Pharmacology of Anxiolytic Drugs Flashcards
(37 cards)
Give some examples of benzodiazepines.
Midazolam (Hypnovel)
Lorazepam (Ativan)
Loprazolam
Oxazepam
What are the pharmacological effects of benzodiazepines?
- Reduce anxiety and aggression.
- Hypnosis/sedation.
- Muscle relaxation.
- Anticonvulsant effect.
- Anterograde amnesia (loss of ability to form new memories).
What is the choice of benzodiazepine determined by?
Duration of action
How do all benzodiazepines act?
By increasing GABA-mediated inhibition
What is GABA (in the brain)?
The main inhibitory transmitter in the brain
What does GABA stand for?
Gamma Amino Butyric Acid
GABA has a __________ distribution
WIDESPREAD
Where is glycine restricted to?
The spinal cord and brain stem.
What does GABA cause in target cells?
Hyperpolarisation
Describe the action of benzodiazepines.
Act by enhancing the action of GABA at the GABAA receptor (increased inhibition)
Is the GABA binding site and the benzodiazepine binding site the same?
NO
NICE say that use of benzodiazepines should not exceed what?
4 weeks
Give 3 examples of substances which exhibit anxiolytic properties in humans +/or some animal tests of anxiety.
Ethanol, neurosteroids and barbiturates
What have anxiogenic properties?
Inverse BDZ agonists ie. β-carbolines
Name a drug that can increase anxiety.
Flumazenil (antagonist).
In behavioural tests, drugs which do what have been shown to be weak anxiolytics?
Drugs which increase GABA concentration in the brain, or act directly on GABAA receptors.
Benzodiazepines are fairly safe in overdose. Explain this.
Alone, they are unlikely to cause respiratory depression
Name a benzodiazepine antagonist.
Flumazenil.
What happens of withdrawal of benzodiazepines?
Rebound anxiety and sometimes physical symptoms
Outline 3 specific problems with benzodiazepines.
- Cause paradoxical aggression – due to disinhibition.
- anterograde amnesia and impaired co-ordination (beware rohypnol).
- Cause tolerance and dependence.
Benzodiazepines should be used for a max of ____ weeks
FOUR
What may rapid withdrawal of benzodiazepines cause?
Confusion, toxic psychosis and even convulsions
ALSO- insomnia, subjective anxiety, insomnia, loss of appetite and body weight, tremor, perspiration, tinnitus, and perceptual disturbances
Aside from rapid withdrawal of benzodiazepines, what can also cause withdrawal symptoms?
Neuroadaptation of the GABA response:
Chronic treatment causes decreased response to GABA, so withdrawal results in anxiety/convulsions possibly due to decreased density of BZ receptors.
Outline how a patient should safely be withdrawn from benzodiazepines.
- Transfer patient to equivalent daily dose of diazepam/chlordiazepoxide, preferably taken at night.
- Reduce dose every 2–3 weeks in steps of 2 or 2.5 mg; if withdrawal symptoms occur, maintain this dose until symptoms improve.
- Reduce dose further, if necessary in smaller steps; it is better to reduce too slowly rather than too quickly.
- Stop completely; time needed for withdrawal can vary from about 4 weeks to a year or more.
