Central Nervous System Depressants
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Sedatives
Drugs that have an inhibitory effect on the CNS to the degree that they reduce: ◦ ◦ ◦ ◦
Nervousness Excitability Irritability without causing sleep
CNS Depressants www.indiandentalacademy.com
Hypnotics ď‚—
Calm or soothe the CNS to the point that they cause sleep
CNS Depressants www.indiandentalacademy.com
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
CNS Depressants www.indiandentalacademy.com
First introduced in 1903, standard agents for insomnia and sedation Habit-forming Only a handful commonly used today due in part to the safety and efficacy of: BENZODIAZEPINES
Sedative-Hypnotics: Barbiturates www.indiandentalacademy.com
Four categories:
Ultrashort ◦ mephobexital, thiamylal, thiopental
Short ◦ pentobarbital, secobarbital
Intermediate ◦ aprobarbital, butabarbital
Long ◦ phenobarbital
Sedative-Hypnotics: Barbiturates www.indiandentalacademy.com
Barbiturates have a very narrow therapeutic index.
Therapeutic Index ď‚—
Dosage range within which the drug is effective but above which is rapidly toxic.
Sedative-Hypnotics: Barbiturates www.indiandentalacademy.com
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.
Sedative-Hypnotics: Barbiturates www.indiandentalacademy.com
Drug Effects ď‚—
Low doses:
Sedative effects
ď‚—
High doses:
Hypnotic effects (also lowers respiratory rate)
Notorious enzyme inducers
Sedative-Hypnotics: Barbiturates www.indiandentalacademy.com
Therapeutic Uses
Hypnotics Sedatives Anticonvulsants Surgical procedures
Sedative-Hypnotics: Barbiturates www.indiandentalacademy.com
Side Effects Body System
Effects
CNS
Drowsiness, lethargy, vertigo mental depression, coma
Respiratory apnea,
Respiratory depression, bronchospasms, cough
Sedative-Hypnotics: Barbiturates www.indiandentalacademy.com
Side Effects Body System GI Other
Effects Nausea, vomiting, diarrhea Agranulocytosis, vasodilation, hypotension, Stevens-Johnson syndrome
Sedative-Hypnotics: Barbiturates www.indiandentalacademy.com
Toxicology
Overdose frequently leads to respiratory depression, and subsequently, respiratory arrest. Can be therapeutic: ◦ Anesthesia induction ◦ Uncontrollable seizures: “phenobarbital coma”
Sedative-Hypnotics: Barbiturates www.indiandentalacademy.com
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
Sedative-Hypnotics: Barbiturates www.indiandentalacademy.com
Most frequently prescribed sedativehypnotics
Most commonly prescribed drug classes Favorable side effects Efficacy Safety
CNS Depressants: Benzodiazepines www.indiandentalacademy.com
Classified as either: CNS Depressants: ď‚— Sedative-hypnotic or Anxiolytic
Benzodiazepines
(Medication that relieves anxiety)
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Sedative-Hypnotic Type
Long-Acting: ◦ flurazepam (Dalmane), quazepam (Doral)
Short-Acting: ◦ estazolam (Prosom), temazepam (Restoril), ◦ triazolam (Halcion)
CNS Depressants: Benzodiazepines www.indiandentalacademy.com
Anxiolytic Type
alprazolam (Xanax) chloridiazepoxide (Librium) diazepam (Valium) lorazepam (Ativan) midazolam (Versed) zolpidem (Ambien) and zaleplon (Sonata)
CNS Depressants: (nonbenzodiazepine hypnotic agents, share characteristics) Benzodiazepines www.indiandentalacademy.com
Mechanism of Action
Depress CNS activity Affect hypothalamic, thalamic, and limbic systems of the brain Benzodiazepine receptors
CNS Depressants: Benzodiazepines www.indiandentalacademy.com
Drug Effects ď‚— Calming effect on the CNS ď‚— Useful in controlling agitation and anxiety
CNS Depressants: Benzodiazepines www.indiandentalacademy.com
Therapeutic Uses
Sedation
Sleep induction
Skeletal muscle relaxation
Anxiety relief
Treatment of alcohol withdrawal
Agitation
Depression
Epilepsy CNS Depressants: Balanced anesthesia Benzodiazepines www.indiandentalacademy.com
Side Effects
Mild and infrequent Headache
Drowsiness Vertigo
Dizziness Lethargy
Paradoxical excitement (nervousness) “Hangover effect”
CNS Depressants: Benzodiazepines www.indiandentalacademy.com
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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.
CNS Depressants: Nursing Implications www.indiandentalacademy.com
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.
CNS Depressants: Nursing Implications www.indiandentalacademy.com
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.
CNS Depressants: Nursing Implications www.indiandentalacademy.com
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
CNS Depressants: Nursing Implications www.indiandentalacademy.com
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
CNS Depressants: Nursing Implications www.indiandentalacademy.com
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