Benzodiazepine

Question 1

What is MoA of benzodiazepine

Answer 1

direct GABA agonists (increase Cl- channel opening hyper-polarise postsynaptic neurons decrease neuronal excitability) leading to:
- Sedation
- Anxiolytic
- Hypnotic
- Muscle relaxant / Anticonvulsant

Question 2

Give 3 examples of short acting benzo and indications, duration of action

Answer 2

Midazolam, Oxazepam, Triazolam
12 hours
Indication
- Procedural sedation
o Sleep-onset insomnia

Question 3

Give examples of intermediate acting benzodiazepine, typical dose and indications plus duration of action

Answer 3

Temazepam
Lorazepam = 1-4mg daily, half in elderly for anxiety
1-2mg nocte for insomnia

12-24hrs

Indications
-Sleep onset and sleep maintenance
insomnia
o Anxiety disorders

Question 4

Give eg of long Acting benzo, duration, indication and dosing

Answer 4

Clonazepam = 1mg-2mg daily for anxiety
Diazepam = 2mg TDS, up to 15-30mg daily (half in elderly).

> 24 hours

Indications
o Anxiety
o Alcohol withdrawal syndrome
o Muscle relaxation
o Night terrors
o Acute paranoia episode

Question 5

Contraindication to benzo and drug interactions

Answer 5

o Pregnancy / breastfeeding – withdrawal sx in neonates
o Resp conditions (COPD / asthma / OSA -> respiratory depression)
o Neuromascular disease (MG)
o Narrow angle glaucoma

Contra-indicated:
o Opiates, Alcohol
o Barbiturates
P450

Question 6

what is the adverse effects of benzo

Answer 6

o Drowsiness / confusion / reduced concentration
o Transient amnesia / memory impairment
o Dizziness, Unsteadiness, weakness
o GI upset – change in appetite, N&V,
o Reduced libido / sexual dysfunction
o Hypotension
o Vision problems
o Suicide ideation

Question 7

what are the cautions in dosing for benzos

Answer 7

• Inform patients to avoid operating heavy machinery or driving after taking these

o Shouldn’t be used long term as can reduce effectiveness tolerance) and increase the risk of dependence/withdrawal, dementia, cognitive impairment.

o Abrupt reduction in dose / stopping can lead to either
- Rebound phenomena (return of previous sx but worse)
- Withdrawal - sweating/tremor/N&V/seizure/ insomnia/ anxiety/panic attack/psychosis can last months

Question 8

What is the treatment for withdrawal and overdose of benzo . what are symptoms of benzo overdose

Answer 8

Withdrawal
Treat: Give 5-20mg diazepam + seizure prophylaxis (carbamazepine) + antipsychotics

o Overdose = ataxia, hypotonia, hypotension, respiratory depression, coma. May be fatal.

• Treat: vomiting within an hour if conscious / gastric lavage / activated charcoal + ABC
• Antidote: flumazenil (in benzo naïve patients)