Benzodiazepines Flashcards
What is the mechanism of action of benzodiazepines?
Bind to alpha subunit of GABA receptor on chloride channels thereby increasing the affinity for GABA. This leads to an increase in the frequency with which chloride channels open.
What are the clinical properties of benzodiazepines that they are used?
Sedation
Hypnotic
Anxiolytic
Anticonvulsant
Muscle relaxant
Benzodiazepines can be short acting, medium acting or long acting based on half-life. Give an example of a commonly used short acting benzodiazepine.
Midazolam
Benzodiazepines can be short acting, medium acting or long acting based on half-life. Give an example of a commonly used medium acting benzodiazepine.
Lorazepam
Benzodiazepines can be short acting, medium acting or long acting based on half-life. Give an example of a commonly used long acting benzodiazepine.
Diazepam
Why are benzodiazepines not prescribed long term?
Patients commonly develop tolerance and dependence to benzodiazepines.
What are the guidelines surrounding the withdrawal of benzodiazepines?
Dose should be reduced in steps of about 1/8th every fortnight.
A suggested protocol for patients experiencing difficulty is given:
- Switch patients to the equivalent dose of diazepam
- Reduce dose of diazepam every 2-3 weeks in steps of 2 or 2.5 mg
- Time needed for withdrawal can vary from 4 weeks to a year or more
What are the clinical features of benzodiazepine withdrawal syndrome?
Very similar to alcohol withdrawal syndrome:
Insomnia
Irritability
Anxiety
Tremor
Loss of apetite
Tinnitus
Perspiration
Perceptual disturbance
Seizures
What are the conditions that benzodiazepines are used in?
Status epilepticus
Alcohol withdrawal
Restless leg syndrome
In which groups of patients are benzodiazepines contraindicated?
Breast feeding women
Can precipitate attack in those with acute intermittent porphyria
What are the early features of benzodiazepine toxicity?
Early signs (much like being drunk):
Intoxication
Somnolence (drowsy)
Diplopia
Impaired balance
Impaired motor function
Anterograde amnesia
Ataxia
Slurred speech
What are the later more severe features of benzodiazepine toxicity?
Prolonged deep coma or deep cyclic coma
Apnea or respiratory depression
Hypoxemia
Hypothermia
Hypotension
Bradycardia
Cardiac arrest
Pulmonary aspiration
Death
How do we medically manage someone who has taken an overdose of benzodiazepines?
Flumazenil