MTM Drug Therapy Monitoring & Clinical Decision-Making 4 — Questions and Answers
Question 1: A patient with COPD and atrial fibrillation is prescribed theophylline. Which newly added medication would MOST increase the risk of theophylline toxicity?
- Ciprofloxacin (Correct answer)
- Prednisone
- Albuterol inhaler
- Tiotropium
Correct answer: Ciprofloxacin
Ciprofloxacin is a potent CYP1A2 inhibitor that can increase theophylline concentrations by 30-50%, leading to toxicity including seizures and arrhythmias.
Question 2: In monitoring a patient on methotrexate for rheumatoid arthritis, which laboratory finding most directly signals hepatotoxicity?
- Elevated serum creatinine
- AST/ALT >3× upper limit of normal on two consecutive tests (Correct answer)
- Low serum albumin <3.5 g/dL
- Platelet count <100,000/mm³
Correct answer: AST/ALT >3× upper limit of normal on two consecutive tests
Persistently elevated transaminases (>3× ULN on two tests 4-6 weeks apart) are the primary signal for methotrexate hepatotoxicity requiring dose reduction or discontinuation.
Question 3: A patient with chronic stable angina on amlodipine 5 mg reports continued chest pain with exertion. HR is 68 bpm and BP is 145/88 mmHg. What is the most appropriate clinical decision?
- Add long-acting nitrate (isosorbide mononitrate)
- Increase amlodipine to 10 mg
- Add metoprolol succinate and titrate to HR 55-60 bpm (Correct answer)
- Switch amlodipine to diltiazem
Correct answer: Add metoprolol succinate and titrate to HR 55-60 bpm
Adding a beta-blocker to reduce heart rate to 55-60 bpm addresses both uncontrolled angina and elevated blood pressure, following ACC/AHA angina guidelines.
Question 4: Which finding on a medication therapy review would MOST appropriately trigger a recommendation to decrease a medication dose rather than add a new drug?
- A1C of 9.5% on metformin monotherapy
- Blood pressure 155/95 mmHg on lisinopril 10 mg
- INR of 6.2 on warfarin 5 mg daily with no bleeding (Correct answer)
- LDL-C of 95 mg/dL on atorvastatin 40 mg
Correct answer: INR of 6.2 on warfarin 5 mg daily with no bleeding
A supratherapeutic INR of 6.2 requires warfarin dose reduction, not addition of another drug, to bring anticoagulation back into therapeutic range.
Question 5: A patient on digoxin for heart failure with reduced ejection fraction has a level of 1.8 ng/mL. The patient reports nausea and sees yellow halos. What is the most important next step?
- Recheck digoxin level in 24 hours before making changes
- Hold digoxin and check electrolytes, particularly potassium (Correct answer)
- Reduce digoxin dose by 50% and continue therapy
- Add an antiemetic to manage GI symptoms
Correct answer: Hold digoxin and check electrolytes, particularly potassium
Digoxin toxicity symptoms (GI symptoms, visual disturbances) require immediate drug hold and electrolyte assessment since hypokalemia potentiates toxicity.
Question 6: Which clinical scenario best represents a drug therapy problem of 'unnecessary drug therapy' in an MTM encounter?
- A patient on aspirin 81 mg for primary prevention who is 45 years old with 8% 10-year ASCVD risk (Correct answer)
- A patient on amlodipine with uncontrolled BP needing a second agent
- A patient on metformin with A1C of 11% requiring insulin add-on
- A patient on lisinopril post-MI with EF of 40%
Correct answer: A patient on aspirin 81 mg for primary prevention who is 45 years old with 8% 10-year ASCVD risk
Current USPSTF guidelines recommend against initiating aspirin for primary prevention in adults ≥60 years, and the benefit-risk balance is unfavorable at 8% ASCVD risk in younger patients without established CVD.
Question 7: During therapeutic drug monitoring for aminoglycosides using extended-interval dosing (once-daily), what is the primary parameter used to guide dosing adjustments?
- Peak concentration drawn 30 minutes after infusion
- Trough concentration drawn just before next dose
- 6-hour post-dose level plotted on a Hartford nomogram (Correct answer)
- AUC calculated from two drug levels
Correct answer: 6-hour post-dose level plotted on a Hartford nomogram
The Hartford nomogram uses a single drug level drawn 6-14 hours post-dose to determine the appropriate dosing interval for extended-interval aminoglycoside therapy.
MTM Drug Therapy Monitoring & Clinical Decision-Making 4
A patient with COPD and atrial fibrillation is prescribed theophylline.
Which newly added medication would MOST increase the risk of theophylline toxicity?