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The administration of which of the following drugs is most likely to result in sensitization?
Cocaine and amphetamines are the drugs most likely to cause sensitization. It is poorly studied in humans, but it is thought that stimulant psychosis results from sensitization after prolonged use.
Which of the following is an example of learned tolerance?
Learned tolerance refers to the reduction of the effect of a drug due to compensatory mechanisms that are learned. An example is walking a straight line despite the motor impairment caused by alcohol. This likely represents both acquisition of motor skills and the learned awareness of one’s deficit; thus the person walks more carefully.
Three teenaged high school students develop meningitis. A classmate is concerned and comes to see you. Which of the following is the most appropriate next step in management?
This is likely an outbreak of meningitis secondary to Neisseria meningitidis. The first line of drugs used for treatment of acute disease includes cefixime, levofloxacin, and ceftriaxone. For prophylaxis, rifampin is the preferred agent.
A 69-year-old man’s dyspepsia is improved with ranitidine therapy. Which of the following is the best explanation for improvement in his symptoms?
Ranitidine blocks histamine-H2 to receptors and is well-absorbed in the small intestine. It decreases all gastric secretion, not just acid, and is helpful in short bowel syndromes, whereas omeprazole is not.
Which of the following is the most deleterious effect of epinephrine infusion on cardiac function?
All the changes listed are correct, but the increased automaticity of the heart with the development of ventricular premature beats (or more serious ventricular arrhythmias) is the most prominent change.
Which of the following features of barbiturateinduced coma is most likely correct?
Most deaths from barbiturate-induced coma are caused by pulmonary complications (atelectasis, edema, bronchopneumonia) or renal failure. Hypoventilation is characteristic, and only 10 times the full reactive dose can cause severe poisoning. This low toxic-therapeutic ratio is one reason why barbiturate use (hence barbiturate coma) is declining.
A 68-year-old man presents with symptoms and signs of CHF. Which of the following is a contraindication to use furosemide?
Furosemide is effective despite gross electrolyte disturbances or hypoalbuminemia. Excretion of large volumes of bicarbonate-poor urine leads to alkalosis, so an acidosis is not a contradiction in severe fluid and electrolyte depletion; a trial in oliguric states is often appropriate. Furosemide is related to sulfonamide, and severe allergic reactions can occur.
Which of the following is a symptom of withdrawal from prolonged moderate dose benzodiazepine usage?
Muscle cramps, anxiety, insomnia, and dizziness are among the common side effects of withdrawal from moderate dose usage. Withdrawal seizures and delirium occur usually in withdrawal from high dosage. Withdrawal should be done gradually, often over many months.
Which of the following is the most likely reason why fentanyl does not disturb cardiovascular stability as much as morphine?
Morphine releases histamine and can cause cardiovascular instability. Fentanyl does not release histamine, and causes only mild decreases in heart rate and blood pressure. Fentanyl, a lipid-soluble drug, has an elimination half-life between 3 and 4 hours. It is 100 times more potent than morphine.
A43-year-old woman with breast cancer is being treated with doxorubicin. Which of the following is a limitation to therapy with doxorubicin?
Anthracyclines include daunorubicin and doxorubicin. The major site of metabolism is the liver, and the mechanism of action includes inhibition of deoxyribonucleic acid (DNA)-dependent ribonucleic acid (RNA) metabolism. The cardiomyopathy is characteristic of these drugs and is characterized by arrhythmias and cumulative dose-related CHF.
A 69-year-old man with heart failure and paroxysmal atrial fibrillation is prescribed amiodarone for maintenance of sinus rhythm. Which of the following is a known characteristic of amiodarone?
With prolonged treatment, the active Ndesethyl derivative of amiodarone accumulates in plasma, and its concentration may exceed that of the parent compound. Amiodarone is poorly (approximately 30%) absorbed and there is marked interindividual variability. The half-life is long, 25–60 days, presumably because it is extensively bound to tissues, resulting in a large volume of distribution and a reservoir of drug.
Which of the following best describes sensitization to a drug?
Sensitization is the reverse of tolerance. It refers to an increase in effect of the drug with repetition of the same dose. It does not occur during an acute binge. The dose response curve would be shifted to the left.
A 23-year-old homeless man is found to have consumed alcohol adulterated with methanol. He is started on treatment effective for minimizing the toxicity to methanol. Which of the following is the most likely explanation for the benefit of this treatment?
Ethanol is the standard antidote for methanol. It inhibits the conversion of methanol to its toxic metabolite, formic acid, by alcohol dehydrogenase.
Which of the following features concerning heroin withdrawal is correct?
Craving for opioids, restlessness, irritability, and anxiety are common symptoms of heroin withdrawal. Piloerection, pupillary dilatation, sweating, tachycardia, and blood pressure elevation are frequently seen signs of heroin withdrawal. It starts within 6–12 hours of the last dose and is quite unpleasant, but not life-threatening.
Which of the following opioid analgesics is most likely to cause central nervous system (CNS) disturbance?
Meperidine has a half-life of 3 hours, but it has an active metabolite, normeperidine, which has a half-life of 15–20 hours. Therefore, accumulation of normeperidine with toxicity is common. The drug should not be used for prolonged periods (over 48 hours), and probably should not be used at all in those susceptible to delirium (e.g., the elderly).
Which of the following is a stimulus for insulin secretion?
Ketones, glucose amino acids, and fatty acids promote insulin secretion. Stimulation of alpha2-adrenergic receptors inhibits insulin secretion, whereas beta2-adrenergic receptor stimulation enhances release of insulin. As a result, beta2-adrenergic receptor antagonists decrease insulin levels. Activation of the autonomic nervous system (hypoxia, hypothermia, severe burns, surgery) will also suppress insulin secretion.
Which of the following statements concerning the use of isoproterenol and dobutamine for shock is correct?
The preferential effect of dobutamine on contractility makes it useful in low cardiac output states. Both drugs are very short-acting, can potentiate cardiac ischemia, and affect smooth muscle. Unlike isoproterenol, dobutamine frequently increases blood pressure quite significantly thus requiring dosage adjustment
Which of the following is the most striking difference in the cardiac actions of epinephrine and norepinephrine?
Epinephrine results in a more rapid heart rate and more powerful systolic contraction resulting in increased cardiac output. Norepinephrine results in an unchanged or even decreased cardiac output.
Which of the following is the most likely reason for pharmacokinetic tolerance?
The most common cause of pharmacokinetic tolerance is an increase in the metabolism of the drug. Since these same enzymes can then metabolize other drugs, this kind of tolerance is not necessarily specific to the drug that induced it.
Which of the following statements concerning innate tolerance to alcohol is correct?
It is felt that innate tolerance is a polygenic characteristic. Frequently, variation in pharmacokinetic variables (absorption, metabolism, excretion), which can be inherited, are the cause of different levels of innate tolerance. Those who have high levels of innate tolerance are more likely to become addicted to alcohol. There is a higher concordance rate for alcoholism among identical twins than fraternal twins, but it is not 100%.
Which of the following is the most likely reason why beta2-selective adrenergic agonists are preferred to nonselective beta-adrenergic agonists in the treatment of asthma?
Most of the side effects from the use of betaadrenergic agonists in asthma come from stimulation of the beta1-receptors in the heart. Thus, beta2-selective agonists, which act primarily in the lung, are safer to use. Both selective and nonselective beta-agonists will decrease airway resistance. This is their major therapeutic effect. The effects on mucociliary transit, mast cells, and microvascular permeability occur with both nonselective and selective agonists, but the clinical importance of these effects is unclear.
Which of the following statements concerning the relative effects of epinephrine and norepinephrine infusion on peripheral circulation is correct?
Both epinephrine and norepinephrine decrease renal blood flow. Epinephrine decreases total peripheral resistance whereas norepinephrine increases total peripheral resistance. Both drugs decrease cutaneous blood flow and only epinephrine increases muscle blood flow.
Which of the following drugs is most likely to result in addiction among those who have ever used it?
Almost one-third of people who have tried tobacco become addicted. In comparison, about 15% become addicted to alcohol. Heroin is also highly addictive (23% of users become addicted), but since so few people even try heroin, the addiction rate in society as a whole is quite low (0.4%).