Chapter 9: Hypnotics, Sedatives, and Ethanol
A 43-year-old man with severe hepatic cirrhosis requires a sedative for insomnia. Which of the following sedatives would be the best choice for this patient?
Answer is c. The benzodiazepines are metabolized extensively by hepatic CYPs, particularly CYPs 3A4 and 2C19. Some benzodiazepines, such as oxazepam and lorazepam, are conjugated directly and are not metabolized by these enzymes. Thus, the benzodiazepine of choice in a patient who might have diminished hepatic metabolism by CYPs would be either oxazepam or lorazepam.
A 19-year-old college student has overdosed on phenobarbital. After standard supportive care, the physician in the ER should do which of the following to hasten the elimination of phenobarbital?
e. Use a drug to stimulate hepatic CYP 2C19
Answer is d. The treatment of acute barbiturate intoxication is based on general supportive measures, which are applicable in most respects to poisoning by any CNS depressant. Hemodialysis or hemoperfusion is necessary only rarely, and the use of CNS stimulants is contraindicated because they increase the mortality rate. If renal and cardiac functions are satisfactory, and the patient is hydrated, forced diuresis and alkalinization of the urine will hasten the excretion of phenobarbital. Measures to prevent or treat atelectasis should be taken, and mechanical ventilation should be initiated when indicated. See Chapter 3 Clinical and Environmental Toxicity.
A 32-year-old woman is taking ramelteon for chronic insomnia. Ramelteon binds to
a. melatonin receptors M1 and M2.
b. muscarinic receptors M3.
d. α1-adrenergic receptors.
e. D2 dopaminergic receptors.
Answer is a. Ramelteon is a synthetic tricyclic analog of melatonin. Binding of agonists, such as melatonin, to MT1 receptors promotes the onset of sleep while melatonin binding to MT2 receptors shifts the timing of the circadian system. Ramelteon binds to both MT1 and MT2 receptors with high affinity but, unlike melatonin, it does not bind appreciably to quinone reductase 2, the structurally unrelated ...