of wakefulness in patients with excessive daytime sleepiness associated with narcolepsy  Mechanism of Action and 8 Drug E5ects  Amphetamines  increase the e5ects of norepinephrine and dopamine in CNS synapses by increasing their release and blocking their reuptake. Then, noriepi & dop are in contact with their receptors longer, which lengthens their duration of action.  Stimulate areas of the brain associated with mental alertness  CNS e5ects  Mood elevation or euphoria  Increased mental alertness and capacity for work  Decreased fatigue and drowsiness  Prolonged wakefulness  Mechanism of Action and 9 Drug E5ects (Cont.)  Respiratory e5ects  Relaxation of bronchial smooth muscle  Increased respiration  Dilation of pulmonary arteries Indications/Contraindications 1 0 Indications: ADHD Narcolepsy Obesity Contraindications: Known drug allergy Cardiac structural abnormalities Recent MAOI usage  1 Adverse E)ects 1  Wide range; dose related  Tend to “speed up” body systems  Common adverse e)ects include:  Palpitations, tachycardia, hypertension, angina, dysrhythmias, nervousness, restlessness, anxiety, insomnia, nausea, vomiting, diarrhea, dry mouth, increased urinary frequency, others Principal Drugs Used to Treat 1 2 ADHD and Narcolepsy  Amphetamines  Amphetamine sulfate  Amphetamine aspartate (Adderall): one of the most commonly prescribed drugs for ADHD  Nonamphetamine stimulants  Atomoxetine: nonstimulant drug also used for ADHD  1 Atomoxetine (Strattera) 3  Approved for treating ADHD in children older than 6 years of age and in adults  Not a controlled substance  lacks addictive properties  In September 2005, the FDA issued a warning describing cases of suicidal thinking and behavior in small numbers of adolescent patients receiving this medication.  14 Methylphenidate (Ritalin) First prescription drug indicated for ADHD Also used for narcolepsy Extended-release dosage forms Ritalin SR Concerta Metadate CD Copyright © 2020 Elsevier Inc. All Rights Reserved.  1 Nursing Implications 5  Drugs for ADHD  Last daily dose should be given 4 to 6 hours before bedtime to reduce insomnia.  Take on an empty stomach 30 to 45 minutes before meals.  Drug “holidays” may be ordered.  Instruct parents to keep a journal to monitor the child’s response to therapy.  Monitor the child for continued physical growth, including height and weight.  1  6 of According to the National Institutes Health and the Centers for Disease Control and Prevention, approximately 35% of Americans are obese, and nearly two thirds (64.5%) are overweight.  More than 78 million obese adults Obesity  Many associated health risks  1  7 Any substance that suppresses appetite  Used to treat obesity  Anorexiants  Benzphetamine (Regimex)*  Methamphetamine (Desoxyn)* Anorexiant s *Only ones approved for treatment of obesity.  1  8 Suppress appetite control centers in the brain  Increase the body’s basal metabolic rate  Mobilization of adipose tissue stores  Enhanced cellular glucose uptake Mechanism  Reduce dietary fat absorption of Action  1 9  Orlistat (Xenical): related nonstimulant drug used to treat obesity Other  Mechanism of action: works locally in the small and large intestines, Drugs to where it inhibits absorption of caloric intake from fatty foods. Treat  Inhibits enzyme lipase  Reduces fat absorption by roughly Obesity 30%  Restricting dietary intake of fat to less than 30% of total calories can help reduce GI adverse eKects.  Oily spotting, Latulence, fecal incontinence  20 Indications Used to treat obesity along with behavior modi;cations (diet, exercise) Most often used in higher-risk patients Contraindications Indications/Contraindications of Anorexiants Drug allergy Severe cardiovascular disease Uncontrolled HTN Hyperthyroidism Eating disorders MAOI usage  21 Adverse  Possible elevated blood pressure and heart E)ects of palpitations Anorexiant  Anxiety s  Agitation  Dizziness  Headache  Orlistat: fecal incontinence with oily stools  2 2  Anorexiants  Follow instructions for diet and exercise.  Take in the morning. Nursing  Avoid ca>eine Implication  Fat-soluble vitamin supplementation may be needed. s Migraine 2 3  Common type of recurring headache, usually lasting from 4 to 72 hours  Typical features: pulsatile quality with pain that worsens with each pulse  Most commonly unilateral but may occur on both sides of the head  Associated symptoms: nausea, vomiting, photophobia (avoidance of light), and phonophobia (avoidance of sounds)  Aura Antimigraine Drugs 2 5  Antimigraine (serotonin agonists; also called triptans)  Sumatriptan (Imitrex)  Almotriptan (Axert) Mechanism of Action and Drug E5ects 26  Triptans  Stimulate 5-HT receptors in cerebral arteries, causing vasoconstriction and reducing headache symptoms  Reduce the production of inBammatory neuropeptides  Abortive therapy for migraines   Triptans Adverse  Vasoconstriction E)ects of  Irritation at injection Antimigraine site Drugs  Tingling, ects are comparable overall. Serotonin  Relief from moderate to severe migraines within 2 hours Receptor  Action: Agonists  Stimulate 5-HT1 receptors in the Sumatriptan brain; causing vasoconstriction  reduce the production of (Imitrex) inJammatory neuropeptides.  Oral, sublingual tablets, SC injection, and nasal sprays 28   Selective serotonin receptor agonists (SSRAs) or Triptans  Dissolvable wafers, nasal spray, and self-injectable Nursing forms Implication  ProvidespeciEc teaching s (Cont.) about correct administration.  Instruct patients to keep a journal to monitor response to therapy. 29 Monitor ADHD: decreased hyperactivity, increased attention span and concentration Anorexiant: appetite control and weight loss Narcolepsy: decrease in sleepiness Serotonin agonist: decrease in frequency, duration, and severity of migraines Monitor for adverse e@ects Nursing Implications Therapeutic Responses 30 ANTIEPILEPTIC DRUGS  32 Epilepsy  Syndrome of CNS dysfunction  Most common chronic neurologic illness  Results from excessive electrical activity of neurons located in superects Levetiracetam (Keppra) 48  Adjunct therapy for partial seizures with and without secondary generalization  Contraindication: known drug allergy  Mechanism of action: unknown  Adverse eAects: generally well tolerated, CNS  No drug interactions Safety: Look-Alike/Sound- 49 Alike Drugs  Be careful with drug names!  When using trade names, Cerebyx and Celebrex sound and look very much alike … but they are quite diDerent!  Use both trade and generic names when ordering medications. Nursing Implications of 5 1 Antiepileptic Drugs  Assessment  Health history, including current medications  Drug allergies  Liver function studies, complete blood count  Baseline vital signs   Oral drugs  Take regularly, same time each day. Nursing  Takewith meals to Implications reduce GI upset. of  Do not crush, chew, or Antiepileptic open extended-release forms. Drugs  Ifpatient is NPO for a procedure, contact prescriber regarding AED dosage. 52   Intravenous forms  Follow manufacturer’s recommendations for IV Nursing delivery—usually given slowly. Implications  Monitorvital signs of during administration. Antiepileptic  Avoid extravasation of Drugs @uids.  Use only normal saline with IV phenytoin (Dilantin). 53   Teach patients to keep a journal to monitor:  Response to AED Nursing  Seizure occurrence and Implications descriptions of  Adverse eDects Antiepileptic  Instruct patients to wear a Drugs medical alert tag or ID. (Cont.)  AEDs should not be discontinued abruptly.  Follow driving recommendations. 54   Teach patients that therapy is long term and possibly lifelong (not a cure).  Monitor for therapeutic e?ects: Nursing  Decreased or absent seizure activity Implications  Monitor for adverse e.ects: of  Mental status changes, mood Antiepileptic changes, changes in level of consciousness or sensorium Drugs  Eye problems, visual disorders (Cont.)  Sore throat, fever (blood dyscrasias may occur with hydantoins)  Many others 55 ANTIPARKINSON DRUGS Parkinson’s Disease (PD) 5  Chronic, 7 progressive, degenerative disorder  A9ects dopamine- producing neurons in the brain  Caused by an imbalance of two neurotransmitters  Dopamine  Acetylcholine (ACh) Copyright © 2020 Elsevier Inc. All Rights Reserved. Parkinson’s Disease 58 (Cont.)  Symptoms occur when about 80% of the dopamine stored in the substantia nigra of the basal ganglia is depleted.  Symptoms can be partially controlled as long as there are functioning nerve terminals that can take up dopamine.  A progressive condition  Rapid swings in response to levodopa occur (“on-o> phenomenon”)  PD worsens when too little dopamine is present.  Dyskinesia occurs when too much dopamine is present.  “Wearing-o> phenomenon”  PD-associated dementia   Di#culty in performing voluntary movements  Two common types: Dyskinesi  Chorea: irregular, spasmodic, involuntary movements of the a limbs or facial muscles  Dystonia: abnormal muscle tone leading to impaired or abnormal movements 61 Treatment of Parkinson’s 6 2 Disease Full Treatment explanation of centers on disease to the drug therapy patient PT, OT, Severe cases: speech Deep brain therapy stimulation important Pharmacology Overview 63 PD is thought to be caused by an imbalance of dopamine and Ach, with a de3ciency of dopamine in certain areas of the brain. Drug therapies are aimed at increasing the levels of dopamine or antagonizing the e=ects of Ach. Unfortunately, current drug therapy does not slow the progression of the disease but rather is used to slow the progression of symptoms. Indirect-Acting Dopaminergic Drugs: Monoamine Oxidase 65 Inhibitors  MAOIs break down catecholamines in the CNS, primarily in the brain.  Selegiline (Eldepryl) and rasagiline (Azilect) are selective MAO-B inhibitors.  Cause an increase in levels of dopaminergic stimulation in the CNS  Do not elicit the “cheese eJect” of the nonselective MAOIs used to treat depression (if 10 mg or less is used) Dopamine Modulator Amantadine (Symmetrel) Indirect acting  Causes release of  Used early; e;ective for only dopamine from storage 6 to 12 months sites in the presynaptic  Used to treat dyskinesia 5bers of nerve cells within associated with carbidopa- the basal ganglia levodopa  Blocks the reuptake of  Common adverse e;ects dopamine mild; dizziness, insomnia, and  Result: higher levels of nausea. dopamine in the synapses  Drug interactions: increased between nerves and anticholinergic adverse improved dopamine e;ects when given with neurotransmission anticholinergic drugs between neurons Dopamine Replacement Drugs 67  Replacement drugs (presynaptic)  Levodopa: biologic precursor of dopamine required by the brain for dopamine synthesis  Levodopa is able to cross the blood-brain barrier, and then it is converted to dopamine.  Replacement drugs  Carbidopa is given with levodopa.  Carbidopa does not cross the blood-brain barrier and prevents levodopa breakdown in the periphery.  As a result, more levodopa crosses the blood-brain barrier, where it can be converted to dopamine. Levodopa Therapy 6 8  Levodopa is taken up by the dopaminergic terminal, converted into dopamine, and then released as needed.  As a result, neurotransmitter imbalance is controlled in patients with early PD who still have functioning nerve terminals.  Ultimately, levodopa no longer controls the PD, and the patient is seriously debilitated.  This generally occurs between 5 and 10 years after the start of levodopa therapy.  Contraindicated in cases of angle-closure glaucoma  Use cautiously in patients with open-angle glaucoma  Adverse eGects: cardiac dysrhythmias, hypotension, chorea, muscle cramps, and GI distress Carbidopa-Levodopa 6 9 (Sinemet) Sinemet CR: increases “on” time and decreases “o