Cns depressants

Central Nervous System Central Nervous System DepressantsDepressants

CNS Depressants CNS Depressants

SedativesSedatives

• Drugs that have an inhibitory effect on the Drugs that have an inhibitory effect on the CNS to the degree that they reduce:CNS to the degree that they reduce:

– NervousnessNervousness

– ExcitabilityExcitability

– IrritabilityIrritability

– without causing sleepwithout causing sleep

CNS Depressants CNS Depressants

HypnoticsHypnotics

• Calm or soothe the CNS to the point that they Calm or soothe the CNS to the point that they cause sleepcause sleep

CNS DepressantsCNS Depressants

Sedative-Hypnotics—dose dependent:Sedative-Hypnotics—dose dependent:

• At low doses, calm or soothe the CNS At low doses, calm or soothe the CNS without inducing sleepwithout inducing sleep

• At high doses, calm or soothe the CNSAt high doses, calm or soothe the CNS

• to the point of causing sleepto the point of causing sleep

Sedative-Hypnotics: BarbituratesSedative-Hypnotics: Barbiturates

• First introduced in 1903, standard agents First introduced in 1903, standard agents for insomnia and sedationfor insomnia and sedation

• Habit-formingHabit-forming

• Only a handful commonly used today due Only a handful commonly used today due in part to the safety and efficacy of: in part to the safety and efficacy of: BENZODIAZEPINESBENZODIAZEPINES


Four categories:Four categories:

• UltrashortUltrashort

– mephobexital, thiamylal, thiopentalmephobexital, thiamylal, thiopental

• ShortShort

– pentobarbital, secobarbitalpentobarbital, secobarbital

• IntermediateIntermediate

– aprobarbital, butabarbitalaprobarbital, butabarbital

• LongLong

– phenobarbitalphenobarbital


Barbiturates have a very narrow therapeutic index.Barbiturates have a very narrow therapeutic index.

Therapeutic IndexTherapeutic Index

• Dosage range within which the drug is effective Dosage range within which the drug is effective but above which is rapidly toxic.but above which is rapidly toxic.


Mechanism of ActionMechanism of Action

• Site of action:Site of action:

– Brain stem (reticular formation)Brain stem (reticular formation)

– Cerebral cortexCerebral cortex

• By inhibiting GABA, nerve impulses traveling in By inhibiting GABA, nerve impulses traveling in the cerebral cortex are also inhibited.the cerebral cortex are also inhibited.


Drug EffectsDrug Effects

• Low doses:Low doses: Sedative effectsSedative effects

• High doses:High doses: Hypnotic effectsHypnotic effects(also lowers respiratory rate)(also lowers respiratory rate)

Notorious enzyme inducersNotorious enzyme inducers


Therapeutic UsesTherapeutic Uses

• HypnoticsHypnotics

• SedativesSedatives

• AnticonvulsantsAnticonvulsants

• Surgical proceduresSurgical procedures


Side EffectsSide Effects

Body SystemBody System EffectsEffects

CNSCNS Drowsiness, lethargy, vertigoDrowsiness, lethargy, vertigomental depression, comamental depression, coma

RespiratoryRespiratory Respiratory depression, apnea, Respiratory depression, apnea, bronchospasms, coughbronchospasms, cough



Body SystemBody System EffectsEffects

GIGI Nausea, vomiting, diarrheaNausea, vomiting, diarrhea

OtherOther Agranulocytosis, Agranulocytosis, vasodilation, vasodilation,

hypotension, hypotension, Stevens-Johnson Stevens-Johnson syndromesyndrome


ToxicologyToxicology

• Overdose frequently leads to respiratory depression, Overdose frequently leads to respiratory depression, and subsequently, respiratory arrest.and subsequently, respiratory arrest.

• Can be therapeutic:Can be therapeutic:

– Anesthesia inductionAnesthesia induction

– Uncontrollable seizures: “phenobarbital coma”Uncontrollable seizures: “phenobarbital coma”


Drug InteractionsDrug Interactions

• Additive effects:Additive effects:

– ETOH, antihistamines, benzodiazepines, ETOH, antihistamines, benzodiazepines, narcotics, tranquilizersnarcotics, tranquilizers

• Inhibited metabolism:Inhibited metabolism:

– MAOIs will prolong effects of barbituratesMAOIs will prolong effects of barbiturates

• Increased metabolism:Increased metabolism:

– Reduces anticoagulant response, leading to Reduces anticoagulant response, leading to possible clot formationpossible clot formation

CNS Depressants: BenzodiazepinesCNS Depressants: Benzodiazepines

Most frequently prescribed sedative-hypnoticsMost frequently prescribed sedative-hypnotics

• Most commonly prescribed drug classesMost commonly prescribed drug classes

• Favorable side effectsFavorable side effects

• EfficacyEfficacy

• SafetySafety


Classified as either:Classified as either:

• Sedative-hypnotic or AnxiolyticSedative-hypnotic or Anxiolytic

(Medication that relieves anxiety)(Medication that relieves anxiety)


Sedative-Hypnotic TypeSedative-Hypnotic Type

• Long-Acting:Long-Acting:

– flurazepam (Dalmane), quazepam (Doral)flurazepam (Dalmane), quazepam (Doral)

• Short-Acting:Short-Acting:

– estazolam (Prosom), temazepam (Restoril),estazolam (Prosom), temazepam (Restoril),

– triazolam (Halcion)triazolam (Halcion)


Anxiolytic TypeAnxiolytic Type

• alprazolam (Xanax)alprazolam (Xanax)

• chloridiazepoxide (Librium)chloridiazepoxide (Librium)

• diazepam (Valium)diazepam (Valium)

• lorazepam (Ativan)lorazepam (Ativan)

• midazolam (Versed)midazolam (Versed)

zolpidem (Ambien) and zaleplon (Sonata)zolpidem (Ambien) and zaleplon (Sonata)

(nonbenzodiazepine hypnotic agents, share characteristics)(nonbenzodiazepine hypnotic agents, share characteristics)


Mechanism of ActionMechanism of Action

• Depress CNS activityDepress CNS activity

• Affect hypothalamic, thalamic, and limbic Affect hypothalamic, thalamic, and limbic systems of the brainsystems of the brain

• Benzodiazepine receptorsBenzodiazepine receptors


Drug EffectsDrug Effects

• Calming effect on the CNSCalming effect on the CNS

• Useful in controlling agitation and anxietyUseful in controlling agitation and anxiety


Therapeutic UsesTherapeutic Uses

• SedationSedation

• Sleep inductionSleep induction

• Skeletal muscle relaxationSkeletal muscle relaxation

• Anxiety reliefAnxiety relief

• Treatment of alcohol withdrawalTreatment of alcohol withdrawal

• AgitationAgitation

• DepressionDepression

• EpilepsyEpilepsy

• Balanced anesthesiaBalanced anesthesia



• Mild and infrequentMild and infrequent

HeadacheHeadache DrowsinessDrowsinessDizzinessDizziness VertigoVertigoLethargyLethargyParadoxical excitement (nervousness) Paradoxical excitement (nervousness) “Hangover effect”“Hangover effect”

CNS Depressants: CNS Depressants: Nursing ImplicationsNursing Implications

• Before beginning therapy, perform a Before beginning therapy, perform a thorough history regarding allergies, use thorough history regarding allergies, use of other medications,health history, and of other medications,health history, and medical history.medical history.

• Obtain baseline vital signs and I & O, Obtain baseline vital signs and I & O, including supine and erect BPs.including supine and erect BPs.

• Assess for potential disorders or conditions Assess for potential disorders or conditions that may be contraindications, and for that may be contraindications, and for potential drug interactions.potential drug interactions.


• Give 15 to 30 minutes before bedtime for Give 15 to 30 minutes before bedtime for maximum effectiveness in inducing sleep.maximum effectiveness in inducing sleep.

• Most benzodiazepines (except flurazepam) Most benzodiazepines (except flurazepam) cause REM rebound and a tired feeling the cause REM rebound and a tired feeling the next day; use with caution in the elderly.next day; use with caution in the elderly.

• Patients should be instructed to avoid Patients should be instructed to avoid alcohol and other CNS depressants.alcohol and other CNS depressants.


• Check with physician before taking any other Check with physician before taking any other medications, including OTC medications.medications, including OTC medications.

• It may take 2 to 3 weeks to notice improved It may take 2 to 3 weeks to notice improved sleep when taking barbiturates.sleep when taking barbiturates.

• Abruptly stopping these medications, Abruptly stopping these medications, especially barbiturates, may cause rebound especially barbiturates, may cause rebound insomnia.insomnia.


• Safety is importantSafety is important

– Keep side rails upKeep side rails up

– Do not permit smokingDo not permit smoking

– Assist patient with ambulation Assist patient with ambulation (especially the elderly)(especially the elderly)

– Keep call light within reachKeep call light within reach

• Monitor for side effectsMonitor for side effects


• Monitor for therapeutic effectsMonitor for therapeutic effects

– Increased ability to sleep at nightIncreased ability to sleep at night

– Fewer awakeningsFewer awakenings

– Shorter sleep induction timeShorter sleep induction time

– Few side effects, such as hangover effectsFew side effects, such as hangover effects

– Improved sense of well-being because of Improved sense of well-being because of improved sleepimproved sleep

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Cns depressants