Mosby items and derived items © 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Chapter 22 Drugs Affecting the Central Nervous System

Mosby items and derived items © 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Neurotransmitters  Cause electrical depolarization and passage of signal to next neuron  Most are returned to releasing nerve terminal and “recycled”

Mosby items and derived items © 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Neurotransmitters (cont’d)  Factors impacting effect:  Amount released  Type/quantity of transport proteins  Previous release  Modifiers present  Reuptake process  Modulating interneurons

Mosby items and derived items © 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Psychiatric Medications  Antidepressants  Selective serotonin reuptake inhibitors (SSRIs) are first-line treatment  Newer: Serotonin norepinephrine reuptake inhibitors  Depression

Mosby items and derived items © 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Psychiatric medications (cont’d)  Mood stabilizers  Used primarily for bipolar disorder Alternating depression/mania (or hypomania) Alternating depression/mania (or hypomania)  Drugs: lithium, valproic acid, carbamazepine, gabapentin, lamotrigine, and antipsychotics  Main side effect is sedation

Mosby items and derived items © 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Psychiatric medications (cont’d)  Antipsychotics  Increase dopamine levels in brain  Psychotic disorders Impaired reality Impaired reality Schizophrenia Schizophrenia Psychosis associated with depression or mania Psychosis associated with depression or mania

Mosby items and derived items © 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Psychiatric medications (cont’d)  Antipsychotics (cont’d)  Newer agents more tolerable Risperidone Risperidone Olanzapine Olanzapine Quetiapine Quetiapine

Mosby items and derived items © 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Psychiatric medications (cont’d)  Drugs for Alzheimer’s dementia: cholinesterase inhibitors  Increase acetylcholine levels in brain  Drugs: Donepezil Donepezil Tacrine Tacrine Galantamine Galantamine Rivastigmine Rivastigmine  May cause gastrointestinal (GI) side effects

Mosby items and derived items © 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Psychiatric medications (cont’d)  Anxiolytics  Also used as amnesics  May augment opioid respiratory depression  Benzodiazepines Hyperpolarize neurons Hyperpolarize neurons Good for anesthesia induction Good for anesthesia induction Prevent “unpleasant recall” Prevent “unpleasant recall” Terminate seizures/increase threshold Terminate seizures/increase threshold

Mosby items and derived items © 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Psychiatric Medications (cont’d)  Barbiturates  Toxic potential and rapid tolerance Depress neuron activity Depress neuron activity High risk of addiction and abuse High risk of addiction and abuse  Used for Anesthesia induction Anesthesia induction Hypnotics Hypnotics seizures seizures

Mosby items and derived items © 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Psychiatric Medications (cont’d)  Other hypnotics  Often used to induce sleep  Hypnotics to induce sleep are generally recommended for 1 to 2 weeks  Eszopiclone New drug New drug Approved for long-term use Approved for long-term use

Mosby items and derived items © 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Ethyl Alcohol  Socially acceptable nonprescription sedative- hypnotic  Also has disinhibiting effect  In excess = general anesthetic  400 to 600 mg/dl = respiratory arrest  Delirium tremens  CNS hyperactivity on withdrawal

Mosby items and derived items © 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Pain Treatment  Pain is now the fifth vital sign  The pain experience  Pain Input from CNS pain receptors Input from CNS pain receptors  Suffering Emotional response to pain experience Emotional response to pain experience

Mosby items and derived items © 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Pain Treatment (cont’d)  Nonsteroidal antiinflammatory drugs (NSAIDs)  Affect hypothalamus and inhibit production of inflammatory mediators at pain site  Some may cause gastric irritation/ulceration  Salicylates are oldest (aspirin)  Acetaminophen (Tylenol)

Mosby items and derived items © 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Pain Treatment (cont’d)  Opioid analgesics  Derivatives of naturally occurring opium  Used to treat moderate to severe pain  Exert effect by binding to receptors for endogenous opioids (endorphins and enkephalins)  Popular drugs of abuse

Mosby items and derived items © 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Pain Treatment (cont’d)  Routes of opioid administration  As needed (by nurse)  Patient-controlled analgesia (PCA) pumps Better to keep control of pain than regain control Better to keep control of pain than regain control  Opioid inhalation Decreases dyspnea in advanced respiratory failure Decreases dyspnea in advanced respiratory failure Has shown good clinical effect on cancer patients without lung disease Has shown good clinical effect on cancer patients without lung disease

Mosby items and derived items © 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Pain Treatment (cont’d)  Local anesthetics  Interrupt nerve signals (pain) from damaged area Block Na channels along nerve cells Block Na channels along nerve cells  Also useful as analgesia and for terminating cardiac conduction abnormalities  Can suppress irritant tracheal cough response

Mosby items and derived items © 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Pain Treatment (cont’d)  Epidural analgesia  Infusions of local anesthetics/opioids improve postoperative pain therapy and outcome  Provides better pain control versus systemic analgesics

Mosby items and derived items © 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Pain Treatment (cont’d)  Combinations of analgesic classes  Prescription combinations of NSAIDs and opioids are widely available  Separate dosing may prove better with various side effects, toxicities, and half-lives More troublesome for patients to take independently More troublesome for patients to take independently

Mosby items and derived items © 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Chronic Pain Syndromes  Central sensitization can occur secondary to acute pain from surgery or trauma  Hyperesthesia, hyperpathia, and allodynia  Treatment during acute phase may reduce likelihood of neuropathic problem later

Mosby items and derived items © 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Chronic Pain Syndromes (cont’d)  Characteristics of neuropathic pain  Evidence of primary injury  Pain involving body area with sensory loss  Pain characterized as burning, electric, or shooting  Dysesthesias in the area  Sympathetic hyperactivity  Hyperalgesia, hyperpathia, and allodynia

Mosby items and derived items © 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Anesthesia  Drug-induced absence of perception  Usually inhaled or IV  Gases and volatile liquids  Depth is determined by response to painful stimuli  Change in heart rate or blood pressure

Mosby items and derived items © 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Anesthesia (cont’d)  Conscious sedation  Patient remains conscious Able to communicate and protect airway Able to communicate and protect airway Ability may be lost during procedure Ability may be lost during procedure  Goal is improved patient comfort and outcome  Conscious sedation standards are required by Joint Commission on Accreditation of Healthcare Organizations (JCAHO)

Mosby items and derived items © 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Anesthesia (cont’d)  Standards for providing conscious sedation  Resuscitation equipment and trained personnel immediately available  Conscious sedation requires >1 person  Deep sedation/general anesthesia require at least 3 people

Mosby items and derived items © 2008, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. CNS and Respiratory Stimulants  Analeptic drugs  Increase activity of brain  Treat: narcolepsy, attention-deficit hyperactivity disorder (ADHD), obesity  No clinical role in treating respiratory failure