What is the best course of action for a 55-year-old patient with uncontrolled hypertension (high blood pressure), currently on amlodipine (calcium channel blocker) 10 mg once daily, with a blood pressure reading of 180/98 mmHg?

Management of Uncontrolled Hypertension on Maximum-Dose Amlodipine

Add either an ACE inhibitor/ARB or a thiazide-like diuretic as the second antihypertensive agent to achieve guideline-recommended dual therapy for this patient with stage 2 hypertension (180/98 mmHg) on amlodipine 10 mg daily. 1

Immediate Assessment Required

Before adding medication, confirm this blood pressure elevation represents true hypertension rather than white-coat effect:

• Arrange home blood pressure monitoring or 24-hour ambulatory monitoring, with home BP ≥135/85 mmHg or 24-hour ambulatory BP ≥130/80 mmHg confirming sustained hypertension requiring treatment intensification 1
• Verify medication adherence first, as non-adherence is the most common cause of apparent treatment resistance 1, 2
• Rule out secondary causes if BP remains severely elevated: primary aldosteronism, renal artery stenosis, obstructive sleep apnea, and medication interference 1

Recommended Second Agent Selection

For most patients (non-Black): Add an ACE inhibitor or ARB as the preferred second agent 1

• This combination provides complementary mechanisms—vasodilation through calcium channel blockade and renin-angiotensin system inhibition 1
• The combination of amlodipine with an ACE inhibitor has demonstrated superior blood pressure control compared to either agent alone 1
• ACE inhibitors/ARBs are particularly beneficial for patients with chronic kidney disease, heart failure, or coronary artery disease 1
• Adding an ACE inhibitor or ARB may attenuate peripheral edema commonly seen with amlodipine 1

For Black patients specifically: The combination of amlodipine plus a thiazide diuretic may be more effective than amlodipine plus an ACE inhibitor/ARB 1

Alternative option (any patient): Add a thiazide-like diuretic (chlorthalidone 12.5-25 mg daily or hydrochlorothiazide 25 mg daily) 1, 2

• Particularly effective for volume-dependent hypertension, elderly patients, or Black patients 1
• Chlorthalidone is preferred over hydrochlorothiazide due to its longer duration of action and proven cardiovascular outcome benefits 2

Monitoring After Adding Second Agent

• Recheck blood pressure within 2-4 weeks after medication adjustment 1, 2
• Target blood pressure should be <140/90 mmHg minimum, ideally <130/80 mmHg 1, 2
• When adding an ACE inhibitor/ARB: Monitor serum potassium and creatinine 2-4 weeks after initiation to detect hyperkalemia or acute kidney injury 1
• When adding a thiazide diuretic: Monitor serum potassium and creatinine 2-4 weeks after initiation to detect hypokalemia 1, 2
• Goal is to achieve target blood pressure within 3 months of initiating or modifying therapy 1

If Blood Pressure Remains Uncontrolled on Dual Therapy

Add a third agent from the remaining class to achieve guideline-recommended triple therapy: ACE inhibitor/ARB + calcium channel blocker + thiazide diuretic 1, 2

• This represents the most effective three-drug combination for resistant hypertension 1, 2
• Do not add a third drug class before maximizing doses of the current two-drug regimen 1
• If blood pressure remains uncontrolled after optimizing triple therapy, add spironolactone 25-50 mg daily as the preferred fourth-line agent for resistant hypertension 1

Critical Pitfalls to Avoid

• Do not combine ACE inhibitors with ARBs due to increased risk of adverse effects (hyperkalemia, acute kidney injury) without additional benefit 1
• Do not add a beta-blocker as the second or third agent unless there are compelling indications such as angina, post-myocardial infarction, heart failure with reduced ejection fraction, or need for heart rate control 1
• Do not delay treatment intensification for stage 2 hypertension—this patient's BP of 180/98 mmHg is >30 mmHg above target and warrants immediate action to reduce cardiovascular risk 1, 2
• Do not assume treatment failure without first confirming adherence and ruling out secondary causes of hypertension 1

Special Considerations for This 55-Year-Old Patient

Given the patient's age (55 years), amlodipine titration from 5 mg to 10 mg has been shown to significantly decrease blood pressure in this age group with good tolerability 3

• The current dose of amlodipine 10 mg is the maximum approved dose for hypertension 4
• Further dose escalation of amlodipine is not an option—adding a second agent is required 4