Drugs Affecting the Central Nervous System

CNS Depressants: Benzodiazepines A commonly prescribed drug class Favorable drug effect profiles, efficacy, and safety

Benzodiazepines Classified as either: Sedative-hypnotic Anxiolytic (medication that relieves anxiety)

Benzodiazepines: Sedative-Hypnotic Types Long-acting estazolam ,lorazepam Short-acting temazepam ,alprazolam

Benzodiazepines: Mechanism of Action Depress CNS activity Affect hypothalamic, thalamic, and limbic systems of the brain

Benzodiazepines: Drug Effects Calming effect on the CNS Useful in controlling agitation and anxiety Reduce excessive sensory stimulation, inducing sleep

Side effects Findout…

Benzodiazepines: Indications Sedation Sleep induction Skeletal muscle relaxation Anxiety relief Treatment of alcohol withdrawal

Sedative-Hypnotics: Barbiturates First introduced in 1903; were the standard drugs for insomnia and sedation Habit forming; low therapeutic index Only a handful commonly used today due in part to the safety and efficacy of benzodiazepines

Therapeutic Index Dosage range within which a drug is effective but above which it is rapidly toxic Barbiturates have a very narrow therapeutic index

Barbiturates: Mechanism of Action Site of action Brainstem (reticular formation) By inhibiting GABA, nerve impulses traveling in the cerebral cortex are also inhibited

Barbiturates: Drug Effects Low doses: sedative effects High doses: hypnotic effects (also lower respiratory rate) Notorious enzyme inducers Stimulate liver enzymes that cause metabolism or breakdown of many drugs Result in shortened duration of action

Barbiturates: Indications Hypnotics Sedatives Anticonvulsants Anesthesia for surgical procedures

Barbiturates: Adverse Effects Body System Adverse Effects CNS Drowsiness, lethargy, vertigo, mental depression, others Respiratory Respiratory depression, apnea, bronchospasms, cough

Barbiturates: Toxicity and Overdose Overdose frequently leads to respiratory depression and subsequent respiratory arrest Overdose produces CNS depression (sleep to coma and death)

phenobarbital secobarbital Common Barbiturates phenobarbital secobarbital

CNS Depressants: 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) Instruct patients to avoid alcohol and other CNS depressants

Nursing Implications (cont’d) Check with physician 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