What is the best add-on medication for an 88-year-old patient with hypertension (high blood pressure) and hyponatremia (low sodium levels) who is already on maximum doses of telmisartan (Angiotensin II receptor antagonist) and amlodipine (calcium channel blocker)?

Management of Resistant Hypertension in an 88-Year-Old with Hyponatremia

For an 88-year-old patient with hypertension who is already on maximum doses of telmisartan and amlodipine and has hyponatremia, a mineralocorticoid receptor antagonist like eplerenone should be added as the next agent rather than spironolactone to avoid worsening hyponatremia. 1

Assessment of Current Situation

This patient has resistant hypertension, defined as blood pressure that remains above goal despite concurrent use of 3 antihypertensive agents of different classes, including a diuretic, at optimal doses 1. The current regimen includes:

• Telmisartan (an ARB) at maximum dose
• Amlodipine (a calcium channel blocker) at maximum dose
• No diuretic yet

The complicating factor is hyponatremia, which requires careful medication selection.

Recommended Treatment Algorithm

Step 1: Add a Thiazide-like Diuretic

• Add chlorthalidone 12.5-25 mg daily or indapamide 1.25-2.5 mg daily 1
• These thiazide-like diuretics are preferred over hydrochlorothiazide due to their longer duration of action and superior evidence for cardiovascular outcomes 1
• Caution: Monitor sodium levels closely as thiazide diuretics can worsen hyponatremia

Step 2: If BP Control Not Achieved After 2-4 Weeks

• Add eplerenone 50-100 mg daily (preferred over spironolactone) 1
• Eplerenone is less likely to cause sexual side effects than spironolactone, which is particularly important in elderly patients 1
• Important: Initiate at a lower dose (25 mg daily) in this elderly patient and titrate cautiously

Step 3: If BP Control Still Not Achieved

• Check heart rate:
  • If heart rate ≥70 bpm: Add metoprolol succinate 25-50 mg daily or bisoprolol 2.5-5 mg daily 1
  • If heart rate <70 bpm or beta-blockers contraindicated: Consider once-daily diltiazem 1

Special Considerations for This Patient

Hyponatremia Management

• Avoid high-dose thiazide diuretics which can worsen hyponatremia 2
• Monitor sodium levels closely after initiating any new antihypertensive medication
• Consider tolvaptan if hyponatremia worsens significantly, but only in a hospital setting with close monitoring due to risk of osmotic demyelination syndrome 3

Age-Related Considerations

• Start with lower doses and titrate more slowly due to age (88 years)
• Target blood pressure should be individualized based on frailty status, with a less aggressive goal (e.g., <150/90 mmHg) if frail 1
• Monitor for orthostatic hypotension with each medication adjustment

Medication Adherence

• Consider once-daily dosing when possible
• Evaluate for single-pill combinations to improve adherence (e.g., telmisartan/amlodipine) 4, 5

Monitoring Recommendations

• Check electrolytes (particularly sodium and potassium) and renal function 1-2 weeks after initiating new therapy
• Schedule follow-up blood pressure check within 2-4 weeks of medication changes
• Assess for adverse effects, particularly:
  • Worsening hyponatremia
  • Hyperkalemia (especially if adding eplerenone)
  • Orthostatic hypotension
  • Dizziness or falls

Common Pitfalls to Avoid

1. Avoid spironolactone in this patient with hyponatremia as it may worsen the condition
2. Avoid combining ARBs with ACE inhibitors as this increases adverse effects without additional benefit 6
3. Avoid rapid titration of medications in elderly patients, which can lead to adverse effects
4. Don't overlook adherence issues - ensure the patient is actually taking the prescribed medications
5. Don't forget to rule out secondary causes of resistant hypertension, including sleep apnea, primary aldosteronism, renal artery stenosis, and medication interactions

By following this algorithm and carefully monitoring the patient's response, blood pressure control can be achieved while minimizing the risk of worsening hyponatremia or other adverse effects in this elderly patient.