ATI RN
Practice ATI B Exam Pharmacology Questions
Question 1 of 5
A male patient is undergoing chemotherapy may also be given the drug allopurinol (Zyloprim, Aloprim). Allopurinol inhibits the synthesis of uric acid. Concomitant administration of allopurinol prevents:
Correct Answer: B
Rationale: Allopurinol is primarily used to prevent gout and hyperuricemia, which are common side effects of chemotherapy. Chemotherapy often leads to the rapid destruction of cancer cells, releasing large amounts of uric acid into the bloodstream. This can cause hyperuricemia, leading to gout or kidney stones. Allopurinol works by inhibiting xanthine oxidase, an enzyme involved in uric acid production, thereby reducing uric acid levels. While myelosuppression and pancytopenia are concerns during chemotherapy, they are not directly addressed by allopurinol. Similarly, allopurinol does not inhibit cancer cell growth or replication.
Question 2 of 5
An 80-year-old man is taking digoxin and warfarin because of longstanding atrial fibrillation. He has an indwelling urinary catheter in situ, whilst awaiting a prostatectomy. At his pre-operation assessment he has a ventricular rate of 120/minute. The house officer doubles his daily digoxin dose and the operation is delayed one week. One week later he returns with nausea, vomiting, diarrhoea, abdominal pain, confusion, delirium and visual disturbances. The most likely cause of his current symptoms is:
Correct Answer: D
Rationale: Symptoms (nausea, confusion, visual changes) suggest digoxin toxicity, common in the elderly with doubled doses. Digoxin's narrow therapeutic index (0.5-2 ng/mL) and renal clearance (impaired with age) increase risk. Viral infection lacks cardiac specificity here. Hyperkalemia (e.g., >5.5 mmol/L) isn't indicated without ECG changes. Warfarin's INR prolongation causes bleeding, not these symptoms. UTI fits the catheter but not delirium/visual issues. Digoxin toxicity, from overdose and accumulation, explains the presentation, requiring level checks and cessation.
Question 3 of 5
Regarding phenytoin, all the following are true EXCEPT:
Correct Answer: B
Rationale: Phenytoin's oral bioavailability varies due to formulation and absorption, a true statement. It's highly plasma protein-bound (~90%), not poorly, making that false and the exception. Hepatic enzyme inducers (e.g., rifampicin) enhance its metabolism, true. At higher doses, its elimination shifts to zero-order due to saturated metabolism, true. Half-life ranges from 12-36 hours, also true. High protein binding affects free drug levels, critical for therapeutic monitoring, especially in hypoalbuminemia.
Question 4 of 5
The nurse plans medication education for a client who receives a prescription for sildenafil (Viagra). What will the best plan by the nurse include?
Correct Answer: C
Rationale: Sildenafil (Viagra), a phosphodiesterase-5 inhibitor, has a dosing limit of one pill per 24 hours to avoid risks like prolonged erections or hypotension, a key safety point for education. Grapefruit juice increases sildenafil levels by inhibiting metabolism, not decreasing effects, risking intensified side effects. It's optimally taken 1 hour before sex, effective up to 4 hours-not 6-setting realistic timing expectations. Food, especially high-fat meals, delays absorption, so it's best on an empty stomach. The 24-hour limit ensures safe use, balancing efficacy with minimizing adverse effects, aligning with prescribing standards and making it the priority in client teaching.
Question 5 of 5
Prior to administering medications, the student nurse reviews the therapeutic index. Which statement best describes the student's understanding of therapeutic index?
Correct Answer: B
Rationale: Therapeutic index (TI), the ratio of toxic to effective dose, gauges safety-wide TI means safer dosing, helping the student assess if doses are within safe limits. Best drug choice is clinical, not TI-based. Interactions aren't TI-specific. Monitoring needs tie to narrow TI drugs (e.g., lithium), but safety is broader. TI ensures safe dosing, a key review point.