Chapter 13: Benzodiazepines and Barbiturates Flashcards
What type of drug is Phenobarbital?
A barbiturate.
What is the mechanism of action for benzodiazepines?
Benzodiazepines facilitate the binding of GABA to its receptor. They do not directly stimulate the GABA receptor; rather they bind to a site adjacent to the GABA receptor, producing a 3D shape change in the receptor that, in turn, increases the affinity of GABA for the receptor. That action increases the inhibitory synaptic action of GABA, facilitating the influx of chloride ions, causing hyper-polarization of the post synaptic neuron and depressing its excitability.
Where do Benzodiazepines exert their anxiolytic properties?
On GABA neurons at limbic centers. Their actions at other regions (for ex. The cerebral cortex and Brain stem) produce side effects such as sedation, cognitive impairment, amnesia, and muscle relaxation.
How are barbiturates absorbed?
Absorbed orally and well distributed to most body tissues. Short acting ones are lipid soluble and cross the blood brain barrier.
What neural structures are involved in fear?
Amygdala, orbital-frontal cortex, and the insula.
What is a “black-out?”
A state of retroactive amnesia. More specifically it is a state of drug-induced, reversible, organic brain syndrome (or state of amnesia). Loss of memory for new events or actions until blood level of drug falls.
What is Chloral hydrate?
A sedative-hypnotic. It breaks down into ethyl alcohol.
What are some medical uses for Barbiturates?
Anti-convulsants, anesthetics, provide brain protection after injury, death-inducing agents.
What are some problems with Barbiturates?
Lethal in overdose, narrow therapeutic-to-toxic range, high potential for abuse, have dangerous drug interactions.
What is the mechanism of action for barbiturates? What about at high doses?
Facilitate GABA activity by increasing the duration of the chloride channel openings caused by GABA (GABA receptor is a chloride channel). It can also depress actions of Glutamate and have impacts at cell membranes. At high doses, it may open the channel even without GABA.
