Module 3 Central Nervous System Depressants Flashcards Preview

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Flashcards in Module 3 Central Nervous System Depressants Deck (29):
1

CNS Depressants

Sedatives
 Drugs that have an inhibitory effect on the
CNS to the degree that they reduce:
 Nervousness
 Excitability
 Irritability without causing sleep
Hypnotics
Cause sleep
sedative can become a hypnotic it is given in large enough dose
Sedative-hypnotics—dose dependent
At low doses, calm the CNS without inducing sleep
At high doses, calm the to the point of causing sleep
Barbiturates
Benzodiazepines

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Sleep

Normal sleep is cyclic and repetitive
A sleeping person is unaware of sensory stimuli
within the immediate environment
 Rapid eye movement (REM) sleep
 Non–rapid eye movement (non-REM) sleep
 Sleep stages
 REM rebound

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CNS Depressants:
Benzodiazepines

A commonly prescribed drug class Favorable drug effect profiles, efficacy, and
safety

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Benzodiazepines:
Classification

Classified as either:
sedative-hypnotic
Anxiolytic (medication that relieves anxiety)

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Benzodiazepines:
Sedative-Hypnotic Types

Long-acting
estazolam (Prosom), flurazepam (Dalmane),
lorazepam (Ativan)
Short-acting
temazepam (Restoril), alprazolam (Xanax),
triazolam (Halcion

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CNS Depressants:
Nonbenzodiazepine Hypnotics

Share many characteristics of benzodiazepines
Used to treat insomnia
Examples: zaleplon (Sonata), zolpidem (Ambien),
eszopiclone (Lunesta), and ramelteon (Rozerem)
Eszopiclone and extended-release zolpidem (Ambien CR) approved for long-term therapy

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CNS Depressants:
Nonbenzodiazepine Hypnotics

Ramelteon (Rozerem)
 Does not cause CNS depression
 No potential for abuse
 No withdrawal signs and symptoms

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Benzodiazepines:
Mechanism of Action

Depress CNS activity
Affect hypothalamic, thalamic, and limbic
systems of the brain
Benzodiazepine receptors
Do not suppress REM sleep as much as barbiturates do
Do not increase metabolism of other drugs

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Benzodiazepines:
Drug Effects

Calming effect on the CNS
 Useful in controlling agitation and anxiety
 Reduce excessive sensory stimulation,
inducing sleep
 Induce skeletal muscle relaxation

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Benzodiazepines:
Indications

Sedation
 Sleep induction
 Skeletal muscle relaxation
 Anxiety relief
 Treatment of alcohol withdrawal
Agitation Depression Epilepsy
 Balanced anesthesia
 Moderate/conscious sedation

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Benzodiazepines: Adverse
Effects

Mild and infrequent
 Headache
 Drowsiness
 Dizziness
 Vertigo
 Lethargy
 Fall hazard for frail elderly persons
 “Hangover” effect/daytime sleepiness

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Benzodiazepines:
Toxicity and Overdose

Somnolence
 Confusion
 Coma
 Diminished reflexes
 Do not cause hypotension and respiratory
depression unless taken with other CNS
depressants
 Treatment symptomatic and supportive
 Flumazenil as an antidote

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Herbal Products: Kava

Used to relieve anxiety, stress, and restlessness, and to promote sleep
 May cause temporary yellow skin discoloration(extended, continued intake)
 May cause visual disturbances
 Potential interactions with alcohol, barbiturates, and psychoactive drugs
 Contraindicated in liver disease, alcoholism, other conditions
Patient should not operate heavy machinery during

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Herbal Products: Valerian

Used to relieve anxiety, restlessness, and sleep
disorders
May cause CNS depression, hepatotoxicity, nausea,
vomiting anorexia restlessness insomnia
vomiting, anorexia, restlessness,  Many interactions, including with CNS depressants, MAOIs, phenytoin, warfarin, alcohol
Contraindicated in cardiac and liver disease Patient should not operate heavy machinery duringuse

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Sedative-Hypnotics: Barbiturates

First introduced in 1903; were the standard
drugs for insomnia and sedatio
 Habit forming; low therapeutic index
 Only a handful commonly used today due in
part to the safety and efficacy of
benzodiazepines

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Therapeutic Index

Ratio between the toxic and therapeutic
concentrations of a drug
 Barbiturates have a very low therapeutic
index

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Barbiturates:
Mechanism of Action

Site of action
 Brainstem (reticular formation)
 By facilitating GABA, nerve impulses traveling in the cerebral cortex are inhibited

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Barbiturates: Drug Effects

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

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Barbiturates: Indications

Hypnotics
 Sedatives
 Anticonvulsants
 Anesthesia for surgical procedures

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Barbiturates: Four Categories

Ultra short-acting
 Anesthesia for short surgical procedures
 Short-acting
Sedation/sleep induction and control of convulsive
conditions
 Intermediate-acting
 Sedation/sleep induction and control of convulsive
conditions
 Long-acting
 Sleep induction, epileptic seizure prophylaxis

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Barbiturates: Four Categories
(cont’d)

Ultrashort
 methohexital, thiopental
Short
 pentobarbital, secobarbital
Intermediate
 butabarbital
Long
 phenobarbital, mephobarbital

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Barbiturates: Onset and Duration

Ultrashort - Onset IV less than 15 mins
Duration IV less than 2 hrs
Short- Onset PO: 15 to 20 mins
Duration PO: 2 to 4 hrs
Intermediate-Onset PO: 20 to 30 mins
Duration PO: 2 to 4 hrs
Long- Onset PO: 30 to 60 mins
Duration PO: 6 to 8 hrs

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Barbiturates: Adverse Effects

Body System Adverse Effects
CNS Drowsiness, lethargy,vertigo mental depression vertigo, Respiratory Respiratory depression,apnea, bronchospasms,cough
Body System Adverse Effects
GI Nausea, vomiting, diarrhea,constipation
Other Agranulocytosis,
hypotension, Stevens-
Johnson syndrome
Reduced REM sleep, resulting in:
 Agitation Inability to deal with normal stress

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Barbiturates:
Toxicity and Overdose

Overdose frequently leads to respiratory depression,
and subsequent respiratory arrest
Overdose produces CNS depression (sleep to coma and death)
 Can be therapeutic
 Anesthesia induction
 Uncontrollable seizures: “phenobarbital coma”
Treatment of overdose
 Symptomatic and supportive
 Maintain adequate airway
 Assisted ventilation/oxygen therapy
 Fluids
 Pressor support
 Activated charcoal

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Barbiturates:
Drug Interactions

Additive effects
 ETOH, antihistamines, benzodiazepines, opioids
Metabolism inhibited by other drugs
MAOIs will prolong effects of barbiturates
 Increased metabolism of other drugs
 Reduces anticoagulant response, leading to possible clot formation

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Muscle Relaxants

Act to relieve pain associated with skeletal
muscle spasms
 Majority are central-acting
 CNS is the site of action
Similar in structure and action to other CNS
depressants
 Direct-acting
 Act directly on skeletal muscle
 Closely resemble GABA

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Muscle Relaxants: Indications

Relief of painful musculoskeletal conditions
 Muscle spasms
 Management of spasticity of severe chronic disorders, eg. multiple sclerosis, cerebral palsy
Work best when used along with physical therapy
dantrolene (Dantrium)
 Malignant hyperthermia

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Muscle Relaxants: Adverse
Effects

Extension of effects on CNS and skeletal
muscles
 Euphoria
 Lightheadedness
 Dizziness
 Drowsiness
 Fatigue
 Muscle weakness

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Common Muscle Relaxants

baclofen (Lioresal)
 cyclobenzaprine ( Flexeril)
 dantrolene (Dantrium)
 metaxalone (Skelaxin)
 tizanidine (Zanaflex)