Central Nervous System Depressants Sedative Drugs that have an inhibitory effect on the CNS to the degree that they reduce: Nervousness, excitability, irritability Without causing sleep Hypnotics Calm or soothe the CNS to the point that they cause sleep Much more potent than sedatives 3 main groups Miscellaneous (cont d) Sedative-hypnotics dose dependent At low doses, calm the CNS without inducing sleep At high doses, calm the CNS to the point of causing sleep Sleep Normal sleep is cyclic and repetitive A sleeping person is unaware of sensory stimuli within the immediate environment Sleep architecture Rapid eye movement (REM) sleep Non-REM sleep Drug effects on sleep REM interference REM rebound First introduced in 1903; were the standard drugs for insomnia and sedation Produce many unwanted side effects Habit-forming Narrow therapeutic index Not many in clinical use today Due to the replacement with benzodiazepines : Four Categories Ultrashort-acting (i.e., thiopental -Pentothal) Anesthesia for short surgical procedures, other uses Short-acting (i.e., secobarbital) Sedation and control of convulsive conditions Intermediate-acting (i.e., butabarbitol) Sedation and control of convulsive conditions Long-acting (i.e., phenobarbital) Sleep induction, epileptic seizure prophylaxis 1
Mechanism of Action Site of action: Brain stem (reticular formation) Cerebral cortex Potentiates GABA Nerve impulses traveling in the cerebral cortex are also inhibited. Drug Effects Low doses: High doses: Sedative effects Notorious enzyme inducers Hypnotic effects (also lowers respiratory rate) Stimulate liver enzymes that cause metabolism or breakdown of many drugs Result in shortened duration of action Therapeutic Uses Hypnotics Sedatives Anticonvulsants Surgical procedures Anesthesia induction Provide anesthesia for short surgical procedures Status epilepticus Reduce ICP (neurosurgical patients) Side Effects: Body System Effects CNS Drowsiness, lethargy, vertigo mental depression, coma, reduced REM sleep (results in AGITATION, INABILITY TO DEAL WITH NORMAL STRES S Respiratory Respiratory depression, apnea, bronchospasms, cough * Nightmares can occur after drug stopped Side Effects Body System GI C/V Hematologic Other Effects Nausea, vomiting, diarrhea Vasodilation, hypotension, Agranulocytosis, thrombocytopenia Hypersensitivity reactions Stevens-Johnson syndrome Classroom Response Question An elderly patient taking multiple medications has a barbiturate added to his medication regimen. When administering a barbiturate to an elderly patient, the nurse should expect A. a decrease in dosages of the other medications. B. the patient will experience increased amounts of REM sleep. C. to administer half of the usual dose of the barbiturate. D. total relief of anxiety. 12 Copyright 2014 by Mosby, an imprint of Elsevier Inc. 2
Toxicology Overdose frequently leads to respiratory depression, and subsequently, respiratory arrest Can be therapeutic: Anesthesia induction Uncontrollable seizures Induce a phenobarbital coma : Toxicity and Overdose (cont d) Treatment of overdose NO REVERSAL AGENT Maintain adequate airway Assisted ventilation/oxygen therapy Fluids Pressor support Activated charcoal Drug Interactions Additive effects: ETOH, antihistamines, benzodiazepines, narcotics, tranquilizers Inhibited metabolism: MAOIs will prolong effects of barbiturates Increased metabolism: Reduces anticoagulant response, leading to possible clot formation Classroom Response Question have a low therapeutic index. This means A. low doses are not therapeutic. B. the toxic range is narrow. C. they are habit forming. D. the effective, safe dosage range is narrow. 16 Copyright 2014 by Mosby, an imprint of Elsevier Inc. Formerly the most commonly prescribed sedative-hypnotic drugs Nonbenzodiazepines currently more frequently prescribed Favorable drug effect profiles, efficacy, and safety Classified as either: Sedative-hypnotic Anxiolytic Medication that relieves anxiety 3
Sedative-Hypnotic Type Long-Acting: flurazepam (Dalmane), quazepam (Doral) Intermediate-acting alprazolam (Xanax), lorazepam (Ativan), temazepam (Restoril) Short-Acting: estazolam (Prosom), temazepam (Restoril), triazolam (Halcion), zolpidem (Ambien) Anxiolytic Type alprazolam (Xanax) chloridiazepoxide (Librium) diazepam (Valium) lorazepam (Ativan) midazolam (Versed) Mechanism of Action Depress CNS activity Affect hypothalamic, thalamic, and limbic systems of the brain Benzodiazepine receptors (located in the brain) Gamma-aminobutyric acid (GABA) inhibits stimulation Do not suppress rapid eye movement (REM) sleep as much as barbiturates do Do not increase metabolism of other drugs Drug Effects Calming effect on the CNS Useful in controlling agitation and anxiety Reduce excessive sensory stimulation, inducing sleep Induce skeletal muscle relaxation Indications Sedation Sleep induction Skeletal muscle relaxation Anxiety relief Treatment of alcohol withdrawal Agitation relief Anxiety related depression Treatment of acute seizure disorders Moderate/conscious sedation Side Effects - Mild and infrequent Fall hazard for elderly persons Headache Drowsiness, Lethargy Vertigo/Dizziness Amnesic effect Paradoxical excitement (nervousness) Hangover effect 4
Benzos: Toxicity and Overdose Somnolence Confusion Coma Diminished reflexes Do not cause hypotension and respiratory depression unless taken with other CNS depressants Treatment symptomatic and supportive Flumazenil as an antidote Classroom Response Question When providing education to the patient on the use of a benzodiazepine medication, the nurse will include which information? A. These medications have little effect on the normal sleep cycle. B. Using this medication may cause drowsiness the next day. C. It is safe to drive while taking this medication. D. These drugs are safe to use with alcohol. 26 Copyright 2014 by Mosby, an imprint of Elsevier Inc. Nonbenzodiazepine Hypnotics Share many characteristics of benzodiazepines Used to treat insomnia Examples: zaleplon (Sonata) fast onset (should be in/near bed) zolpidem (Ambien) eszoplicone (Lunesta) ramelteon (Rozerem) Eszoplicone and extended-release zolpidem (Ambien CR) approved for long-term therapy Nonbenzodiazepine Hypnotics Ramelteon (Rozerem) Mechanism Of Action Binds to melatonin MT1 and MT2 receptors, induces sleep (melatonin receptor agonist) Indication Long term treatment of insomnia Does not cause CNS depression No potential for abuse No withdrawal signs and symptoms Miscellaneous Agents Chloral hydrate (Noctec) Oldest miscellaneous sedative/hypnotic agent Favorable characteristics Potential disadvantage Tachyphylaxis Useful for only short-term therapy If mixed with ETOH Rapid loss of consciousness Known as a Mickey Finn Miscellaneous Agents Nonprescription drugs Sleeping aids Contain antihistamines Depressant effect on the CNS May also contain analgesics (aspirin or acetaminophen) Examples Doxylamine (i.e., Unisom) Diphenhydramine (i.e., Benadryl, Nytol, Sominex) Pyrilamine 5
Herbal Products: Valerian Herbal Products: Kava Used to relieve anxiety, restlessness, and sleep disorders May cause CNS depression, hepatotoxicity, nausea, vomiting, anorexia, restlessness, insomnia Many interactions, including with CNS depressants, MAOIs, phenytoin, warfarin, alcohol Contraindicated in cardiac and liver disease Patient should not operate heavy machinery during use Used to relieve anxiety, stress, and restlessness, and to promote sleep May cause temporary yellow skin discoloration (extended, continued intake) May cause visual disturbances Potential interactions with alcohol, barbiturates, and psychoactive drugs Contraindicated in liver disease, alcoholism, other conditions Patient should not operate heavy machinery during use Muscle Relaxants Act to relieve pain associated with skeletal muscle spasms Majority are central acting CNS is the site of action Similar in structure and action to other CNS depressants Direct acting Acts directly on skeletal muscle Closely resembles GABA Muscle Relaxants: Indications Relief of painful musculoskeletal conditions Muscle spasms Management of spasticity of severe chronic disorders Multiple sclerosis, cerebral palsy Work best when used along with physical therapy Muscle Relaxants: Indications (cont d) dantrolene (Dantrium) Chronic Spasticity From upper motor neuron disorders (e.g., spinal cord injury, stroke, cerebral palsy, or multiple sclerosis) Malignant hyperthermia Muscle Relaxants: Side Effects Extension of effects on CNS and skeletal muscles Euphoria Lightheadedness Dizziness Most common Drowsiness Fatigue Muscle weakness 6
Common Muscle Relaxants baclofen (Lioresal) cyclobenzaprine (Flexeril) dantrolene (Dantrium) metaxalone (Skelaxin) tizanidine (Zanaflex) Decreased incidence of CNS adverse effects carisoprodol (Soma) chlorzoxazone (Paraflex) methocarbamol (Robaxin) Classroom Response Question Which statement regarding muscle relaxants does the nurse identify as being accurate? A. Baclofen (Lioresal) is available as an injectable form for use with an implantable pump device. B. Cyclobenzaprine (Flexeril) produces little sedation. C. Patients taking muscle relaxants are at high risk to develop hypertension. D. Patients taking muscle relaxants should be told to stop taking the medication if they feel sleepy. Nursing Implications Before beginning therapy, obtain a thorough history regarding allergies, use of other medications, health history, and medical history Obtain baseline vital signs and I&O, including supine and erect BPs Assess for potential disorders or conditions that may be contraindications and for potential drug interactions Nursing Implications Give hypnotics 30 to 60 minutes before bedtime for maximum effectiveness in inducing sleep (depends on drug s onset) Most benzodiazepines cause REM rebound and a tired feeling the next day; use with caution in the elderly Instruct patients to avoid alcohol and other CNS depressants Nursing Implications (cont d) Check with prescriber before taking any other medications, including over-the-counter medications Rebound insomnia may occur for a few nights after a 3- to 4-week regimen has been discontinued Nursing Implications (cont d) Safety is important Keep side rails up or use bed alarms Do not permit smoking Assist patient with ambulation (especially the elderly) Keep call light within reach Monitor for adverse effects 7
Nursing Implications (cont d) Monitor for therapeutic effects Increased ability to sleep at night Fewer awakenings Shorter sleep-induction time Few adverse effects, such as hangover effects Improved sense of well-being because of improved sleep For muscle relaxants: Decreased spasticity, decreased rigidity IS EVERYONE RELAXED? 8