Download Sedatives

Chapter 12
Central Nervous System Depressants
and Muscle Relaxants
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
CNS Depressants
Sedatives
 Drugs that have an inhibitory effect on the
CNS to the degree that they reduce:



Nervousness
Excitability
Irritability
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CNS Depressants (cont’d)
Hypnotics
 Cause sleep
 Much more potent effect on CNS than sedatives
 A sedative can become a hypnotic if it is given in
large enough doses
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CNS Depressants (cont’d)




Sedative-hypnotics—dose dependent
At low doses, calm the CNS without inducing
sleep
At high doses, calm the CNS to the point of
causing sleep
Classified into three main groups:



Barbiturates
Benzodiazepines
Miscellaneous drugs
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Sleep



Normal sleep is cyclic and repetitive
A sleeping person is unaware of sensory stimuli
within the immediate environment
Sleep architecture




Rapid eye movement (REM) sleep
Non-REM sleep
REM interference
REM rebound
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CNS Depressants:
Benzodiazepines



Formerly the most commonly prescribed
sedative-hypnotic drugs
Nonbenzodiazepines currently more frequently
prescribed
Favorable drug effect profiles, efficacy, and
safety
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Benzodiazepines
Classified as either:


Sedative-hypnotic
Anxiolytic (medication that relieves anxiety)
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Benzodiazepines:
Sedative-Hypnotic Types

Long-acting


Intermediate-acting


diazepam (Valium), clonazepam (Klonopin)
alprazolam (Xanax), lorazepam (Ativan), temazepam
(Restoril)
Short-acting

midazolam (Versed), triazolam (Halcion)
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Benzodiazepines: Mechanism of
Action



Depress CNS activity
Affect hypothalamic, thalamic, and limbic
systems of the brain
Benzodiazepine receptors



Gamma-aminobutyric acid (GABA)
Do not suppress rapid eye movement (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
Anxiety-related depression
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Benzodiazepines: Indications
(cont’d)





Treatment of acute seizure disorders
Treatment of alcohol withdrawal
Agitation relief
Balanced anesthesia
Moderate/conscious sedation
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Benzodiazepines:
Adverse Effects
Mild and infrequent
 Headache
 Drowsiness
 Dizziness
 Cognitive impairment
 Vertigo
 Lethargy
 Fall hazard for elderly persons
 “Hangover” effect/daytime sleepiness
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Classroom Response Question
When providing education to the patient on the use of a
benzodiazepine medication, the nurse will include which
information?
A. These medications have little effect on the normal sleep
cycle.
B. Using this medication may cause drowsiness the next
day.
C. It is safe to drive while taking this medication.
D. These drugs are safe to use with alcohol.
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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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Benzodiazepines:
Interactions




Azole antifungals, verapamil, diltiazem, protease
inhibitors, macrolide antibiotics, grapefruit juice
CNS depressants (alcohol, opioids)
olanzapine
rifampin
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CNS Depressants:
Nonbenzodiazepine Hypnotics




Share many characteristics of benzodiazepines
Used to treat insomnia
Examples: zaleplon (Sonata), zolpidem
(Ambien), eszoplicone (Lunesta), and ramelteon
(Rozerem)
Eszoplicone and extended-release zolpidem
(Ambien CR) approved for long-term therapy
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CNS Depressants: Nonbenzodiazepine
Hypnotics (cont’d)

Ramelteon (Rozerem)



Does not cause CNS depression
No potential for abuse
No withdrawal signs and symptoms
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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) and visual disturbances
Potential interactions with alcohol, barbiturates, and
psychoactive drugs
Contraindicated in liver disease, alcoholism, other
conditions
Patient should not operate heavy machinery during use
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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
Many interactions, including with CNS depressants,
MAOIs, phenytoin, warfarin, alcohol
Contraindicated in cardiac and liver disease
Patient should not operate heavy machinery during use
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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
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Barbiturates:
Mechanism of Action

Site of action


Brainstem (reticular formation)
By potentiating the action of 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 metabolism or
breakdown of many drugs
Result in shortened duration of action
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Barbiturates: Indications



Sedatives
Anticonvulsants
Anesthesia for surgical procedures
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Barbiturates: Four Categories

Ultrashort-acting


Short-acting


Sedation and control of convulsive conditions
Intermediate-acting


Anesthesia for short surgical procedures, other uses
Sedation and control of convulsive conditions
Long-acting

Sleep induction, epileptic seizure prophylaxis
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Barbiturates: Adverse Effects
Body System
Adverse Effects
Cardiovascular
Vasodilation, hypotension
CNS
Drowsiness, lethargy, vertigo
Respiratory
Respiratory depression, cough
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Barbiturates: Adverse Effects
(cont’d)
Body System
GI
Adverse Effects
Nausea, vomiting, diarrhea,
constipation
Hematologic
Agranulocytosis,
thrombocytopenia
Other
Hypersensitivity reactions,
Stevens-Johnson syndrome
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Barbiturates: Adverse Effects
(cont’d)

Reduced REM sleep, resulting in:


Agitation
Inability to deal with normal stress
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Classroom Response Question
An elderly patient taking multiple medications has a
barbiturate added to his medication regimen. When
administering a barbiturate to an elderly patient, the nurse
should expect
A. a decrease in dosages of the other medications.
B. the patient will experience increased amounts of REM
sleep.
C. to administer half of the usual dose of the barbiturate.
D. total relief of anxiety.
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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”
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Barbiturates:
Toxicity and Overdose (cont’d)

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


Inhibited metabolism


Alcohol, antihistamines, benzodiazepines, opioids,
tranquilizers
MAOIs will prolong effects of barbiturates
Increased metabolism

Reduces anticoagulant response, leading to possible
clot formation
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Common Barbiturates


pentobarbital (Nembutol)
phenobarbital
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Classroom Response Question
Barbiturates have a low therapeutic index. This
means
A.
B.
C.
D.
low doses are not therapeutic.
the toxic range is narrow.
they are habit forming.
the effective, safe dosage range is narrow.
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Muscle Relaxants


Act to relieve pain associated with skeletal
muscle spasms
Majority are centrally 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
(multiple sclerosis, cerebral palsy)
Work best when used along with physical
therapy
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Muscle Relaxants:
Adverse Effects

Extension of effects on CNS and skeletal
muscles

Euphoria
 Lightheadedness
 Dizziness
 Drowsiness
 Fatigue
 Muscle weakness, others
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Common Muscle Relaxants

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baclofen (Lioresal)
cyclobenzaprine (Flexeril)
dantrolene (Dantrium)
metaxalone (Skelaxin)
tizanidine (Zanaflex)
carisoprodol (Soma)
chlorzoxazone (Paraflex)
methocarbamol (Robaxin)
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Classroom Response Question
Which statement regarding muscle relaxants does the
nurse identify as being accurate?
A. Baclofen (Lioresal) is available as an injectable form for
use with an implantable pump device.
B. Cyclobenzaprine (Flexeril) produces little sedation.
C. Patients taking muscle relaxants are at high risk to
develop hypertension.
D. Patients taking muscle relaxants should be told to stop
taking the medication if they feel sleepy.
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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
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Nursing Implications



Give hypnotics 30 to 60 minutes before bedtime
for maximum effectiveness in inducing sleep
(depends on drug’s onset)
Most benzodiazepines cause REM rebound and
a tired feeling the next day; use with caution in
the elderly
Instruct patients to avoid alcohol and other CNS
depressants
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Nursing Implications (cont’d)


Check with prescriber 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
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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
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Nursing Implications (cont’d)

Monitor for therapeutic effects

Increased ability to sleep at night
 Fewer awakenings
 Shorter sleep-induction time
 Few adverse effects, such as “hangover” effects
 Improved sense of well-being because of improved
sleep
For muscle relaxants:
 Decreased spasticity, decreased rigidity
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