1. Drugs for anxiety disorders

Question 1

Types of drugs for anxiety disorders

Answer 1

1. Benzodiazepines

2. Selective serotonin reuptake inhibitors (SSRIs)

Question 2

MOA of benzodiazepines

Answer 2

Benzodiazepines are indirect GABA-A receptor agonists that bind to GABA-A receptors → ↑ affinity of GABA to bind to GABA-A receptors → ↑ GABA action → ↑ opening frequency of chloride channels → hyperpolarization of the postsynaptic neuronal membrane → ↓ neuronal excitability

Question 3

Types of benzodiazepines

Answer 3

1. short acting : midazolam
2. intermediate acting : lorazepam, alprazolam
3. longer acting : diazepam, clonazepam

Question 4

Pharmacokinetics of benzodiazepines

Answer 4

Absorption:

1. Oral: fast onset: 0.5 - 1 hr
2. Parenteral: IV for midazolam, lorazepam, diazepam

Question 5

Adverse effects of benzodiazepines

Answer 5

1. CNS: Increased drowsiness, decreased motor skills, increased reaction time
2. CNS: anterograde amnesia. Memory disturbances are particularly profound after intravenous sedation
3. CVS: Decreased BP, decreased respiration in predisposed patients
4. Paradoxical effects: excitement, garrulousness, irritability, hallucination, outburst of rage. Violent behaviour has been attributed to disinhibition by BZD (behaviour normally suppressed)
5. Neonatal toxicity: Floppy child syndrome
6. Tolerance, dependence, and withdrawal

Question 6

What other uses does benzodiazepines have other than for anxiety?

Answer 6

Insomnia

Question 7

Characteristics of Benzodiazepines - induced sleep

Answer 7

Reduced REM and deep (stage 4) sleep when compared to natural sleep