Anxiolytics Flashcards
What class of drugs are anxiolytics
Benzodiazepines
Barbiturates
What is the MOA for benzodiazepines and what are they used as
Enhance GABA transmission at GABA-A receptor by increasing the duration of opening
Uses: sedation, hypnotic, anxiolytic, anticonvulsant, muscle relaxant
What is the difference between benzodiazepines and barbiturates
Binding sites and mechanisms:
- Barbs increase the FREQUENCY of opening
- BZDs increase the DURATION of opening
Barbs are less selective:
- Less excitatory transmission
- Barbs are MORE dangerous (i.e. induction of surgical anaesthesia and small therapeutic window)
Give examples of benzodiazepines and which has the shortest half life
Diazepam
Lorazepam (shortest half-life)
Chlordiazepoxide
Nitrazepam
Oxazepam (used in hepatic impariement)
What is the significance of lorazepam’s half life
Lorazepam has the shortest half-life → more potent effects when withdrawing so switch to longer-acting BDZ, such as diazepam, before starting the withdrawal process
How long should anxiolytics be prescribed for
Never more than 2-4w
What are z-drugs and give an example
Benzodiazepines that treat insomnia (Severe/disabling)
e.g. zopiclone
What are the side effects of z-drugs
Agitation
Bitter taste
Constipation
Dizziness
Eating is hard (dry mouth)
Falls (increased risk)
Hypotonia
What are the side effects of benzodiazepines
Sedation, confusion, anterograde amnesia, ataxia
Potentiates other CNS depressants (i.e. alcohol)
Tolerance (less than barbs) and dependence (less intense than barbs)
Free plasma concentration increases when co-administered with aspirin, heparin
Use in pregnancy: Cleft lip (1st trimester use)
What are the benefits of benzodiazepines
Wide therapeutic window – overdose →prolonged sleep
Flumazenil is a BDZ antagonist and can reverse effect
Only a mild effect on REM sleep
Does not induce liver enzyme
How should benzodiazepines be withdrawn
Options:
(1) Slow-dose reduction
(2) Switch to equivalent dose of Diazepam, and slow-dose reduction; used in those…
- Difficult to physically taper down the dose
- On short-acting potent BDZs (i.e. lorazepam)
Slow dose
1/8th daily dose reduction every 2 weeks – e.g. diazepam 40 mg per day
- Reduce dose by 5 mg every 2 weeks until reaching 20 mg per day, then 8 weeks
- Reduce dose by 2 mg every 2 weeks until reaching 10 mg per day, then 10 weeks
- Reduce dose by 1 mg every 2 weeks until reaching 5 mg per day, then 10 weeks
- Reduce dose by 0.5 mg every 2 weeks until completely stopped 20 weeks
Can take 3 months to a year or longer if needed
What is the difference between a sedative and hypnotic
Sedative – reduce mental and physical activity without producing a loss of consciousness
Hypnotic – reduce mental and physical activity → induce sleep
Give examples of sedatives/hypnotics
Temazepam (BDZ)
Oxazepam (BDZ)
Nitrazepam = hypnotic effect at night followed by an anxiolytic effect during the day
What are the symptoms of benzodiazepine use
Calm, mild euphoria
Slurred speech
Ataxia
Stupor
What are the S/S of benzodiazpine overdose
Low GCS
Low BP
Mydriasis
Hyporeflexia
