Central Nervous System Depressants & Muscle Relaxants – Key Vocabulary

Vocabulary flashcards summarizing key terms, drug names, mechanisms, indications, contraindications, adverse effects, interactions, and nursing considerations related to CNS depressants and muscle relaxants.

Sedatives

Drugs that inhibit the CNS enough to reduce nervousness, excitability, and irritability.

Hypnotics

Agents that induce sleep; stronger CNS depressant effect than sedatives.

Dose-dependent sedative-hypnotics

Low doses calm without sleep; high doses calm to the point of sleep induction.

Major classes of CNS depressants

Barbiturates, benzodiazepines, and miscellaneous drugs.

REM (Rapid Eye Movement) sleep

Stage of sleep with rapid eye movements; dreaming occurs here.

Non-REM sleep

All stages of normal sleep other than REM; includes light and deep sleep phases.

REM interference

Reduction of REM sleep caused by some drugs, leading to sleep pattern disruption.

REM rebound

Excessive REM after drug withdrawal, often with vivid dreams.

Benzodiazepines

Formerly most-used sedative-hypnotics; favorably safe when used correctly.

Anxiolytic

Medication, often a benzodiazepine, used to relieve anxiety.

Nonbenzodiazepine hypnotic

Sleep aid that acts like a benzodiazepine but is chemically distinct.

Ramelteon (Rozerem)

Melatonin-receptor agonist for sleep-onset insomnia; not a controlled substance.

Suvorexant (Belsomra)

First orexin receptor antagonist for insomnia; 12-h half-life with daytime somnolence risk.

Tasimelteon (Hetlioz)

Melatonin-receptor agonist for blind patients with sleep-wake cycle disturbance.

Benzodiazepine mechanism

Enhance GABA at specific receptors in hypothalamus, thalamus, limbic system.

Gamma-aminobutyric acid (GABA)

Primary inhibitory neurotransmitter in the CNS; target of many depressants.

Benzodiazepine therapeutic effects

Calming, anxiolysis, sleep induction, skeletal muscle relaxation.

Sedation indication

Use of benzodiazepines to calm patients without full sleep.

Acute seizure treatment

Short-term control of seizures with benzodiazepines such as diazepam.

Benzodiazepine contraindication

Includes drug allergy, pregnancy, and narrow-angle glaucoma.

Common benzodiazepine adverse effects

Headache, drowsiness, dizziness, cognitive impairment, hangover effect.

Hangover effect

Next-day drowsiness after benzodiazepine-induced sleep.

Flumazenil

Specific antidote for benzodiazepine overdose.

Grapefruit juice interaction

Raises benzodiazepine levels by inhibiting metabolism; avoid concurrent use.

Kava

Herbal anxiolytic that may discolor skin and interacts with CNS depressants.

Valerian

Herbal product for insomnia; adverse effects include CNS depression and hepatotoxicity.

Diazepam (Valium)

First benzodiazepine; used for anxiety, seizures, muscle spasm, procedural sedation.

Midazolam (Versed)

Injectable benzodiazepine for preop and conscious sedation; causes amnesia.

Temazepam (Restoril)

Intermediate-acting benzodiazepine hypnotic taken ~1 h before bed.

Eszopiclone (Lunesta)

First long-term nonbenzodiazepine hypnotic; provides a full 8 h sleep.

Zolpidem (Ambien)

Short-acting nonbenzodiazepine; CR form has dual reservoirs; risk of somnambulation.

Ambien CR

Extended-release zolpidem with two layers for sustained sleep maintenance.

Orexin receptor antagonist

Drug class blocking wake-promoting neuropeptides (e.g., suvorexant).

Barbiturates

Older hypnotic class with low therapeutic index and high habit-forming potential.

Barbiturate mechanism

Potentiate GABA to inhibit cortical impulses via brainstem reticular formation.

Low therapeutic index

Narrow range between effective and toxic doses (characteristic of barbiturates).

Ultrashort-acting barbiturate use

Induction of anesthesia, short procedures, intracranial pressure reduction.

Long-acting barbiturate use

Prophylaxis of epileptic seizures (e.g., phenobarbital).

Phenobarbital

Prototype long-acting barbiturate for seizure prevention and neonatal jaundice.

Pentobarbital (Nembutal)

Long-acting barbiturate once used for anxiety; now limited to sedation & seizure control.

Reduced REM with barbiturates

Leads to agitation and restlessness during withdrawal.

Barbiturate toxicity hallmark

Respiratory depression progressing to arrest.

Overdose management (barbiturate)

Airway, oxygen, fluids, pressors, urine alkalinization; supportive care.

Barbiturate enzyme induction

Accelerates metabolism of other drugs, reducing effects of anticoagulants, etc.

OTC hypnotics

Non-prescription sleep aids containing antihistamines (e.g., diphenhydramine).

Doxylamine

OTC antihistamine sedative found in Unisom.

Diphenhydramine

Antihistamine in Sominex & Tylenol-PM; causes CNS depression.

Muscle relaxants

Drugs that relieve skeletal muscle spasms and spasticity.

Centrally acting muscle relaxant

Acts within CNS to reduce muscle tone (e.g., cyclobenzaprine).

Direct-acting muscle relaxant

Acts on skeletal muscle itself (e.g., dantrolene).

Malignant hyperthermia

Life-threatening reaction treated IV with dantrolene.

Baclofen (Lioresal)

Centrally acting relaxant; available as oral or intrathecal pump for chronic spasticity.

Cyclobenzaprine (Flexeril)

Common centrally acting relaxant; causes marked sedation.

Dantrolene (Dantrium)

Direct-acting relaxant and antidote for malignant hyperthermia.

Tizanidine (Zanaflex)

Alpha-2 agonist muscle relaxant for spasticity.

Carisoprodol (Soma)

Centrally acting relaxant; may cause euphoria and abuse potential.

Chlorzoxazone (Paraflex)

Centrally acting skeletal muscle relaxant.

Methocarbamol (Robaxin)

Muscle relaxant often producing CNS depression and urine discoloration.

Muscle relaxant adverse effects

Euphoria, dizziness, drowsiness, fatigue, muscle weakness.

Muscle relaxant overdose care

Supportive measures, airway, ECG, fluids; no specific antidote.

Hypnotic timing

Administer 30–60 min before bedtime for optimal sleep induction.

Alcohol avoidance

Essential for patients on CNS depressants to prevent respiratory depression.

Rebound insomnia

Temporary sleeplessness after stopping a long-term hypnotic regimen.

Older-adult caution

Use lowest benzodiazepine dose; risk of falls and REM rebound.

Bed safety measures

Side rails up, bed alarms, assist with ambulation when using CNS depressants.

Somnambulation

Sleep-walking episodes reported with zolpidem use.

Nonbenzodiazepine daytime alertness

Agents like zolpidem have less next-day drowsiness than benzodiazepines.

Ramelteon scheduling

Not classified as a controlled substance due to lack of abuse potential.

Suvorexant half-life

Approximately 12 hours, contributing to possible daytime drowsiness.

Narrow-angle glaucoma

Contraindication for benzodiazepine use.

Pregnancy and benzodiazepines

Avoid due to potential fetal harm; listed as contraindication.

Fall hazard

Older adults on benzodiazepines or barbiturates are at increased risk.

Selective orexin receptor antagonist

Drug that blocks orexin to induce sleep (suvorexant).

Flumazenil classification

Competitive benzodiazepine receptor antagonist used for reversal.