Nokea
A patient has a drug level of 50 units/mL and the drug's half-life is 1 hour. If concentrations above 25 units/mL are considered toxic and no more drug is given, how long will it take for the blood level to reach the nontoxic range?
- A. 30 minutes
- B. 1 hour
- C. 2 hours
- D. 3 hours
Correct Answer: C
Rationale: Half-life is the time required for the serum concentration of a drug to decrease by 50%. After 1 hour, the serum concentration would be 25 units/mL (50/2). After 2 hours, the serum concentration would be 12.5 units/mL (25/2) and reach the nontoxic range.
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The patient has a diagnosis of multiple sclerosis and is taking the drug interferon beta-1a (Rebif). The patient takes this drug by subcutaneous injection three times a week. The dosage is 44 mcg per injection. If the patient takes an injection on Monday, how much of the drug would still be in the patient's system when she takes her next injection on Wednesday, assuming the half-life of the drug is 24 hours?
- A. 22 mcg
- B. 16.5 mcg
- C. 11 mcg
- D. 5.5 mcg
Correct Answer: C
Rationale: The half-life of a drug is the time it takes for the amount of drug in the body to decrease to 1 half the peak level it previously achieved. On Tuesday, there would be 22 mcg remaining in the body, so option A is incorrect. On Wednesday 11 mcg would remain, so option C is the correct answer. At 12 hours before taking the next dose on Wednesday, there would be 16.5 mcg remaining. If the injection were not taken on Wednesday, 12 hours after the dose was due, there would be 5.5 mcg remaining.
After teaching a group of nursing students about pharmacokinetics, the instructor determines that the teaching was successful when the students identify which of the following as the site for the metabolism of most drugs?
- A. Liver
- B. Lungs
- C. Kidneys
- D. Intestinal mucosa
Correct Answer: A
Rationale: Although the kidneys, lungs, plasma, and intestinal mucosa may aid in the metabolism of drugs, most drugs are metabolized by the liver.
A drug may be classified by which of the following? Select one that does not apply.
- A. The chemical type of the drug's active ingredient
- B. The way the drug is seen
- C. The generic name of the drug
- D. The trade name of the drug
Correct Answer: A
Rationale: A drug may be classified by the chemical type of the active ingredient or by the way it is used to treat a particular condition. Generic, trade, and nonproprietary refer to how a drug is named.
Jim presents with complaints of 'heartburn' that is minimally relieved with Tums (calcium carbonate) and is diagnosed with gastroesophageal reflux disease (GERD). An appropriate first-step therapy would be:
- A. Omeprazole (Prilosec) twice a day
- B. Ranitidine (Zantac) twice a day
- C. Famotidine (Pepcid) once a day
- D. Metoclopramide (Reglan) four times a day
Correct Answer: B
Rationale: Ranitidine , an H2 blocker, is a standard first-line GERD treatment; PPIs are next-step, and metoclopramide is for motility.
In which type of cell are ligand-gated ion channels most commonly found?
- A. Cells that are terminally differentiated
- B. Cells that produce large proteins
- C. Cells that need to respond quickly to external stimuli
- D. Cells that respond to mechanic forces
Correct Answer: C
Rationale: Ligand-gated ion channels enable rapid responses to stimuli, common in excitable cells like neurons and muscle cells.