drugs affecting
the
central nervous system
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
•Calm or soothe the CNS to the point that they cause sleep
Sedative-Hypnotics—dose dependent:
•At low doses, calm or soothe the CNS without inducing sleep
•At high doses, calm or soothe the CNS
•to the point of causing sleep
Sedative-Hypnotics: Barbiturates
Four categories:
•Ultrashort –mephobexital, thiamylal, thiopental
•Short –pentobarbital, secobarbital
•Intermediate –aprobarbital, butabarbital
•Long –phenobarbital
Barbiturates have a very narrow therapeutic index.
Therapeutic Index
•Dosage range within which the drug is effective but above which is rapidly toxic.
Mechanism of Action
•Site of action:
–Brain stem (reticular formation)
–Cerebral cortex By inhibiting GABA, nerve impulses traveling in the cerebral cortex are also inhibited.
Drug Effects
•Low doses: Sedative effects
•High doses: Hypnotic effects
(also lowers respiratory rate) Notorious enzyme inducers
Therapeutic Uses:
•Hypnotics
•Sedatives
•Anticonvulsants
•Surgical procedures
Side Effects
Body System Effects
CNS Drowsiness, lethargy, vertigo mental depression, coma
Respiratory Respiratory depression, apnea, bronchospasms, cough
GI Nausea, vomiting, diarrhea
Other Agranulocytosis, vasodilation, hypotension, Stevens-Johnson syndrome
Toxicology
•Overdose frequently leads to respiratory depression, and subsequently, respiratory arrest.
•Can be therapeutic:
–Anesthesia induction
–Uncontrollable seizures: “phenobarbital coma”
Drug Interactions
•Additive effects: –ETOH, antihistamines, benzodiazepines, narcotics, tranquilizers
•Inhibited metabolism: –MAOIs will prolong effects of barbiturates
•Increased metabolism: –Reduces anticoagulant response, leading to possible clot formation
CNS Depressants: Benzodiazepines
Most frequently prescribed sedative-hypnotics
•Most commonly prescribed drug classes
•Favorable side effects
•Efficacy
•Safety
Classified as either:
•Sedative-hypnotic or Anxiolytic
(Medication that relieves anxiety)
Sedative-Hypnotic Type
•Long-Acting: –flurazepam (Dalmane), quazepam (Doral)
•Short-Acting: –estazolam (Prosom), temazepam (Restoril),
–triazolam (Halcion)
Anxiolytic Type
•alprazolam (Xanax)
•chloridiazepoxide (Librium)
•diazepam (Valium)
•lorazepam (Ativan)
•midazolam (Versed)
*zolpidem (Ambien) and zaleplon (Sonata) (nonbenzodiazepine hypnotic agents, share characteristics)
Drug Effects
•Calming effect on the CNS
•Useful in controlling agitation and anxiety
Therapeutic Uses
•Sedation
•Sleep induction
•Skeletal muscle relaxation
•Anxiety relief
•Treatment of alcohol withdrawal
•Agitation
•Depression
•Epilepsy
•Balanced anesthesia
Side Effects
•Mild and infrequent
Headache
Drowsiness
Dizziness
Vertigo
Lethargy
Paradoxical excitement (nervousness) “Hangover effect”
Nursing Implications
•Before beginning therapy, perform 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.
•Give 15 to 30 minutes before bedtime for maximum effectiveness in inducing sleep.
•Most benzodiazepines (except flurazepam) cause REM rebound and a tired feeling the next day; use with caution in the elderly.
•Patients should be instructed to avoid alcohol and other CNS depressants.
•Check with physician before taking any other medications, including OTC medications.
•It may take 2 to 3 weeks to notice improved sleep when taking barbiturates.
•Abruptly stopping these medications, especially barbiturates, may cause rebound insomnia.
•Safety is important:
–Keep side rails up
–Do not permit smoking
–Assist patient with ambulation (especially the elderly)
–Keep call light within reach
•Monitor for side effects
•Monitor for therapeutic effects
–Increased ability to sleep at night
–Fewer awakenings
–Shorter sleep induction time
–Few side effects, such as hangover effects
–Improved sense of well-being because of improved sleep
•Drugs that have an inhibitory effect on the CNS to the degree that they reduce:
–Nervousness
–Excitability
–Irritability
–without causing sleep
Hypnotics
•Calm or soothe the CNS to the point that they cause sleep
Sedative-Hypnotics—dose dependent:
•At low doses, calm or soothe the CNS without inducing sleep
•At high doses, calm or soothe the CNS
•to the point of causing sleep
Sedative-Hypnotics: Barbiturates
Four categories:
•Ultrashort –mephobexital, thiamylal, thiopental
•Short –pentobarbital, secobarbital
•Intermediate –aprobarbital, butabarbital
•Long –phenobarbital
Barbiturates have a very narrow therapeutic index.
Therapeutic Index
•Dosage range within which the drug is effective but above which is rapidly toxic.
Mechanism of Action
•Site of action:
–Brain stem (reticular formation)
–Cerebral cortex By inhibiting GABA, nerve impulses traveling in the cerebral cortex are also inhibited.
Drug Effects
•Low doses: Sedative effects
•High doses: Hypnotic effects
(also lowers respiratory rate) Notorious enzyme inducers
Therapeutic Uses:
•Hypnotics
•Sedatives
•Anticonvulsants
•Surgical procedures
Side Effects
Body System Effects
CNS Drowsiness, lethargy, vertigo mental depression, coma
Respiratory Respiratory depression, apnea, bronchospasms, cough
GI Nausea, vomiting, diarrhea
Other Agranulocytosis, vasodilation, hypotension, Stevens-Johnson syndrome
Toxicology
•Overdose frequently leads to respiratory depression, and subsequently, respiratory arrest.
•Can be therapeutic:
–Anesthesia induction
–Uncontrollable seizures: “phenobarbital coma”
Drug Interactions
•Additive effects: –ETOH, antihistamines, benzodiazepines, narcotics, tranquilizers
•Inhibited metabolism: –MAOIs will prolong effects of barbiturates
•Increased metabolism: –Reduces anticoagulant response, leading to possible clot formation
CNS Depressants: Benzodiazepines
Most frequently prescribed sedative-hypnotics
•Most commonly prescribed drug classes
•Favorable side effects
•Efficacy
•Safety
Classified as either:
•Sedative-hypnotic or Anxiolytic
(Medication that relieves anxiety)
Sedative-Hypnotic Type
•Long-Acting: –flurazepam (Dalmane), quazepam (Doral)
•Short-Acting: –estazolam (Prosom), temazepam (Restoril),
–triazolam (Halcion)
Anxiolytic Type
•alprazolam (Xanax)
•chloridiazepoxide (Librium)
•diazepam (Valium)
•lorazepam (Ativan)
•midazolam (Versed)
*zolpidem (Ambien) and zaleplon (Sonata) (nonbenzodiazepine hypnotic agents, share characteristics)
Drug Effects
•Calming effect on the CNS
•Useful in controlling agitation and anxiety
Therapeutic Uses
•Sedation
•Sleep induction
•Skeletal muscle relaxation
•Anxiety relief
•Treatment of alcohol withdrawal
•Agitation
•Depression
•Epilepsy
•Balanced anesthesia
Side Effects
•Mild and infrequent
Headache
Drowsiness
Dizziness
Vertigo
Lethargy
Paradoxical excitement (nervousness) “Hangover effect”
Nursing Implications
•Before beginning therapy, perform 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.
•Give 15 to 30 minutes before bedtime for maximum effectiveness in inducing sleep.
•Most benzodiazepines (except flurazepam) cause REM rebound and a tired feeling the next day; use with caution in the elderly.
•Patients should be instructed to avoid alcohol and other CNS depressants.
•Check with physician before taking any other medications, including OTC medications.
•It may take 2 to 3 weeks to notice improved sleep when taking barbiturates.
•Abruptly stopping these medications, especially barbiturates, may cause rebound insomnia.
•Safety is important:
–Keep side rails up
–Do not permit smoking
–Assist patient with ambulation (especially the elderly)
–Keep call light within reach
•Monitor for side effects
•Monitor for therapeutic effects
–Increased ability to sleep at night
–Fewer awakenings
–Shorter sleep induction time
–Few side effects, such as hangover effects
–Improved sense of well-being because of improved sleep