Anxiolytic and Hypnotic Drugs

Objectives

• Identify and memorize:
  • Therapeutic uses, adverse effects, contraindications, drug–drug interactions, withdrawal concerns, and nursing considerations for benzodiazepines and barbiturates.
  • Key characteristics of other hypnotic/anxiolytic agents (Buspirone, diphenhydramine, “Z-drugs”).

Key Concepts & Terminology

• Anxiolytic: any drug that decreases anxiety.

• Hypnotic: drug that produces sleep; acts primarily on the reticular activating system (RAS).

• Sedation: loss of awareness/reduced reaction to external stimuli, but arousable (pre-hypnotic state).

• Dependence vs addiction: physiologic need vs compulsive use; both possible for CNS depressants.

• Paradoxical excitement: opposite reaction (agitation, insomnia, euphoria) instead of sedation.

• Black Box Warning (BBW): FDA’s most serious warning; opioids + benzos ↑ fatal respiratory depression.

• Withdrawal syndrome: cluster of symptoms when drug is stopped abruptly (headache, vertigo, nightmares, seizures, etc.).

Common Clinical Uses of CNS Depressant Classes

• Anxiety disorders (GAD, panic, situational stress)

• Acute agitation or hyper-excitability

• Alcohol withdrawal (to blunt autonomic surge & seizures)

• Seizure treatment and prevention

• Pre-op sedation / anesthesia adjunct

• Muscle relaxation (diazepam)

• Insomnia (short-term)

Benzodiazepines

Prototype/Key Agents (-pam / ‑lam)

• alprazolam (Xanax) – PO only

• clonazepam (Klonopin) – PO only

• chlordiazepoxide (Librium) – PO (classic for alcohol withdrawal)

• diazepam (Valium) – PO/IM/IV; also muscle relaxant; anesthesia induction

• lorazepam (Ativan) – PO/IM/IV; first-line status epilepticus

Mechanism of Action

• Potentiate gamma-aminobutyric acid (GABA) binding at GABA$_A$ receptor → $\uparrow$ chloride influx → neuronal hyper-polarization → CNS depression.

Therapeutic Indications

• Relief of acute/chronic anxiety

• Seizure control/prevention (esp. diazepam, lorazepam, clonazepam)

• Alcohol withdrawal syndrome

• Muscle spasm relief (diazepam)

• Sedation/anxiolysis pre-procedure

• Adjunct in anesthesia (diazepam)

Adverse Effects

• CNS: drowsiness, ataxia, confusion, “hangover,” dependence/addiction, paradoxical excitement, seizures on abrupt stop

• Respiratory: dose-dependent respiratory depression (potentiated by other CNS depressants)

• CVS: $\downarrow$ BP, $\downarrow$ HR, possible prolonged QT

• GI/GU: N/V, constipation, urine retention

• Other: vertigo, malaise, nightmares

• Withdrawal: headaches, nausea, vertigo, malaise, nightmares, seizures

Drug–Drug & Synergistic Interactions

• Alcohol, opioids – synergistic CNS/respiratory depression

• Other CNS depressants (antihistamines, barbiturates, antipsychotics)

• Cimetidine, oral contraceptives may prolong half-life (CYP inhibition)

Contraindications & Precautions

• Absolute: pregnancy & lactation (teratogenic), acute alcohol intoxication, shock, coma, severe respiratory depression

• Relative/caution:
  • BBW – concomitant opioid therapy
  • Elderly (↑ sensitivity, fall risk)
  • Hepatic/renal impairment
  • History of substance use disorder

Nursing Considerations

• Assess baseline VS, level of consciousness (LOC), anxiety scale

• IV route: give SLOW IV PUSH; monitor for $\downarrow$ RR/BP; keep patient in bed minimum 3 h post-IV

• Implement fall precautions; side rails ↑; assist with ambulation

• Continuous pulse oximetry if high-dose or combined depressants

• Do NOT mix in same syringe/line with opioids or other CNS depressants

• Taper dose gradually over days–weeks to avoid withdrawal seizures

• Reversal agent: flumazenil (Romazicon) IV; competitive antagonism at benzodiazepine receptor; monitor for re-sedation & seizures post-antidote

Patient Education

• Illegal & unsafe: driving or operating machinery under influence

• NO alcohol, opioids, or other benzos concurrently

• High addiction potential – take exactly as prescribed, short term

• Never stop abruptly; contact HCP to taper

• Report paradoxical excitement, severe dizziness, breathing difficulty, or signs of withdrawal

Barbiturates

Prototype/Key Agents (-barbital)

• butabarbital (Butisol)

• pentobarbital (Nembutal)

• phenobarbital (long-acting)

• secobarbital (Seconal)

Mechanism of Action

• Enhance GABA duration of chloride channel opening at GABA$_A$ receptor (different site vs benzos) → profound CNS depression; high doses also depress glutamate.

Therapeutic Indications

• Seizure control (phenobarbital)

• Acute manic states

• Short-term relief of anxiety

• Pre-operative sedation

• Euthanasia/medically induced coma (high doses)

Adverse Effects

• CNS: profound sedation, confusion, lethargy, vertigo, hallucinations, dependence/addiction, paradoxical excitement, “hangover”

• Respiratory: marked depression (dose-dependent)

• CVS: bradycardia, hypotension

• GI: N/V

• Dermatologic (rare): Stevens–Johnson Syndrome

• High fatal overdose risk – very narrow therapeutic window

Drug–Drug Interactions

• Additive CNS depression with alcohol, antihistamines, benzos, opioids

• Induce hepatic CYP450 → ↓ efficacy of oral anticoagulants, contraceptives, corticosteroids, doxycycline, etc.

Contraindications & Precautions

• Absolute: pregnancy, prior addiction history, severe hepatic/renal dysfunction, respiratory compromise, marked CNS depression, porphyria

• Avoid abrupt cessation in seizure disorders (rebound seizures)

• Use caution: chronic cardiac or respiratory disease, geriatric patients (↑ sensitivity)

Nursing Considerations

• Similar to benzodiazepines but more intense monitoring

• SLOW IV PUSH; have resuscitation equipment ready

• Continuous VS (BP, HR, RR); monitor for apnea

• Implement seizure precautions if tapering

• Taper gradually; abrupt stop → delirium, seizures, death

Patient Education

• Same core messages: no driving, alcohol, opioids, or abrupt discontinuation

• Inform about possible “hangover” feeling & hallucinations

• Keep medication secure—high abuse potential

Other Anxiolytic & Hypnotic Agents

First-Generation Antihistamines

• diphenhydramine (Benadryl)

• promethazine
  Therapeutic uses: short-term insomnia, motion sickness, N/V.
  Adverse: anticholinergic effects (dry mouth, urinary retention), dizziness, next-day drowsiness.

Non-benzodiazepine Hypnotics (“Z-drugs”)

• eszopiclone (Lunesta) – chronic insomnia
  • Side effects: unpleasant taste, memory loss, complex sleep behaviors ("sleep-driving"), loss of coordination.

• zolpidem (Ambien) – short-term insomnia
  • Side effects: same “sleep-driving,” bizarre nighttime behaviors, next-day psychomotor impairment.

Buspirone (Buspar)

• Mechanism: partial 5-HT$_{1A}$ receptor agonist; minimal GABA activity.

• Benefits: anxiolytic without significant CNS depression, sedation, or addiction; no interaction with alcohol.

• Drawbacks: delayed onset (1–4 weeks); not useful for acute anxiety/panic.

Patient Teaching for ALL Other Agents

• Do not drive until individual response known (complete prohibition for “Z-drugs” at bedtime).

• NO alcohol or additional CNS depressants.

• Report complex sleep behaviors immediately.

• If insomnia persists > $7$–$10$ days, consult prescriber for further evaluation.

Comparative Clinical Pearls

• Benzos vs barbiturates: both enhance GABA; benzos ↑ frequency, barbs ↑ duration of chloride channel opening; barbs more dangerous (no ceiling effect).

• Flumazenil reverses benzos but not barbiturates or Z-drugs → know specific antidotes.

• Buspirone ideal for daytime anxiety when alertness required; zero abuse potential.

• Antihistamines useful when insomnia is related to allergy symptoms; watch for anticholinergic burden in elderly.

Ethical & Practical Implications

• High abuse & diversion risk mandates secure storage, careful prescription counts, and patient contracts.

• Consider non-pharmacologic anxiety/sleep interventions first (CBT, sleep hygiene, relaxation).

• Polypharmacy vigilance: avoid layering multiple CNS depressants; perform medication reconciliation.

• Educate patients on legal ramifications of “driving under the influence” of prescribed sedatives.

Summary Checklist (Quick Review)

• Assess: baseline anxiety level, sleep patterns, VS, substance use history, pregnancy status, hepatic/renal labs.

• Administer: PO forms with food if GI upset; IV slowly; avoid IM when painful alternatives exist.

• Monitor: BP $\downarrow$, RR $\downarrow$, LOC, signs of paradoxical excitement or withdrawal.

• Prevent injury: bed alarms, assist ambulation, no driving.

• Discontinue: taper gradually; provide written schedule.

• Educate: avoid alcohol/opioids, high addiction potential, legality of impaired driving, store securely, follow-up if insomnia/anxiety persists.

End of notes – use as a comprehensive replacement for original lecture slides.