Transcript Chapter 13 - The Red Zone

CHAPTER 13
Central Nervous System Depressants
and Muscle Relaxants
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CNS Depressants
Sedatives
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Drugs that have an inhibitory effect on the
CNS to the degree that they reduce:
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Nervousness
Excitability
Irritability without causing sleep
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CNS Depressants (cont’d)
Hypnotics
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Cause sleep
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
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At low doses, calm the CNS without inducing sleep
At high doses, calm the CNS to the point of causing
sleep
 Barbiturates
 Benzodiazepines
 Others
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Sleep
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Normal sleep is cyclic and repetitive
A sleeping person is unaware of sensory
stimuli within the immediate environment
Rapid eye movement (REM) sleep
Non-REM sleep
Sleep stages
REM rebound
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CNS Depressants:
Benzodiazepines
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
A commonly prescribed drug class
Favorable drug effect profiles, efficacy, and
safety
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Benzodiazepines
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Classified as either:
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Sedative-hypnotic
Anxiolytic (medication that relieves anxiety)
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Benzodiazepines:
Sedative-Hypnotic Types
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Long-acting
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estazolam (Prosom), flurazepam (Dalmane),
lorazepam (Ativan), others
Short-acting
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temazepam (Restoril), alprazolam (Xanax),
triazolam (Halcion), others
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CNS Depressants:
Nonbenzodiazepine Hypnotics
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Share many characteristics of
benzodiazepines
Used to treat insomnia
Examples: zalepion (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
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Ramelteon (Rozerem)
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Does not cause CNS depression
 No potential for abuse
 No withdrawal signs and symptoms
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Benzodiazepines: Mechanism of
Action
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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
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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
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Sedation
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Sleep induction
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Skeletal muscle relaxation
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Anxiety relief
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Treatment of alcohol withdrawal
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Benzodiazepines: Indications
(cont’d)
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Agitation
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Depression
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Epilepsy
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Balanced anesthesia
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Moderate/conscious sedation
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Benzodiazepines:
Adverse Effects
Mild and infrequent
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Headache
Drowsiness
Dizziness
Vertigo
Lethargy
Fall hazard for elderly persons
“Hangover” effect/daytime sleepiness
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Benzodiazepines:
Toxicity and Overdose
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Somnolence
Confusion
Coma
Diminished reflexes
Do not cause hypotension and respiratory
depression unless taken with other CNS
depressants
Treatment symptomatic and supportive
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Flumazenil as an antidote
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Benzodiazepines:
Interactions
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Other CNS depressants (alcohol, opioids)
Cimetidine
MAOIs
Herbal products: kava and valerian
Grapefruit juice alters drug absorption
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Herbal Products: Kava
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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
use
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Herbal Products: Valerian
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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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Sedative-Hypnotics: Barbiturates
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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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Therapeutic Index
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Dosage range within which a drug is effective
but above which it is rapidly toxic
Barbiturates have a very narrow therapeutic
index
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Barbiturates:
Mechanism of Action
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Site of action
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Brainstem (reticular formation)
By inhibiting GABA, nerve impulses traveling
in the cerebral cortex are also inhibited
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Barbiturates: Drug Effects
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Low doses: sedative effects
High doses: hypnotic effects (also lower
respiratory rate)
Notorious enzyme inducers
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Stimulate liver enzymes that cause metabolism or
breakdown of many drugs
 Result in shortened duration of action
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Barbiturates: Indications
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Hypnotics
Sedatives
Anticonvulsants
Anesthesia for surgical procedures
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Barbiturates: Four Categories
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Ultra short-acting
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Short-acting
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Sedation/sleep induction and control of
convulsive conditions
Intermediate-acting
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Anesthesia for short surgical procedures, other
uses
Sedation/sleep induction and control of
convulsive conditions
Long-acting
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Sleep induction, epileptic seizure prophylaxis
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Barbiturates: Four Categories
(cont’d)
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Ultra short-acting
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Short-acting
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Pentobarbital, secobarbital
Intermediate-acting
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Mephohexital, thiopental
Butabarbital
Long-acting
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Phenobarbital, mephobarbital
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Barbiturates: Adverse Effects
Body System
CNS
Respiratory
Adverse Effects
Drowsiness, lethargy,
vertigo, mental depression,
others
Respiratory depression,
apnea, bronchospasms,
cough
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Barbiturates: Adverse Effects
(cont’d)
Body System
GI
Adverse Effects
Nausea, vomiting, diarrhea,
constipation
Other
Agranulocytosis,
hypotension, StevensJohnson syndrome, others
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Barbiturates: Adverse Effects
(cont’d)
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Reduced REM sleep, resulting in:
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Agitation
Inability to deal with normal stress
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Barbiturates:
Toxicity and Overdose
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Overdose frequently leads to respiratory
depression and subsequent respiratory arrest
Overdose produces CNS depression (sleep
to coma and death)
Can be therapeutic
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Anesthesia induction
Uncontrollable seizures: “phenobarbital coma”
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Barbiturates:
Toxicity and Overdose
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Treatment of overdose
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Symptomatic and supportive
 Maintain adequate airway
 Assisted ventilation/oxygen therapy
 Fluids
 Pressor support
 Activated charcoal
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Barbiturates: Drug Interactions
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Additive effects
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Inhibited metabolism
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Alcohol, antihistamines, benzodiazepines,
opioids, tranquilizers
MAOIs will prolong effects of barbiturates
Increased metabolism
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Reduces anticoagulant response, leading to
possible clot formation
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Common Barbiturates
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butabarbital (Butisol)
pentobarbital (Nembutol)
phenobarbital (Luminal)
secobarbital (Seconal)
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Muscle Relaxants
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Act to relieve pain associated with skeletal
muscle spasms
Majority are central-acting
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CNS is the site of action
Similar in structure and action to other CNS
depressants
Direct-acting
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Act directly on skeletal muscle
Closely resemble GABA
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Muscle Relaxants: Indications
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Relief of painful musculoskeletal conditions
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Muscle spasms
 Management of spasticity of severe chronic
disorders
 Multiple sclerosis, cerebral palsy
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Work best when used along with physical
therapy
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Muscle Relaxants: Indications
(cont’d)
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dantrolene (Dantrium)
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Malignant hyperthermia crisis
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Muscle Relaxants:
Adverse Effects
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Extension of effects on CNS and skeletal
muscles
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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)
Others
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CNS Depressants:
Nursing Implications
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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
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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)
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Check with physician 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)
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Safety is important
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Keep side rails up, or use bed alarms
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Do not permit smoking
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Assist patient with ambulation (especially the
elderly)
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Keep call light within reach
Monitor for adverse effects
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Nursing Implications (cont’d)
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Monitor for therapeutic effects
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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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