What medication needs a dose adjustment in a 74-year-old male with Hypertension (HTN), paroxysmal atrial fibrillation (a fib), stage 2 Chronic Kidney Disease (CKD) and impaired renal function, taking losartan (Angiotensin II receptor antagonist), apixaban (Factor Xa inhibitor), metoprolol (Beta blocker) and morphine, also hydrocodone/acetaminophen as needed?

Apixaban Requires Dose Adjustment Due to Declining Renal Function

Based on the patient's worsening renal function with creatinine increase from 1.5 to 2.1, apixaban (Eliquis) requires dose adjustment.

Assessment of Renal Function

• The patient is a 74-year-old male with:
  • Hypertension, paroxysmal atrial fibrillation, stage 2 CKD, and chronic back pain
  • Current medications: losartan, apixaban, metoprolol, morphine, and hydrocodone/acetaminophen PRN
  • Significant decline in renal function: creatinine increased from 1.5 to 2.1 over six months

Medication Requiring Dose Adjustment

Apixaban

• Apixaban requires dose adjustment with declining renal function 1, 2
• According to ACC/AHA/HRS guidelines, apixaban dosing is based on renal function, age, and body weight 1
• With creatinine of 2.1 mg/dL (indicating worsening renal impairment), the patient likely meets criteria for dose reduction to 2.5 mg twice daily, especially if he has any of the following:
  • Age ≥80 years (patient is 74)
  • Body weight ≤60 kg
  • Serum creatinine ≥1.5 mg/dL (patient's is 2.1 mg/dL) 1, 2

Other Medications Assessment

1. Losartan

   • No dose adjustment is necessary for losartan in patients with renal impairment unless the patient is also volume depleted 3
   • The FDA label states: "No dose adjustment is necessary in patients with renal impairment unless a patient with renal impairment is also volume depleted" 3

2. Metoprolol

   • No specific dose adjustment required for metoprolol in this level of renal impairment

3. Opioids (Morphine and Hydrocodone/Acetaminophen)

   • While opioids should be used cautiously in renal impairment, no specific dose adjustment is mandated at this level of renal dysfunction

Monitoring Recommendations

1. For Apixaban:

   • Renal function should be evaluated before initiation and at least annually
   • More frequent monitoring (every 3 months) is recommended for patients with eGFR <30 mL/min/1.73 m² 2
   • Monitor for signs of bleeding

2. For All Medications:

   • Regular monitoring of renal function is essential
   • Assess for drug interactions that may increase bleeding risk
   • Monitor blood pressure control

Potential Pitfalls

• Failure to adjust apixaban dosing based on declining renal function increases bleeding risk 1, 2
• Inadequate monitoring of renal function in patients on multiple medications affecting the cardiovascular system
• Overlooking the significance of a rapid decline in renal function (creatinine from 1.5 to 2.1 in six months), which may require nephrology referral
• Ignoring potential drug interactions between the patient's multiple medications

Follow-up Recommendations

• Reassess renal function within 1-3 months
• Consider nephrology consultation given the significant decline in renal function
• Evaluate for causes of worsening renal function, which may include the current medication regimen

Remember that timely dose adjustment of apixaban is critical to maintain the balance between preventing thromboembolism and avoiding bleeding complications in this patient with worsening renal function.