NUR 241 ADN PHARMACOLOGY Study Notes

NUR 241 ADN PHARMACOLOGY Study Notes

Learning Objectives

• Describe functions of the central nervous system (CNS)

• Contrast CNS depressant drugs and CNS stimulant drugs (refer to Chapter 13):

  • Basic actions and effects of both types of drugs

• Define key terms:

  • Hypnotic

  • Rapid Eye Movement (REM)

  • REM Sleep Interference

  • REM Rebound

  • Sedative

  • Sedative-Hypnotic

  • Sleep

  • Therapeutic Index

• Discuss causes of sleep disorders:

  • Psychological, physiological, environmental

• Identify specific drugs in CNS depressants:

  • Benzodiazepines

  • Nonbenzodiazepines

  • Muscle relaxants

  • Orexin receptor antagonists

  • Miscellaneous drugs

• Contrast medication aspects:

  • Mechanism of action

  • Indications

  • Adverse effects

  • Toxic effects

  • Cautions

  • Contraindications

  • Dosage forms

  • Routes of administration

  • Drug interactions

• Discuss the nursing process regarding CNS depressants and muscle relaxants.

• Develop nursing care plan for sleep disorder treatment using pharmacologic and nonpharmacologic approaches.

CNS Overview

• Functions of CNS:

  • Manages states of wakefulness and sleep

• Reticular Activating System (RAS):

  • Regulates wakefulness; activity decrease causes brain to transition to sleep, reducing sensory signals to the cortex.

  • CNS depressants enhance sleep by reducing RAS activity.

Sedatives and Hypnotics

• Definitions:

  • Sedatives:

  • Reduce nervousness, excitability, irritability

  • High doses may have hypnotic effects

  • Hypnotics:

  • Induce sleep, with a more potent effect than sedatives

  • Many drugs can act as both depending on dosage and patient, thus termed Sedative-Hypnotics.

Sleep Physiology

• Rapid-Eye Movement (REM) Sleep:

  • Comprises 25-35% of the sleep cycle

  • Characterized by vivid dreams and irregular breathing

  • Most crucial phase for brain reset.

Sleep Stages

• Non-REM Sleep Stages:

  • Stage 1:

  • Dozing feeling, easily awakened (2%-5%)

  • Stage 2:

  • Deeper sleep; higher arousal threshold (45%-50%)

  • Stage 3:

  • Deep sleep; difficult to awaken; vital signs decrease (10%-15%)

  • Stage 4:

  • Very difficult to wake; dreaming occurs; sleepwalking and bedwetting possible (25%-33%)

Causes of Sleep Disorders

• Psychological Factors:

  • Stress from work, relationships, and school

• Substance Use:

  • Drugs, both illicit and legal, including caffeine and certain prescriptions

• Alcohol Use:

  • Results in poor sleep quality

• Diet:

  • Avoidance of highly processed foods; limit excess sugar

• Poor Sleep Hygiene:

  • Includes cultural considerations, meditation, and herbal remedies

  • Ethnic differences in pharmacodynamics and pharmacokinetics

Knowledge Check 1

• A hospitalized patient has sleep difficulty. What should the nurse do first?

  1. Administer sedative-hypnotic if ordered.

  2. Offer valerian root tea.

  3. Encourage walking for exercise.

  4. Provide a restful environment and reduce noise.

Benzodiazepines

• Common Ending:

  • (-pam)

• Mechanism of Action (MOA):

  • Suppresses CNS via hypothalamus, thalamic, and limbic system interaction

  • Enhances gamma-aminobutyric acid (GABA) activity

• Uses:

  • Sedation, sleep aid, anxiolytic, acute seizure treatment, muscle relaxant, alcohol withdrawal management

• Risks:

  • CNS depressant effects, paradoxical excitement

  • Black Box warning for abuse and misuse, especially with opioid combination (risk of severe respiratory depression, coma, death).

• Antidote for Overdose:

  • Flumazenil (Romazicon)

• Interactions:

  • Effects increased by other CNS depressants, kava, valerian root, and grapefruit juice (cytochrome P-450 interaction)

• Classification:

  • Schedule IV controlled substance

Nonbenzodiazepines

• Notable Medications:

  • Zolpidem (Ambien):

  • Short-acting, lower daytime drowsiness incidence, risk for next-day impairment, somnambulism risk with CR formula

  • CR approved for long-term use

  • Eszopiclone (Lunesta):

  • FDA approved for long-term use, requires full 8 hours for sleep

  • Ramelteon (Rozerem):

  • Melatonin receptor agonist, not a CNS depressant, regulates circadian rhythm, contraindicated in severe liver dysfunction

Interactions

• Alcohol:

  • Increases CNS depression; dangerous with all medications

• Grapefruit:

  • Affects cytochrome P-450, increases drug duration and effects

• Valerian:

  • Increases CNS depressant effects.

New Drugs

• Suvorexant (Belsomra):

  • Orexin receptor antagonist that impacts neuropeptides promoting wakefulness

  • Adverse Effects:

  • Includes drowsiness, headache, dizziness, diarrhea, dry mouth, increased cholesterol, cough

  • More common side effects in women; includes daytime somnolence and unconscious nighttime behaviors

  • Classification:

  • Schedule IV controlled substance

Knowledge Check 2

• A patient presents with an oral benzodiazepine overdose. What is the nurse's immediate intervention?

  1. Prepare for hemodialysis.

  2. Administer flumazenil.

  3. Administer naloxone.

  4. Intubate and provide mechanical ventilation.

Barbiturates

• Classes:

  • Ultrashort acting

  • Short acting: Pentobarbital

  • Intermediate acting

  • Long acting: Phenobarbital

• MOA:

  • Acts on the reticular formation to inhibit cerebral cortex nerve impulses

  • Potentiates GABA

• Risks:

  • Many, considered less safe than benzodiazepines

  • Hypotension with rapid administration

  • Nausea, vomiting, diarrhea, hematologic effects, sedation, respiratory depression, cough, urticaria, angioedema, Stevens-Johnson syndrome (SJS)

Barbiturates Adverse Effects

• Respiratory Depression:

  • Occurs especially with rapid administration

• Hypotension:

  • Caution required in hemodynamically unstable patients

• Controlled Substance:

  • Requires written prescription; has a potential for abuse.

Enzyme Induction

• Effects of Enzyme Induction:

  • Increased metabolism: enzyme inducers impact cytochrome P-450, reducing efficacy of other drugs

• Interactions:

  • With drugs like rifampin and phenytoin

  • Additive CNS depression risk with alcohol, MAOIs, tricyclic antidepressants, anticoagulants, glucocorticoids, and oral contraceptives

Knowledge Check 3

• For a patient taking phenobarbital for seizure disorder, what is the priority instruction?

  1. Avoid alcohol use.

  2. Only take the medication when sensing a seizure.

  3. Stop medication if experiencing drowsiness.

  4. Take with antacid to reduce upset.

Muscle Relaxants

• Mechanism of Action:

  • Centrally-acting at CNS level

  • Depresses CNS activities at brainstem, thalamic, and basal ganglia levels

• Drugs:

  • Baclofen (Lioresal):

  • Available orally and injectable (baclofen pump)

  • Cyclobenzaprine (Flexeril):

  • Most common muscle spasm drug

  • Dantrolene:

  • Direct muscle relaxant, acting on excitation-contraction coupling, reducing muscle calcium release from sarcoplasmic reticulum

Muscle Relaxants Adverse Effects

• Sedation:

• Caution required:

  • No driving until effects are tolerated; assess cognition and effects

• Risk for Weakness and Unsteady Gait:

• Safety Precautions:

  • Monitor for falls

Nursing Process

• Assessment:

  • Review allergies, neurological, cardiovascular, pulmonary, hepatic function, sleep patterns, vital signs, and medication history.

• Implementation:

  • Ensure safety by advising against alcohol, assessing for hangover effects, and monitoring for respiratory depression.

  • Promote slow position changes to prevent falls; reinforce good sleep habits.

Knowledge Check 4

• Monitor a patient on muscle relaxant for which adverse effect?

  1. CNS depression

  2. Hypertension

  3. Peripheral edema

  4. Blurred vision

Exit Ticket

• Complete the handout

Emergency Response

• Document actions when Glasgow Coma Scale (GCS) is less than 8.