CNS Deppressants Flashcards
What are sedatives?
Drugs that have an inhibitory effect on the CNS until they reduce:
- Nervousness
- Excitability
- Irritability
Without causes sleep
What’s an hypnotic?
Reduce CNS function to the point that they cause sleep
A sedative can become a hypnotic if given a large enough doses
What is a more commonly used sedative-hypnotic?
Benzodiazepines
- Better pharmacological profile
- Better adverse effects profile
Which sedative-hypnotic is addictive?
Barbiturates
When should you use Barbiturates?
Antiepileptic
- Can raise the seizure threshold - reducing seizures
- Anaesthesia for surgical procedures (short)
Narrow therapeutic index
What is an example of a short acting, and a long acting barbiturate?
- Pentobarbital (rarely used)
- Short acting
- Phenobarbital
- Long acting
- Antiepileptic
How do Barbiturates function?
- Most have a broad CNS depression action
- Potentiates GABA action and mimics GABA
- Metabolized in liver and excreted in urine
What is the antidote to barbiturates?
Activated charcoal
How do barbiturates impact enzymes?
- Notorious enzyme inducers
- Increase liver enzymes that metabolize many drugs
What are some drug interactions for barbiturates?
Lots of drug-drug interactions
- Use cautiously
- Additive effects (other CNS depressants)
- Alcohol, antihistamines, benzodiazepines, opioids
Inhibited metabolism
- MAOIs will prolong effects of barbiturates
- Increased metabolism of other drugs
- Reduces anticoagulant response of warfarin
- Theophylline, phenytoin also reduce effects
What are the adverse effects of barbiturates?
Similar to alcohol intoxication
- Confusion, impaired judgement and speech, retarded reflexes, loss of muscle coordination
CNS
- Drowsiness, lethargy, vertigo, mental depression, coma
Resp
- Respiratory Depression, apnea, bronchospasm, cough
GI
- Nausea, vomiting, diarrhea, constipation
Other
- Agranulocytosis (loss of WBC), vasodilation, hypotension, Stevens-Johnson syndrome
- Reduces REM sleep causes agitation and inability to deal with normal stress
What happens with barbiturates overdose?
- Leads to respiratory depression or arrest
- CNS depression (sleep-coma-death)
Why are barbiturates used less in clinical situations?
- Tolerance
- Physical dependence
- Liver enzyme induction
- *Abuse potential
- Powerful respiratory depressants
- No antidote
What are the two classifications of benzodiazepines?
- Sedative-hypnotic
- Anxiolytic
What are the different acting classes of benzodiazepines?
Long acting
- Chlordiazepoxide, clorazepate, flurazepam
Intermediate acting
- *Lorazepam (ativan), oxazepam
Short acting
- *Midazolam IV (Versed), triazolam
- Conscious sedation - amnesic property
Which neurotransmitter do benzodiazepines enhance?
GABA
- Reduces excitability of neurons and depresses CNS activity
How do benzodiazepines impact the body?
Affect hypothalamic, thalamic, and limbic systems of the brain
- *Does not suppress REM as much as barbiturates
- *Does not increase metabolism of other drugs
- *PO admin does not depress respiration excessivley
Reduce excessive sensory stimulation, inducing sleep especially in short term use for insomnia due to anxiety
Much better than barbiturates
What is the antidote for benzodiazepines?
Flumazenil
When should benzodiazepines be used?
Sedation Sleep induction Skeletal muscle relaxation (central effect) Anxiety relief Treatment of alcohol withdrawal Agitation Epilepsy Balanced anaesthesia
What are some adverse effects for benzodiazepines?
*Drowsiness Headache Dizziness Vertigo Lethargy Paradoxical excitement (nervousness) “Hangover effect”
What are the drug interactions with benzodiazepines?
All other CNS depressants have additive effects
- Alcohol, opioids
Grapefruit alter drug absorption
Cimetidine inhibits benzodiazepine metabolism
What are some other hypnotics?
Zolpidem (Ambien), zaleplon, zopiclone
Used for short-term use in management of insomnia
When should muscle relaxants be used?
For the relief of painful musculoskeletal conditions
- Muscle spasms
- Management of spasticity of severe clinical disorders
- MS, cerebral palsy
- Dantrolene
- For emergency treatment of malignant hyperthermia crisis
- Treatment of spasticity associated with spinal cord injury, CVA, CP and MS
- Acts directly on skeletal muscles causing relaxation
- Especially effective for head and neck spasms
What are some adverse effects of muscle relaxants?
Euphoria Lightheadedness Dizziness Drowsiness Fatigue Muscle weakness
