BENZODIAZEPINES

Question 1

What is the mechanism of action of benzodiazepines?

Answer 1

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.

Question 2

What are the clinical properties of benzodiazepines that they are used?

Answer 2

Sedation

Hypnotic

Anxiolytic

Anticonvulsant

Muscle relaxant

Question 3

Benzodiazepines can be short acting, medium acting or long acting based on half-life. Give an example of a commonly used short acting benzodiazepine.

Answer 3

Midazolam

Question 4

Benzodiazepines can be short acting, medium acting or long acting based on half-life. Give an example of a commonly used medium acting benzodiazepine.

Answer 4

Lorazepam

Question 5

Benzodiazepines can be short acting, medium acting or long acting based on half-life. Give an example of a commonly used long acting benzodiazepine.

Answer 5

Diazepam

Question 6

Why are benzodiazepines not prescribed long term?

Answer 6

Patients commonly develop tolerance and dependence to benzodiazepines.

Question 7

What are the guidelines surrounding the withdrawal of benzodiazepines?

Answer 7

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

Question 8

What are the clinical features of benzodiazepine withdrawal syndrome?

Answer 8

Very similar to alcohol withdrawal syndrome:

Insomnia

Irritability

Anxiety

Tremor

Loss of apetite

Tinnitus

Perspiration

Perceptual disturbance

Seizures

Question 9

What are the conditions that benzodiazepines are used in?

Answer 9

Status epilepticus

Alcohol withdrawal

Restless leg syndrome

Question 10

In which groups of patients are benzodiazepines contraindicated?

Answer 10

Breast feeding women

Can precipitate attack in those with acute intermittent porphyria

Question 11

What are the early features of benzodiazepine toxicity?

Answer 11

Early signs (much like being drunk):

Intoxication

Somnolence (drowsy)

Diplopia

Impaired balance

Impaired motor function

Anterograde amnesia

Ataxia

Slurred speech

Question 12

What are the later more severe features of benzodiazepine toxicity?

Answer 12

Prolonged deep coma or deep cyclic coma

Apnea or respiratory depression

Hypoxemia

Hypothermia

Hypotension

Bradycardia

Cardiac arrest

Pulmonary aspiration

Death

Question 13

How do we medically manage someone who has taken an overdose of benzodiazepines?

Answer 13

Flumazenil