What blood pressure medication changes are recommended for a patient with impaired renal function, taking losartan 50mg, and presenting with hypertension?

Management of Hypertension in a Patient with Impaired Renal Function

For a patient with decreasing renal function (Cr 1.6, GFR 46, BUN 22), currently on losartan 50mg with elevated BP (152/90), the recommended next step is to increase losartan to 100mg daily as this dose is more effective for both blood pressure control and renoprotection in patients with renal impairment.

Assessment of Current Situation

The patient presents with:

• Decreasing renal function (Cr 1.6, GFR 46, BUN 22) - Stage 3a CKD
• Current medication: losartan 50mg
• Inadequate BP control: 152/90 mmHg (Stage 2 hypertension)

Medication Adjustment Algorithm

Step 1: Optimize Current Therapy

• Increase losartan from 50mg to 100mg daily
  • This is supported by evidence showing that 100mg of losartan is more effective than 50mg for both BP reduction and renoprotection 1
  • Losartan is safe in patients with renal impairment without requiring dose adjustment unless the patient is volume depleted 2
  • The FDA label indicates that losartan can be increased to a maximum dose of 100mg once daily as needed to control blood pressure 2

Step 2: If BP Remains Uncontrolled After 4 Weeks

• Add a thiazide diuretic (if GFR remains >30 mL/min)
  • The ESC guidelines recommend RAS blockers (like losartan) combined with a diuretic for patients with CKD 3
  • The 2017 ACC/AHA guidelines recommend a combination of RAS blockers and thiazide diuretics for stage 2 hypertension 3

Step 3: If Further Medication Is Needed

• Add a calcium channel blocker (CCB) as a third agent
  • The ESC guidelines recommend a triple drug regimen of an ACE inhibitor/ARB, CCB, and thiazide diuretic 4

Rationale for Recommended Approach

1. Maximizing ARB Therapy First:

   • Research shows losartan 100mg provides significantly better albuminuria reduction (48%) compared to 50mg (30%) in patients with renal impairment 1
   • Losartan 100mg also provides better BP reduction than 50mg without increased adverse effects 5, 1

2. Safety in Renal Impairment:

   • Losartan is well-tolerated in patients with chronic renal insufficiency 6
   • No dose adjustment is necessary for patients with renal impairment unless they are volume depleted 2

3. Guideline Alignment:

   • For patients with CKD, the ESC guidelines recommend RAS blockers as part of the treatment strategy 3
   • The ACC/AHA guidelines recommend combination therapy for stage 2 hypertension 3

Monitoring Recommendations

• Check renal function and electrolytes within 1-2 weeks after increasing losartan dose 4
• Monitor for hyperkalemia, especially with increased dosage of RAS blockers 3
• Schedule follow-up BP measurement in 4 weeks to assess response 3

Important Considerations and Pitfalls

• Hyperkalemia Risk: Monitor potassium levels closely, especially with higher doses of losartan in the setting of renal impairment
• Volume Status: Ensure patient is not volume depleted before increasing losartan dose
• Loop Diuretics: If GFR decreases to <30 mL/min, consider switching from thiazide to loop diuretics 4
• Medication Adherence: Assess adherence to current therapy before making changes
• Avoid NSAIDs: These can worsen both BP control and renal function 4

By following this approach, you should achieve better BP control while providing renoprotection for this patient with impaired renal function.