chapter 13 cns depressant and muscle relaxants - week 5

Question 1

Central Nervous System Depressants

Answer 1

Sedatives
Drugs that have an inhibitory effect on the 
central nervous system (CNS) to the degree that they reduce:
Nervousness
Excitability
Irritability
Hypnotics
Cause sleep
Have much more potent effect on CNS than sedatives have
A sedative can become a hypnotic if given in large enough doses.

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

Question 2

Sleep

Answer 2

Normal sleep is cyclic and repetitive.
A sleeping person’s response to stimuli is markedly reduced.
Sleep architecture
Rapid eye movement (REM) sleep
Non-REM sleep
REM interference
REM rebound

Question 3

CNS Depressants: Benzodiazepines

Answer 3

Formerly the most commonly prescribed sedative–hypnotic drugs
Nonbenzodiazepines currently more frequently prescribed
Favourable adverse effect profiles, efficacy, and safety
Classified as either sedative–hypnotic or anxiolytic (medication that relieves anxiety)

Question 4

Benzodiazepines:
Sedative–Hypnotic Types

Answer 4

Long acting
clonazepam (Rivotril®), diazepam (Valium®), flurazepam hydrochloride (Dalmane®)
Intermediate acting
alprazolam (Xanax®), bromazepam (Lectopam®), lorazepam (Ativan®), temazepam (Restoril®)
Short acting
midazolam hydrochloride, triazolam, zolpidem tartrate (Sublinox®)

Question 5

Benzodiazepines: Mechanism of Action

Answer 5

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

Question 6

Benzodiazepines: Drug Effects

Answer 6

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

Question 7

Benzodiazepines: Indications

Answer 7

Sedation
Sleep induction
Skeletal muscle relaxation
Agitation or anxiety relief
Anxiety-related depression

Question 8

Benzodiazepines: Uses

Answer 8

Treatment of acute seizure disorders
Treatment of alcohol withdrawal
Short-term therapy for insomnia

Question 9

Benzodiazepines: 
Adverse Effects

Answer 9

Mild and infrequent
Headache
Drowsiness
Paradoxical excitement of nervousness
Dizziness
Cognitive impairment
Vertigo
Lethargy
Fall hazard for older adults
“Hangover” effect or daytime sleepiness

Question 10

Benzodiazepines: 
Toxicity and Overdose

Answer 10

Somnolence
Confusion
Coma
Diminished reflexes
Rarely results in hypotension and respiratory depression unless taken with other CNS depressants
Treatment symptomatic and supportive
Flumazenil as an antidote

Question 11

Benzodiazepines: 
Interactions

Answer 11

Azole antifungals, verapamil, diltiazem, protease inhibitors, macrolide antibiotics, grapefruit juice
CNS depressants (alcohol, opioids, muscle relaxants)
Kava and valerian
Food–drug interactions with grapefruit and grapefruit juice

Question 12

diazepam (Valium®)

Answer 12

First clinically available benzodiazepine drug. It has varied uses, including treatment of anxiety.

Question 13

Midazolam

Answer 13

Most commonly used preoperatively and for procedural sedation
Causes amnesia and anxiolysis (reduced anxiety) as well as sedation
Normally administered by IV in adults
Liquid oral dosage form is also available for children.

Question 14

temazepam (Restoril®)

Answer 14

Intermediate-acting benzodiazepine
One of the metabolites of diazepam
Normally induces sleep within 20 to 40 minutes
Long onset of action, so it is recommended that patients take it about 1 hour prior to going to bed.
Still an effective hypnotic; however, it has been replaced by newer drugs.

Question 15

nonbenzodiazepine: Ramelteon®

Answer 15

Structurally similar to the hormone melatonin; works as an agonist at melatonin receptors in the CNS
Not available in Canada.
Technically, not a CNS depressant; used as hypnotic
Not classified as a controlled substance
Indicated for patients who have difficulty with sleep onset rather than maintenance

Question 16

Nonbenzodiazepine: zopiclone (Imovane®, Rhovane®)

Answer 16

Short-acting benzodiazepinelike drug
Unique advantage of this drug stems from its very short half-life.
Short-term treatment of insomnia, 7 to 10 days.

Question 17

Nonbenzodiazepine: zolpidem tartrate (Sublinox®)

Answer 17

Short-acting nonbenzodiazepine hypnotic
Lower incidence of daytime sleepiness compared with benzodiazepine hypnotics
Onset of action approximately 30 minutes

Question 18


Herbal Products: Kava 


Answer 18

Used to relieve anxiety, stress, and restlessness and to promote sleep
May cause temporary yellow skin discoloration (extended, continued intake), scaly skin, 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.

Question 19


Herbal Products: Valerian 


Answer 19

Used to relieve anxiety, restlessness, and sleep disorders
May cause CNS depression, hepatotoxicity, nausea, vomiting, anorexia, headache, restlessness, insomnia
Many interactions, including with CNS depressants, monoamine oxidase inhibitors (MAOIs), phenytoin, warfarin, and alcohol
Contraindicated in cardiac and liver disease
Patient should not operate heavy machinery during use.

Question 20

Barbiturates

Answer 20

First introduced in 1903; were the standard drugs for insomnia and sedation
Habit forming; low therapeutic index
Only a few commonly used today partly because of the safety and efficacy of benzodiazepines

Question 21

Barbiturates: 
Mechanism of Action

Answer 21

Site of action: brainstem (reticular formation)
By potentiating the action of GABA, nerve impulses traveling in the cerebral cortex are inhibited.

Question 22

Barbiturates: Indications

Answer 22

Sedatives
Anticonvulsants
Anaesthesia for surgical procedures

Question 23

Barbiturates: Adverse Effects

Answer 23

Body system/adverse effects
Cardiovascular: Vasodilation, hypotension
CNS: Drowsiness, lethargy, vertigo
Respiratory: Respiratory depression, cough
Gastrointestinal: Nausea, vomiting, diarrhea, constipation
Hematological: Agranulocytosis, thrombocytopenia
Other: Hypersensitivity reactions, Stevens-Johnson syndrome

Question 24

Barbiturates:
Toxicity and Overdose

Answer 24

Rarely used
Overdose frequently leads to respiratory depression and subsequent respiratory arrest
Overdose produces CNS depression (sleep to coma and death)
Can be therapeutic for:
Anaesthesia induction
Uncontrollable seizures
Pentobarbital or phenobarbital coma

Treatment of overdose
Symptomatic and supportive
Maintain adequate airway
Assisted ventilation or oxygen therapy
Fluids
Alkalization
Activated charcoal

Question 25

Barbiturates: Drug Interactions

Answer 25

Additive effects
Alcohol, antihistamines, benzodiazepines, opioids, tranquilizers
Inhibited metabolism
MAOIs prolong the effects of barbiturates.
Increased metabolism
Reduces anticoagulant response, leading to possible clot formation

Question 26

Common Barbiturates

Answer 26

pentobarbital sodium
phenobarbital

Question 27

Phenobarbital

Answer 27

Prototypical barbiturate
Long-acting drug
Uses: prevention of generalized tonic-clonic seizures and fever-induced convulsions, as well as treatment of hyperbilirubinemia in neonates
Rarely used today as a sedative and is no longer recommended to be used as a hypnotic drug

Question 28

Over-the-Counter Hypnotics

Answer 28

Nonprescription sleeping aids often contain antihistamines, which have CNS-depressant effect.
Doxylamine succinate (Unisom-2®), diphenhydramine hydrochloride (Sleep-Eze®), acetaminophen/diphenhydramine (Extra Strength Tylenol® Nighttime)
As with other CNS depressants, concurrent use of alcohol can cause respiratory depression or arrest.

Question 29


Muscle Relaxants 


Answer 29

Act to relieve pain associated with skeletal muscle spasms
Majority are centrally acting
Site of action: CNS
Similar in structure and action to other CNS depressants
Direct acting
Act directly on skeletal muscle
Closely resemble GABA

Question 30

Muscle Relaxants: Indications

Answer 30

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

Question 31

Muscle Relaxants: 
Adverse Effects

Answer 31

Extension of effects on CNS and skeletal muscles
Euphoria
Lightheadedness
Dizziness
Drowsiness
Fatigue
Confusion
Muscle weakness, others

Question 32


Common Muscle Relaxants 


Answer 32

Baclofen (Lioresal®)
Cyclobenzaprine hydrochloride (Novo-Cycloprine®)
Dantrolene sodium (Dantrene®)
Tizanidine hydrochloride

Question 33

Nursing Implications muscle relaxaces

Answer 33

Before beginning therapy, obtain a thorough history regarding allergies, use of other medications, health history, and medical history.
Obtain baseline vital signs and intake and output, including supine and erect blood pressure.
Assess for potential disorders and conditions that may be contraindications and for potential drug interactions.
Administer 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 older adults.
Instruct patients to avoid alcohol and other CNS depressants.
Check with the 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.
Safety is important.
Keep side rails up or use bed alarms.
Do not permit smoking.
Assist patients (especially older adults) with ambulation .
Keep call light within reach.
Monitor for adverse effects.
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, pain relief