How should medications be adjusted for a patient with severe impaired renal function (GFR of 18) taking NU-VALPROIC (Valproic acid), ASA (Aspirin), AG-ALLOPURINOL (Allopurinol), AG-FAMOTIDINE (Famotidine), SYNTHROID (Levothyroxine), VITAMIN D, OLANZAPINE, and CRESTOR (Rosuvastatin)?

Medication Adjustments for Severe Renal Impairment (GFR 18)

For a patient with severe renal impairment (GFR 18 ml/min/1.73m²), all medications should be reviewed and adjusted, with several requiring dose reductions or discontinuation to prevent toxicity and adverse effects.

General Principles for Medication Management in Severe CKD

The KDIGO guidelines emphasize that prescribers should take GFR into account when drug dosing 1. With a GFR of 18 ml/min/1.73m², this patient has Stage 4 CKD, requiring careful medication review and adjustment.

Medication-Specific Recommendations

1. NU-VALPROIC (Valproic acid) 250mg 2 tabs BID

   • No specific dose adjustment required
   • Monitor drug levels closely as free fraction may increase in renal failure
   • Watch for signs of toxicity despite normal total drug levels

2. ASA (Aspirin) 81mg 1 tab OD

   • Low-dose aspirin (81mg) can be continued
   • Monitor for increased bleeding risk
   • Avoid higher doses due to increased risk of bleeding and potential for worsening renal function

3. AG-ALLOPURINOL 100mg 1/2 tab daily

   • Reduce dose to 50mg daily (current dose appropriate)
   • Allopurinol requires significant dose reduction in renal impairment
   • High risk of severe hypersensitivity reactions with inappropriate dosing

4. AG-FAMOTIDINE 20mg one pill BID

   • Reduce to 20mg once daily
   • Famotidine is primarily eliminated by the kidneys
   • Accumulation can occur with normal dosing in severe renal impairment

5. SYNTHROID (Levothyroxine) 100mcg 1 tab OD

   • No dose adjustment required
   • Not significantly eliminated by the kidneys
   • Continue regular thyroid function monitoring

6. VITAMIN D 1000 IU daily

   • No dose adjustment required
   • Monitor calcium and phosphate levels
   • May need adjustment based on lab values rather than renal function

7. OLANZAPINE 10mg 1 tab BID

   • No specific dose adjustment required
   • Primarily metabolized by the liver
   • Start at lower doses in renal impairment if initiating therapy

8. CRESTOR (Rosuvastatin) 10mg 1 tab OD

   • Reduce to 5mg daily
   • Maximum recommended dose is 10mg daily in severe renal impairment
   • Higher risk of myopathy and rhabdomyolysis in renal impairment

Monitoring Recommendations

1. Regular renal function assessment

   • Check GFR, electrolytes every 3 months
   • More frequent monitoring during acute illness

2. Drug-specific monitoring

   • Valproic acid: Drug levels every 3-6 months
   • Allopurinol: Uric acid levels, watch for rash or hypersensitivity
   • Rosuvastatin: Liver enzymes, CK if muscle symptoms develop
   • Levothyroxine: TSH levels

3. Electrolyte monitoring

   • Potassium levels with multiple medications
   • Calcium and phosphate with vitamin D therapy

Important Precautions

• Temporary discontinuation during acute illness: Consider temporarily stopping potentially nephrotoxic medications during serious intercurrent illness 1, 2
• Avoid nephrotoxic combinations: The risk of nephrotoxicity increases significantly with multiple nephrotoxic agents 2
• Medication review: Have all medications (including OTC and supplements) reviewed by a pharmacist 1
• Hydration: Maintain adequate hydration, especially when using medications with potential nephrotoxicity
• Contrast procedures: If contrast studies are needed, use lowest possible dose and ensure adequate hydration 1

Common Pitfalls to Avoid

1. Overlooking renal dosing: Many medications require adjustment in CKD Stage 4
2. Relying on serum creatinine alone: GFR is more accurate for medication dosing
3. Failing to reassess: Renal function can worsen, requiring further dose adjustments
4. Not considering drug interactions: Multiple medications can interact, especially in renal impairment
5. Ignoring over-the-counter medications: These can contribute to nephrotoxicity and drug interactions

The patient should be advised to consult with a healthcare provider before using any over-the-counter medications or supplements, as these may further impair kidney function or interact with prescribed medications 1.