Central Nervous System Depressants

1. Central Nervous System Depressants

2. CNS Depressants Sedatives • Drugs that have an inhibitory effect on the CNS to the degree that they reduce: • Nervousness • Excitability • Irritability • without causing sleep

3. CNS Depressants Hypnotics • Calm or soothe the CNS to the point that they cause sleep

4. CNS Depressants Sedative-Hypnotics—dose dependent: • At low doses, calm or soothe the CNS without inducing sleep • At high doses, calm or soothe the CNS • to the point of causing sleep

5. Sedative-Hypnotics: Barbiturates • First introduced in 1903, standard agents for insomnia and sedation • Habit-forming • Only a handful commonly used today due in part to the safety and efficacy of: BENZODIAZEPINES

6. Sedative-Hypnotics: Barbiturates Four categories: • Ultrashort • mephobexital, thiamylal, thiopental • Short • pentobarbital, secobarbital • Intermediate • aprobarbital, butabarbital • Long • phenobarbital

7. Sedative-Hypnotics: Barbiturates Barbiturates have a very narrow therapeutic index. Therapeutic Index • Dosage range within which the drug is effective but above which is rapidly toxic.

8. Sedative-Hypnotics: Barbiturates Mechanism of Action • Site of action: • Brain stem (reticular formation) • Cerebral cortex • By inhibiting GABA, nerve impulses traveling in the cerebral cortex are also inhibited.

9. Sedative-Hypnotics: Barbiturates Drug Effects • Low doses: Sedative effects • High doses: Hypnotic effects (also lowers respiratory rate) Notorious enzyme inducers

10. Sedative-Hypnotics: Barbiturates Therapeutic Uses • Hypnotics • Sedatives • Anticonvulsants • Surgical procedures

11. Sedative-Hypnotics: Barbiturates Side Effects Body System Effects CNS Drowsiness, lethargy, vertigo mental depression, coma Respiratory Respiratory depression, apnea, bronchospasms, cough

12. Sedative-Hypnotics: Barbiturates Side Effects Body System Effects GI Nausea, vomiting, diarrhea Other Agranulocytosis, vasodilation, hypotension, Stevens-Johnson syndrome

13. Sedative-Hypnotics: Barbiturates Toxicology • Overdose frequently leads to respiratory depression, and subsequently, respiratory arrest. • Can be therapeutic: • Anesthesia induction • Uncontrollable seizures: “phenobarbital coma”

14. Sedative-Hypnotics: Barbiturates 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

15. CNS Depressants: Benzodiazepines Most frequently prescribed sedative-hypnotics • Most commonly prescribed drug classes • Favorable side effects • Efficacy • Safety

16. CNS Depressants: Benzodiazepines Classified as either: • Sedative-hypnotic or Anxiolytic (Medication that relieves anxiety)

17. CNS Depressants: Benzodiazepines Sedative-Hypnotic Type • Long-Acting: • flurazepam (Dalmane), quazepam (Doral) • Short-Acting: • estazolam (Prosom), temazepam (Restoril), • triazolam (Halcion)

18. CNS Depressants: Benzodiazepines Anxiolytic Type • alprazolam (Xanax) • chloridiazepoxide (Librium) • diazepam (Valium) • lorazepam (Ativan) • midazolam (Versed) zolpidem (Ambien) and zaleplon (Sonata) (nonbenzodiazepine hypnotic agents, share characteristics)

19. CNS Depressants: Benzodiazepines Mechanism of Action • Depress CNS activity • Affect hypothalamic, thalamic, and limbic systems of the brain • Benzodiazepine receptors

20. CNS Depressants: Benzodiazepines Drug Effects • Calming effect on the CNS • Useful in controlling agitation and anxiety

21. CNS Depressants: Benzodiazepines Therapeutic Uses • Sedation • Sleep induction • Skeletal muscle relaxation • Anxiety relief • Treatment of alcohol withdrawal • Agitation • Depression • Epilepsy • Balanced anesthesia

22. CNS Depressants: Benzodiazepines Side Effects • Mild and infrequent Headache Drowsiness Dizziness Vertigo Lethargy Paradoxical excitement (nervousness) “Hangover effect”

23. CNS Depressants: Nursing Implications • Before beginning therapy, perform 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.

24. CNS Depressants: Nursing Implications • Give 15 to 30 minutes before bedtime for maximum effectiveness in inducing sleep. • Most benzodiazepines (except flurazepam) cause REM rebound and a tired feeling the next day; use with caution in the elderly. • Patients should be instructed to avoid alcohol and other CNS depressants.

25. CNS Depressants: Nursing Implications • Check with physician before taking any other medications, including OTC medications. • It may take 2 to 3 weeks to notice improved sleep when taking barbiturates. • Abruptly stopping these medications, especially barbiturates, may cause rebound insomnia.

26. CNS Depressants: Nursing Implications • Safety is important • Keep side rails up • Do not permit smoking • Assist patient with ambulation (especially the elderly) • Keep call light within reach • Monitor for side effects

27. CNS Depressants: Nursing Implications • Monitor for therapeutic effects • Increased ability to sleep at night • Fewer awakenings • Shorter sleep induction time • Few side effects, such as hangover effects • Improved sense of well-being because of improved sleep

29. Anticonvulsants and Drugs to Treat Other CNS Disorders

30. Chapter 8 Topics • Epilepsy • Parkinson’s Disease • Myasthenia Gravis • Attention-Deficit Disorders • Amyotrophic Lateral Sclerosis (ALS) • Multiple Sclerosis (MS) • Alzheimer’s Disease

31. Learning Objectives • Develop an understanding of the physiologic processes that occur in epilepsy. • Classify seizures and the goals of their therapy. • Understand that specific drugs are used in different classes of seizures.

32. Learning Objectives • Be familiar with Parkinson’s disease and the drugs used in its treatment. • Know the symptoms and treatments of • myasthenia gravis • attention-deficit disorders • amyotrophic lateral sclerosis • multiple sclerosis • Alzheimer’s disease

33. Epilepsy • Common neurologic disorder with sudden and recurring seizures • Caused by abnormal electrical impulses in the brain

34. Epilepsy • In the U.S., 2.5 million people are affected. • Not all seizure disorders are epilepsy.

35. Epilepsy Seizure Abnormal electrical discharges in the cerebral cortex caused by sudden, excessive firing of neurons • Result in a change in behavior of which the patient is not aware • While conscious, the patient may or may not lose movement control • Loss of body control may affect one area or the entire body

36. Epilepsy Causes of Seizures • Imbalance of excitatory and inhibitory neurotransmitters: • Glutamate – inhibitory • GABA – excitatory • Other neurotransmitters can be involved • Neurotransmitter levels are controlled by enzymes • Disruption in enzymes = disruption of neurotransmitters

37. Causes of Seizures ETOH withdrawal Cardiovascular disease High fever Hypocalcemia High or low blood sugar Hypoxia Infection (meningitis) Metabolic abnormalities Brain tumor Toxic substances Trauma or injury to the head Epilepsy

38. Epilepsy Classes of Seizures • Partial • Generalized

39. Epilepsy Classes of Seizures • Partial • Simple-partial • Complex-partial • Generalized

40. Epilepsy Classes of Seizures • Partial • Simple-partial • Complex-partial • Generalized • Tonic-clonic or grand mal • Absence or petit mal • Myoclonic • Atonic

41. Epilepsy Partial Seizures • Localized in a specific area of the brain • Occurs with 65% of epileptic patients • Can progress to generalized seizures

42. Epilepsy Partial Seizures • Simple-Partial • Complex-Partial

43. Epilepsy Partial Seizures • Simple-Partial • No loss of consciousness • May have muscle twitching or sensory hallucinations • Complex-Partial

44. Epilepsy Partial Seizures • Simple-Partial • No loss of consciousness • May have muscle twitching or sensory hallucinations • Complex-Partial • Impaired consciousness • With confusion, blank stare, and postseizure amnesia

45. Epilepsy Generalized Seizures • Involves both hemispheres of the brain, not one specific location • Types • Tonic-Clonic • Absense • Myoclonic • Atonic

46. Generalized Seizures Tonic-Clonic Seizures • Tonic – body becomes rigid, lasts a minute or less • Clonic – initiated with muscle jerks, and may be accompanied by shallow breathing, loss of bladder control, and excess salivation

47. Generalized Seizures Absence • Interruption of activities by blank stare, rotating eyes, uncontrolled facial movements, rapid eye blinking, and/or jerking of an arm or leg • No generalized convulsions • Usually lasts 30 seconds or less • Many times it progresses to tonic-clonic as the patient gets older

48. Generalized Seizures Myoclonic • Occurs with sudden, massive, brief muscle jerks or non-massive, quick jerks • Consciousness is not lost • Can occur during sleep

49. Generalized Seizures Atonic • Begins with sudden loss of muscle tone and consciousness • Muscles relax, limbs go limp • Lasts a few seconds to a minute, then patient can resume standing and walking

50. Generalized Seizures Status Epilepticus • Continuous tonic-clonic seizures with or without return to consciousness • High fever and lack of oxygen severe enough to cause brain damage or death