What adjustments should be made to a 92-year-old patient's medication regimen, consisting of metoprolol (25 mg qd), amlodipine (10 mg qd), furosemide (20 mg qd), and losartan (100 mg qd), given her impaired renal function?

Medication Adjustments for a 92-Year-Old Patient with Reduced Renal Function

The losartan dose should be reduced from 100 mg to 25-50 mg daily, and furosemide should be monitored closely with possible dose reduction to 10 mg daily due to the patient's advanced age and reduced renal function. 1, 2, 3

Current Medication Assessment

This 92-year-old patient is currently on:

• Metoprolol 25 mg daily
• Amlodipine 10 mg daily
• Furosemide 20 mg daily
• Losartan 100 mg daily

Losartan Adjustment

Losartan requires significant adjustment:

• Current dose (100 mg daily) is excessive for a 92-year-old with reduced renal function
• FDA labeling indicates no specific dose adjustment is necessary for renal impairment unless the patient is volume depleted 2
• However, geriatric clinical pharmacist consensus guidelines recommend caution with angiotensin receptor blockers in elderly patients with reduced renal function 1
• High risk of hyperkalemia, especially when combined with other medications affecting potassium levels 1

Recommendation: Reduce losartan to 25-50 mg daily

Furosemide Adjustment

Furosemide requires careful monitoring:

• Loop diuretics may have reduced effectiveness in elderly patients with decreased glomerular filtration 1
• Risk of electrolyte disturbances, dehydration, and worsening renal function 1
• Elderly patients are more likely to have decreased renal function, increasing risk of toxic reactions 3

Recommendation: Consider reducing to 10 mg daily with close monitoring of fluid status, electrolytes, and renal function

Metoprolol Assessment

Metoprolol appears appropriate:

• Current dose (25 mg daily) is already at the lower end of dosing range
• Metoprolol is primarily metabolized by the liver, not requiring dose adjustment for renal impairment 4
• FDA labeling recommends low initial doses in elderly patients due to potential decreased hepatic, renal, or cardiac function 4

Recommendation: Maintain current dose of 25 mg daily

Amlodipine Assessment

Amlodipine requires consideration:

• Current dose (10 mg daily) is at the maximum recommended dose
• Elderly patients may experience greater antihypertensive effects due to decreased baroreceptor response 1
• Risk of peripheral edema, hypotension, and falls in elderly patients 1

Recommendation: Consider reducing to 5 mg daily if blood pressure control allows

Monitoring Recommendations

1. Renal Function:

   • Monitor creatinine and estimated GFR regularly (every 1-3 months)
   • Calculate creatinine clearance using Cockcroft-Gault formula 5

2. Electrolytes:

   • Monitor potassium, sodium, and magnesium levels, especially with combined losartan and furosemide therapy
   • Risk of hyperkalemia with losartan and hypokalemia with furosemide 1

3. Blood Pressure:

   • Monitor for orthostatic hypotension
   • Target blood pressure should be individualized based on frailty 1

4. Hydration Status:

   • Assess for signs of dehydration or fluid overload
   • Adjust furosemide based on clinical status 1

Pitfalls to Avoid

1. Medication Interactions: The combination of losartan and furosemide can lead to significant electrolyte disturbances and hypotension 1

2. Renal Function Assessment: Serum creatinine alone may underestimate renal impairment in elderly patients due to decreased muscle mass 1, 6

3. Excessive Diuresis: Avoid aggressive diuresis which can worsen renal function and lead to electrolyte abnormalities 1, 7

4. Polypharmacy: This patient is on multiple antihypertensives which increases risk of adverse effects; simplify regimen when possible 1

5. Worsening Renal Function: Worsening renal function in elderly heart failure patients is associated with longer hospital stays and increased mortality 7

By making these adjustments, the risk of adverse drug reactions related to renal insufficiency can be significantly reduced while maintaining effective treatment of the patient's underlying conditions.