Benzos + Z-Drugs Flashcards
What are the three unusual but eminently treatable causes for coma?
Carbamazepine, sodium valproate and barbiturates poisoning
How common is benzo overdose in the context of deliberate self-poisonings?
Involved in up to 1/3
Overdose of what benzo is the most commonly associated with the greastest risk of CNS depression?
Alprazolam
When zolpiclone/zolpidem are taken on their own, what is the most likely clinical scenario?
Rarely cause severe CNS/respiratory depression when taken alone
What is the mechanism of action of benzodiazepines?
Enhancing GABA-mediate neurotransmission, bind to GABA-A receptor complex and increase the FREQUENCY of chloride channel opening
How do zolpidem and zolpiclone work?
Non-benzo sedative-hypnotics that also act at the GABA-A receptor complex.
Describe the pharmacokinetics of benzos.
Rapid oral absorption, highly protein bound, VoD of 0.5-4 L/kg. Undergo hepatic metabolism with many active metabolites.
What does the duration of effect depend on with a benzo overdose?
CNS tolerance and redistribution rather than elimination
Describe the clinical features of benzo overdose.
Onset 1-2 hours - ataxia, lethargy, slurred speech, drowsiness. Profound coma rarely (apart from mixed ingestions/alprazolam). Apnoea/airway obstruction. In large ingestions: hypothermia, bradycardia, hypotension. Symptoms resolve in 12 hours (longer in elderly).
What is flumazenil?
It is a competitive benzo antagonist with a limited role in benzo overdoses.
Discuss the indications for flumazenil.
(1) Mx of airway/breathing when resources are not available to safely intubate/ventilate the patient, (2) Diagnostic tool, (3) Reversal of conscious sedation
What are the primary concerns with flumazenil in benzo overdoses.
If patients are at risk of seizures you are then unable to give them benzos to stop them. Seizures due to co-ingestions but also as a result of benzo withdrawal.
