Is it appropriate to discontinue triamterene hydrochlorothiazide (Dyazide) and start amlodipine in an elderly female patient with dizziness and fainting, who is already on losartan and triamterene hydrochlorothiazide?

Management of Dizziness and Fainting in an Elderly Female on Losartan and Triamterene-Hydrochlorothiazide

Do not discontinue the triamterene-hydrochlorothiazide (Dyazide) and switch to amlodipine without first confirming orthostatic hypotension and assessing whether the current regimen is causing symptomatic hypotension. The dizziness and fainting are likely medication-related, but the priority is to identify the culprit drug(s) and adjust dosing rather than making an arbitrary switch that could introduce new adverse effects.

Immediate Diagnostic Assessment Required

Measure lying and standing blood pressures to confirm orthostatic hypotension, defined as a drop of ≥20 mmHg systolic or ≥10 mmHg diastolic within 3 minutes of standing 1. This is critical because:

• Orthostatic hypotension occurs in approximately 7% of men over 70 years and carries a 64% increase in age-adjusted mortality, plus increased risk of falls and fractures 1
• The combination of losartan (an ARB) and triamterene-hydrochlorothiazide creates additive hypotensive effects that commonly cause dizziness 2, 3
• Dizziness was reported as the most common drug-related adverse effect with losartan (6.0% incidence) 4

Verify the patient's current blood pressure control to determine if she is being overtreated. The target systolic BP should be <150 mmHg for most patients ≥60 years to reduce mortality, stroke, and cardiac events 1. Aggressive BP targets (<140 mmHg) show only small additional benefits with inconsistent results 1.

Why Switching to Amlodipine May Be Problematic

Amlodipine would likely worsen the patient's symptoms rather than improve them for several reasons:

• Dizziness occurs in 1.1-3.4% of patients on amlodipine in a dose-related manner 5
• Peripheral edema is significantly more common in elderly women taking amlodipine (14.6% in women vs 5.6% in men) 5
• In direct comparison trials, amlodipine caused significantly more drug-related adverse events (43.8%) and discontinuations (12.9%) compared to losartan (25.5% and 4.4%, respectively) 4
• The combination of losartan with amlodipine would create triple antihypertensive therapy (losartan + amlodipine + existing HCTZ), substantially increasing hypotension risk 6

Recommended Management Algorithm

Step 1: Adjust Current Regimen Based on Orthostatic Findings

If orthostatic hypotension is confirmed:

• Reduce or discontinue the triamterene-hydrochlorothiazide first, as diuretics aggravate orthostatic hypotension through volume depletion 1
• Continue losartan 100mg, as ARBs have lower rates of dizziness compared to other antihypertensives and provide proven cardiovascular benefits 4
• Most hypotension, dizziness, and syncope in heart failure trials was not related to the initiation of guideline-directed medical therapy, so providers should be thoughtful about whether symptoms should prompt discontinuation, especially if patients have borderline blood pressure 7

If blood pressure is below target (<150 mmHg systolic):

• Reduce losartan dose to 50mg daily before considering complete discontinuation 2
• Monitor renal function (creatinine, potassium) within 1-2 weeks after any ARB dose adjustment 8

Step 2: If Blood Pressure Remains Uncontrolled After Adjustment

Only if blood pressure remains elevated (>150 mmHg systolic) after reducing diuretic:

• Consider adding amlodipine 2.5mg daily (the lowest dose for elderly patients with decreased clearance) 5
• Warn the patient about peripheral edema risk (14.6% in elderly women) 5
• If edema develops, increase the losartan dose rather than discontinuing amlodipine, as ARBs cause venous dilation that counterbalances amlodipine's arteriolar effects 8

Step 3: Alternative Options If Symptoms Persist

If dizziness continues despite medication adjustment:

• Evaluate for non-medication causes: vestibular disorders, cardiovascular disease, CNS pathology 7, 9
• Consider switching from triamterene-hydrochlorothiazide to chlorthalidone 12.5mg once daily, which has a more predictable dose-response and proven cardiovascular benefits 8
• Monitor electrolytes closely, as elderly women are at higher risk for hyponatremia and hypokalemia with thiazide diuretics 7

Critical Pitfalls to Avoid

• Do not rely solely on seated blood pressure measurements, as this misses orthostatic hypotension 1
• Do not assume dizziness is unrelated to medications without checking orthostatic vitals 1
• Do not continue aggressive BP lowering in elderly patients experiencing dizziness without reassessing targets 1
• Do not abruptly discontinue losartan without ensuring alternative blood pressure control, as uncontrolled hypertension poses significant cardiovascular risk 8
• Recognize that polypharmacy in patients ≥75 years increases the risk of potentially inappropriate medications causing adverse drug reactions, including falls and dizziness 1

Monitoring After Any Intervention

• Recheck orthostatic blood pressures within 1-2 weeks 1
• Monitor serum potassium and creatinine if adjusting ARB dose 8
• Assess for symptom resolution and blood pressure control at each visit 1