POISONS: BENZODIAZEPINES

Question 1

BENZODIAZEPINES: INDICATIONS

Answer 1

• 1st line management for seizures, status epilepticus, alcohol withdrawl rxns
• Common choice sedation interventional procedures (if gen anaesthetic unsuitable)
• ST tx = anxiety, insomnia

Question 2

BENZODIAZEPINES: MOA

Answer 2

• Target is y-aminobutyric acid type A (GABA-A)
• GABA-A receptor is a chloride channel that opens in response to binding with GABA
• Opening the channel allows chloride to flow into the cell, cell more resistant to depolarisation
• BENZOD’s facilitate and enhance binding of GABA to the GABA-A receptor
• Widespread depressant effect on synaptic transmission
• Clinical manifestations = Reduced anxiety, sleepiness, sedation and anticonvulsive effects
• Ethanol also acts on the GABA receptor and in chronic excessive use the patient becomes tolerant to its presence
• Abrupt cessation = provokes the excitatory state of alcohol withdrawl

Question 3

BENZODIAZEPINES: ADVERSE EFFECTS

Answer 3

• Dose dependent drowsiness, sedation and coma
• Loss of AW reflexes can lead to AWO + Death
• Use for more than a few weeks = state of dependence can develop
• Abrupt cessation = a withdrawl rxn similar to alcohol withdrawl

Question 4

BENZODIAZEPINES: WARNINGS

Answer 4

• Elderly more susceptible to its effects
• Avoid in respiratory impairment patients or NMDx (myasthenia gravis)
• Avoid in Liver Failure = may precipitate HEPATIC ENCEPHALOPATHY

Question 5

BENZODIAZEPINES: INTERACTIONS

Answer 5

• The effects of benzodiazepines are additive to those of other sedating drugs, including alcohol and opioids
• Most depend on cytochrome P450 enzymes for elimination, so concurrent use with cytochrome P450 inhibitors (e.g. amiodarone, diltiazem, macrolides, fluconazole, protease inhibitors) may increase their effects.