14 Questions
What is the consequence of taking high doses of benzodiazepines?
Coma and respiratory depression
What is the mechanism of action of benzodiazepines?
Bind to a BZ allosteric site and increase chloride channel opening
What is a characteristic of benzodiazepines compared to barbiturates?
They have a greater margin of safety
What is the effect of benzodiazepines on sleep patterns?
They reduce slow-wave sleep and REM sleep
What is a therapeutic use of benzodiazepines?
Short-term management of anxiety disorders
What is a characteristic of oxazepam, temazepam, and lorazepam?
They are metabolized by phase II conjugation
What is the mechanism of action of barbiturates?
They bind to an allosteric site on the GABA A receptor–chloride ion channel and increase the affinity of the receptor for GABA
What is the main therapeutic use of thiopental?
Short IV anesthetic in short procedures
What is a characteristic of barbiturates that distinguishes them from benzodiazepines?
They have a GABA-mimic action
What is a contraindication for the use of barbiturates?
Acute intermittent porphyria
What is a side effect of barbiturates?
Rebound insomnia after discontinuation
What is the classification of phenobarbitone?
Long acting
What is the use of phenobarbital in neonates?
Treatment of hyperbilirubinemia
Why are barbiturates limited in their therapeutic use?
Due to their strong sedative effects
Study Notes
Sedatives, Hypnotics, and CNS Stimulants
Barbiturates
- Classification: Ultrashort acting (Thiopental), Short acting (Pentobarbitone), Long acting (Phenobarbitone)
- Mechanism of Action: Bind to an allosteric site on the GABA A receptor–chloride ion channel, increasing the affinity of the receptor for GABA, opening chloride channel, and enhancing hyperpolarization of neurons
- Therapeutic uses:
- Anesthesia: Thiopental is used as a short IV anesthetic in short procedures
- Anticonvulsant: Phenobarbital is used in the treatment of grand mal epilepsy
- Neonatal jaundice: Phenobarbital is used in the treatment of hyperbilirubinemia in neonates (physiological jaundice)
- Adverse effects:
- Tolerance and dependence
- Sedation and hangover effect
- Rebound insomnia after discontinuation
- Induce the rate-limiting enzyme in porphyrin biosynthesis, making them contraindicated in acute intermittent porphyria
- Acute poisoning may occur at high doses, leading to coma and respiratory depression
- Drug interactions: Microsomal enzyme inducers
Benzodiazepines
- Classification: Short acting (Triazolam, Midazolam), Intermediate acting (Temazepam, Lorazepam, Oxazepam), Long acting (Diazepam, Clonazepam)
- Mechanism of Action: Bind to a BZ allosteric site, facilitating GABA binding and increasing the frequency of chloride channel opening, leading to neuronal membrane hyperpolarization
- Characteristics:
- Great margin of safety compared to barbiturates
- Can produce anterograde amnesia, useful for stressful procedures
- Reduce slow-wave sleep and REM sleep, disrupting sleep patterns
- Pharmacokinetics:
- Oxazepam, Temazepam, and Lorazepam are metabolized only by phase II conjugation, making them safer for elderly patients
- Therapeutic uses:
- Anxiety disorders: effective for short-term management
This quiz covers the classification and characteristics of sedatives, hypnotics, and CNS stimulants, including barbiturates, their uses, and effects.
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