Pharmacology - Sedative-Hypnotic drugs
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- What is the GABAa receptor?
- a chloride channel
- What happens when the GABAa receptor is stimulated?
- the chloride channel opens, chloride enters the cell, and it becomes hyperpolarized
- Where do benzodiazepines (BDZs) bind?
- to an allosteric site on the GABAa receptor
- What is the effect of BDZ binding to the GABAa receptor?
- they increase the frequency of opening of the chloride channels, increasing the amplitude of the IPSP
- Which is safer: BDZs or barbiturates? Why?
- BDZs, they have fewer side effects (esp. respiratory depression)
- How are BDZs administered and where are they metabolized?
- orally; in the liver
- BDZs are dangerous when taken in combination with what?
- alcohol or other CNS depressants
- Sudden withdrawal of BDZs after prolonged use may cause what?
- SEIZURES and psychosis
- Which drugs decrease the metabolism of BDZs, thereby increasing their levels?
- cimetidine, disulfiram, ethanol, isoniazid, and valproic acid (also displaces BDZs from binding sites)
- Which drug decreases diazepam excretion?
- acetaminophen
- Which drugs decrease the absorption of BDZs, thereby decreasing their levels?
- antacids
- Which drugs increase the metabolism of BDZs?
- oral contraceptives
- Which BDZs are used to treat insomnia?
- triazolam (halcion), temazepam (restoril), and flurazepam
- Which BDZ is used to treat only anxiety?
- oxazepam
- Which BDZ is used to treat only panic disorders?
- alprazolam (xanax)
- Which BDZ is used for the treatment of anxiety, preanesthetic medication, and status epilepticus?
- lorazepam (ativan)
- Which BDZ is used for anesthesia and medical procedures?
- midazolam (versed)
- Which BDZ is used for the treatment of epilepsy and anxiety?
- clorazepate
- Which BDZ is used for the treatment of anxiety, skeletal muscle relaxation, preanesthetic medication, and status epilepticus?
- diazepam (valium)
- Which BDZ is used for ethanol withdrawal symptoms, anxiety, and preanesthetic medication?
- chlordiazepoxide
- On what does the CNS depressant action of barbiturates depend?
- their lipid solubility
- If a barbiturate has high lipid solubility, how does this affect its pharmacokinetics?
- it works faster, has decreased duration of action, increased metabolic degradation, and greater hypnotic effect
- How is the action of barbiturates terminated?
- physical redistribution to fat tissue, hepatic metabolism, and urinary excretion
- Which enzymes do barbiturates induce?
- hepatic microsomal enzymes
- How do barbiturates work?
- they bind to GABAa receptors, increasing the duration of the opening of the chloride channel
- What is the longest-acting barbiturate and what is its use?
- phenobarbital; it's an anticonvulsant
- What are the two ultra-short-acting barbiturates and what is their use?
- thiopental and methohexital; induction of anesthesia
- Sudden withdrawal of barbiturates after prolonged use may cause what dangerous side effects?
- SEIZURES, orthostatic hypotension, cardiovascular collapse
- What are the symptoms of barbiturate overdose?
- mild OD is like ethanol intoxication; severe OD can cause coma, shock, and hypothermia
- What are some side effects of barbiturates? (hint: there are a LOT; no one should take these!!)
- sedation, ataxia, respiratory depression, rash, angioedema, folate-responsive megaloblastic anemia, osteomalacia, acute intermittent porphyria
- When barbiturates induce microsomal enzymes, they increase the metabolism of what other drugs?
- phenytoin, steroid hormones, tricyclic antidepressants, oral anticoagulants, digoxin, quinidine, theophylline, and beta-blockers
- How does buspirone work?
- it's a partial agonist at 5HT1a receptors; it decreases serotonin
- What is different about the effects buspirone when compared to BDZs?
- buspirone has no muscle relaxant or anticonvulsant activity and doesn't increase the CNS depressant effect of ethanol
- How does zolpidem tartrate work?
-
It is a GABAa agonist (?)
it's BZ1 selective as opposed to BDZs, which interact with BZ1 and BZ2 - What is buspirone used for? Zolpidem tartrate?
- anxiety; short-term treatment of insomnia
- What is meprobamate used for?
- anxiety and sedation
- What is chloral hydrate used for?
- sleep inducer
- What are the side effects of chloral hydrate?
- irritation of mucous membranes and inhibition of ethanol metabolism
- What is glutethimide used for?
- sedation/hypnotic
- What are the side effects of glutethimide?
- anticholinergic effects
- Which drugs induce hepatic microsomal enzymes?
- barbiturates, meprobamate, glutethimide
- Phenobarbital has been used to treat what neonatal illness? Why?
- kernicterus and hyperbilirubinemia; it increases the elimination of bilirubin