Anticonvulsants and anxiolytics: Barbiturates Flashcards
What is the major MOA of Barbiturates ?
They enhance the effect of GABA by stimulating its post-synaptic receptors.
What is the effect of the GABArgic transmission ?
It hyperpoloarizes the post synaptic neuronal membrane by modulating Cl- conductance properties.
What are the common medications in the Barbiturates class ?
Amobarbital, Butabarbital, Methohexital, Pentobarbital, Primidone, Phenobarbital and Thiopental.
How does Barbiturates work ?
They work by acting on alpha and beta subunits of GABA-A receptors. At lower doses barbiturates enhance the gabergic transmission by increasing the duration of the Cl- channel opening. At higher doses barbiturates mimic the effect of GABA even without GABA. In addition, these drugs also block the post synaptic AMPA receptors which reduce glutametergic transmission and inhibit the activation of Ca2+ channels in the pre-synaptic neurones leading to the inhibition of glutamate release.
What are the dose dependent effects of barbiturates ?
Low= Sedation, disinhibition and anxiolysis.
Medium= hypnosis and anaesthesia
high= medullary depression and coma.
How does barbiturates cause neuronal cell death at higher doses?
At higher doses they disrupt electron transport chain responsible for ATP production which leads to cell death.
what are the medications affected by barbiturate induced CYP450 induction?
Benzodiazepams, phenytoin, qunidine, and warfarin.
What is the first line treatment of for neonatal convulsions ?
Phenobarbital.
What are the clinical indications for Barbiturates ?
- Epileptic seizures and acute anxiety.
- Preoperative sedation to induce anaesthesia.
- Hypnotic induction
- Induced coma.
What are the side effects of Barbiturates ?
- Drowsiness, reduced concentration, problem solving ability and reaction time.
- Fast speech, excitement and restlessness due to paradoxical CNS stimulation.
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What are the complications of barbiturate overdose ?
Respiratory depression, cardiovascular collapse, coma and death.
Barbiturate overdose ____ treated with Flumazinil.
can’t be
What is the antedot for barbiturate overdose ?
Sodium bicarbonate.
What is the contraindication for barbiturates ?
- Acute intermittent prophyria
- severe cardiac or liver disease.
- Pregnancy and breast feeding.
Link to osmosis barbiturates
https://www.osmosis.org/learn/Anticonvulsants_and_anxiolytics:_Barbiturates?from=/pa/foundational-sciences/pharmacology-and-pharmacotherapeutics/neurologic-system/anticonvulsants
