Module 3 Central Nervous System Depressants

Question 1

CNS Depressants

Answer 1

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

Question 2

Sleep

Answer 2

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

Question 3

CNS Depressants:

Benzodiazepines

Answer 3

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

Question 4

Benzodiazepines:

Classification

Answer 4

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

Question 5

Benzodiazepines:

Sedative-Hypnotic Types

Answer 5

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

Question 6

CNS Depressants:

Nonbenzodiazepine Hypnotics

Answer 6

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

Question 7

CNS Depressants:

Nonbenzodiazepine Hypnotics

Answer 7

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

Question 8

Benzodiazepines:

Mechanism of Action

Answer 8

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

Question 9

Benzodiazepines:

Drug Effects

Answer 9

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

Question 10

Benzodiazepines:

Indications

Answer 10

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

Question 11

Benzodiazepines: Adverse

Effects

Answer 11

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

Question 12

Benzodiazepines:

Toxicity and Overdose

Answer 12

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

Question 13

Herbal Products: Kava

Answer 13

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

Question 14

Herbal Products: Valerian

Answer 14

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

Question 15

Sedative-Hypnotics: Barbiturates

Answer 15

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

Question 16

Therapeutic Index

Answer 16

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

Question 17

Barbiturates:

Mechanism of Action

Answer 17

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

Question 18

Barbiturates: Drug Effects

Answer 18

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

Question 19

Barbiturates: Indications

Answer 19

Hypnotics
 Sedatives
 Anticonvulsants
 Anesthesia for surgical procedures

Question 20

Barbiturates: Four Categories

Answer 20

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

Question 21

Barbiturates: Four Categories

cont’d

Answer 21

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

Question 22

Barbiturates: Onset and Duration

Answer 22

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

Question 23

Barbiturates: Adverse Effects

Answer 23

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

Question 24

Barbiturates:

Toxicity and Overdose

Answer 24

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

Question 25

Barbiturates:

Drug Interactions

Answer 25

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

Question 26

Muscle Relaxants

Answer 26

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

Question 27

Muscle Relaxants: Indications

Answer 27

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

Question 28

Muscle Relaxants: Adverse

Effects

Answer 28

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

Question 29

Common Muscle Relaxants

Answer 29

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