Benzodiazepines Flashcards
What are benzodiazepines and where does the name come from?
Sedative hypnotic drugs that are so called because they’re composed of a benzene ring with 7-member diazepine moiety, and various side chains that affect potency, duration of activity, metabolite activity, and elimination rate.
What were the first benzos?
Chlordiazepoxide (Librium) discovered in 1954, in clinical use by the 1960s. Diazepam (Valium) followed in 1963.
What are they used for?
BZDs are used for sedation and to treat anxiety, seizures, withdrawal states, insomnia, and drug-associated agitation. They are frequently combined with other medications for procedural sedation.
How do they work at the molecular level?
BZDs exert their effect via modulation of the gamma-aminobutyric acid A (GABA-A) receptor. GABA is the chief inhibitory neurotransmitter of the central nervous system; they don’t alter the synthesis, release, or metabolism of GABA but rather potentiate its inhibitory actions by augmenting receptor binding which increases the flow of chloride ions through the GABA ion channel, causing postsynaptic hyperpolarization and a decreased ability to initiate an action potential.
True or false: In overdose, vital signs are often normal.
True. People can be very sedated, slurring speech, etc, and have normal vitals.
What are some symptoms of BZD withdrawal?
tremors, anxiety, perceptual disturbances, dysphoria, psychosis, and seizures
What is flumazenil?
nonspecific competitive antagonist for BZD receptor; can precipitate withdrawal szr in pt’s with tolerance; wise to call toxicologist or poison control before making the decision to use it
What can you use to BZD withdrawal?
Benzos, usually longer half-life ones like diazepam (especially if you’re doing it IV) and chlordiazepoxide. Some evidence of benefit with carbamazepine, less for VPA, but both are sometimes used.
T/F: Oral BZDs taken without a coingestant, rarely cause significant toxicity?
True. People will get sleepy, but it usually not fatal. Dangerous doses (from respiratory depression standpoint) are hard to quantify because it depends on tolerance, weight, age, coningestants, and genetics; and if it’s truly just benzos on board, it’s rare to see respiratory depression apparently due to the low density of binding sites in the brainstem respiratory center
How do people with BZD overdose present?
Like they’re drunk. AMS (usually depressed), slurred speech, ataxia,
How does the most commonly used urine test for BZD work?
It detects the 1,4 benzodiazepine metabolites, so it may not dectect clonazepam, lorazepam, midazolam, or alprazolam. Sometimes can be detected as early as 3 hours after ingestion, and up to 2 weeks after.
T/F BZD levels are clinically useful in the setting of suspected overdose.
False. You can’t get them most places, and even if you can, they don’t correlate well with the clinical symptoms and are thus not very useful.
What other studies might you consider in suspected BZD overdose, in addition to standard screening labs like CMP, CBC?
Get a finger stick glucose immediately. Get acetaminophen and salicylate levels as this is a common coingestant. ECG. Also get a pregnancy test in women of childbearing age. Also reasonable to get a BAL as ethanol is a common coingestant.
When might you consider using activated charcoal in suspected BZD overdose?
If you’re worried about a possible coingestant and the patient is able to protect their airway (or is intubated). Not recommended to use charcoal or whole bowel irrigation if BZD is the only suspected agent.
How long do patients need to be observed after an isolated BZD ingestion prior to going to inpatient psychiatry (assuming it’s indicated)?
4-6 hours assuming sedation has resolved. Pt needs to be able to walk. If they’re still obtunded after 6 hours, they need to be admitted to a different service.
