Hypertension: Initial Combination Therapy and Drug Selection

Definition and Therapeutic Rationale

Hypertension is a major risk factor for atherosclerotic cardiovascular disease and contributes to microvascular and macrovascular complications. It is frequently clinically silent, which promotes both patient and clinician inertia and contributes to inadequate long-term control.

The treatment objective is individualized blood-pressure reduction sufficient to reduce cardiovascular risk while preserving tolerability and daily function. Decisions should incorporate the confirmed blood-pressure level, absolute cardiovascular risk, comorbidities, frailty, anticipated treatment benefit, and patient preferences.

The source material describes hypertension using differing thresholds across international guidance. One framework defines confirmed hypertension as blood pressure consistently above 130/80 mmHg on more than two measurements obtained at separate times, whereas European recommendations for initial combination therapy refer principally to confirmed blood pressure ≥140/90 mmHg. Blood-pressure targets should therefore be individualized within the applicable guideline framework.

Combination therapy is based on the complementary mechanisms of drugs from different classes. By acting on more than one pathophysiological pathway, combinations generally lower blood pressure more effectively than simply increasing the dose of a single drug. They may also permit lower doses of each component, potentially limiting adverse effects and facilitating adherence. Treatment response, however, is heterogeneous, and some patients may benefit from a more individualized selection strategy.

When to Initiate Pharmacological Treatment

Lifestyle intervention is an essential component of care. In adults with elevated blood pressure, nonpharmacological management should be actively implemented. Adults with blood pressure ≥140/90 mmHg should receive both lifestyle and antihypertensive drug therapy. For grade 1 hypertension, pharmacological treatment has demonstrated cardiovascular benefit, although in younger individuals with low short-term risk, lifetime benefit should be considered and discussed.

Where blood pressure is more than 20/10 mmHg above the treatment goal, lifestyle and pharmacological treatment should be initiated concurrently. In patients with a confirmed indication for treatment but blood pressure in the range of 120–139/70–89 mmHg, concomitant indications and overall cardiovascular risk influence whether medication is added to lifestyle intervention.

Initial monotherapy may be appropriate when blood pressure is close to target and is likely to reach goal with one agent. It may also be preferable in patients aged ≥85 years, those with symptomatic orthostatic hypotension, moderate-to-severe frailty, or very old or frail patients who may not tolerate rapid blood-pressure reduction.

Initial Combination Therapy

General Strategy

For most adults with confirmed hypertension, initial treatment with two agents is recommended. European guidance gives this strategy a Class I recommendation with Level B evidence in patients with blood pressure ≥140/90 mmHg, with important exceptions for advanced age, frailty, orthostatic symptoms, and blood pressure close to target.

Low-dose combination therapy generally produces faster and more consistent blood-pressure reduction than monotherapy. It may also reduce treatment inertia, in which patients remain on an inadequate single-drug regimen for prolonged periods. The evidence supports improved blood-pressure control and adherence, although prospective outcome trials have not directly established that upfront combination therapy is superior to upfront monotherapy for every patient with isolated hypertension.

Single-Pill Combinations

Fixed-dose, single-pill combinations are preferred whenever combination treatment is used. The number of prescribed tablets is directly related to adherence, and simplifying the regimen may improve persistence and control. Medication should be taken at the most convenient time of day for the individual, thereby creating a consistent habitual pattern.

Cost, monitoring requirements, drug selectivity, and tolerability should also influence the choice of preparation. Lower-cost alternatives may be important when medication expense threatens adherence.

Preferred Two-Drug Combinations

The principal first-line classes are:

• ACE inhibitors

• Angiotensin receptor blockers

• Dihydropyridine calcium channel blockers

• Thiazide or thiazide-like diuretics

For most patients, the preferred initial combination is:

• An ACE inhibitor or ARB plus a dihydropyridine CCB, or

• An ACE inhibitor or ARB plus a thiazide or thiazide-like diuretic

The source material also identifies beta-blockers as a major class with cardiovascular benefit, but recommends their use primarily when a specific indication is present rather than as routine initial therapy for uncomplicated hypertension.

Three-Drug Therapy

If blood pressure remains uncontrolled with two drugs, treatment should generally be intensified to a three-drug regimen consisting of:

• A RAS blocker—either an ACE inhibitor or an ARB;

• A dihydropyridine CCB; and

• A thiazide or thiazide-like diuretic.

A single-pill formulation is preferred when available.

Resistant Hypertension

Persistent uncontrolled blood pressure despite maximally tolerated triple therapy should prompt confirmation of adherence and referral for specialist assessment and appropriate work-up. Spironolactone should be considered as the next pharmacological step.

If spironolactone is ineffective or not tolerated, options include:

• Eplerenone;

• A beta-blocker, if no compelling indication already exists;

• A centrally acting antihypertensive;

• An alpha-blocker;

• Hydralazine; or

• A potassium-sparing diuretic.

These latter agents should generally be reserved for later-line treatment. Minoxidil is considered only when other pharmacological options have failed because of its multiple adverse effects.

Drug Selection by Class

Renin–Angiotensin–Aldosterone System Blockers

ACE inhibitors and ARBs are major first-line agents and are especially useful when treatment requires combination therapy. They are associated with benefit in patients with myocardial infarction, reduced systolic function, heart failure, diabetic renal disease, and hypertensive nephrosclerosis.

ACE inhibitor– or ARB-based therapy is also emphasized in patients receiving cancer treatment who develop hypertension, particularly because uncontrolled hypertension is a risk factor for heart failure during treatment with anthracyclines, ibrutinib, and vascular endothelial growth factor inhibitors.

An ACE inhibitor and an ARB must not be combined. Dual RAS blockade does not improve outcomes and increases harm; this is a Class III recommendation with Level A evidence.

In older adults, RAS blockade may be less effective as initial blood-pressure therapy because renin activity tends to be lower. Nevertheless, these drugs remain useful adjuncts and may provide important cardiovascular and renal protection. Older patients, particularly those more than 70 years of age, may be vulnerable to reduced kidney function during RAS blockade when fluid intake is low; adequate hydration and renal monitoring are therefore important practical considerations.

Calcium Channel Blockers

Dihydropyridine CCBs are recommended first-line agents and are particularly suitable for older patients with arterial dysfunction and reduced arterial compliance. Their principal adverse effects are related to vasodilation and include:

• Ankle oedema;

• Headache; and

• Postural hypotension.

The ankle oedema associated with CCBs is attributed primarily to profound vasodilation and impaired venous return rather than sodium retention.

Immediate-release preparations such as nifedipine should be avoided in patients with left-ventricular dysfunction. Non-dihydropyridine CCBs, including verapamil and diltiazem, may precipitate heart block in older patients with pre-existing conduction disease and should be used cautiously in that setting.

In selected patients with cancer who cannot tolerate multiple other antihypertensive agents, diltiazem or verapamil may be considered, with close attention to drug–drug interactions.

Thiazide and Thiazide-Like Diuretics

Thiazide-type diuretics include hydrochlorothiazide, chlorthalidone, indapamide, and bendrofluazide. They are recommended as first-line treatment and are particularly effective in older patients.

Their initial effects include reduction of intravascular volume, peripheral vascular resistance, and blood pressure. They are generally well tolerated and inexpensive. Important electrolyte complications include:

• Hypokalaemia;

• Hypomagnesaemia; and

• Hyponatraemia.

They are therefore unsuitable for patients with baseline electrolyte disturbances or a history of hyponatraemia unless the clinical circumstances permit careful correction and monitoring. Serum potassium should be followed, with supplementation when necessary. Combining a diuretic with a RAS blocker or, where appropriate, a mineralocorticoid receptor antagonist may help prevent potassium depletion, although the source material does not provide a specific monitoring schedule.

Beta-Blockers

Beta-blockers should generally be used when a compelling indication exists. These include:

• Angina;

• Previous myocardial infarction;

• Arrhythmia;

• Heart failure with reduced ejection fraction;

• Coronary artery disease; and

• Heart-rate control.

Their role as monotherapy in uncomplicated hypertension, particularly in older patients, is poorly documented. When beta-blockade is selected for resistant hypertension without another compelling indication, a vasodilating agent such as labetalol, carvedilol, or nebivolol is preferred. Beta-blockade may be less potent than spironolactone in resistant hypertension.

Nebivolol is described as a selective beta1-blocker with nitric oxide-related properties and may avoid some adverse metabolic and sexual effects associated with earlier beta-blockers in older adults.

In patients with cancer and evidence of increased sympathetic tone, stress, or pain, carvedilol or nebivolol may be considered.

Mineralocorticoid Receptor Antagonists

Spironolactone is the preferred fourth-line agent when blood pressure remains uncontrolled on a RAS blocker, CCB, and diuretic. It is particularly useful in resistant hypertension, heart failure, and primary aldosteronism.

Eplerenone is an alternative when spironolactone is not tolerated. It is more selective and causes less gynecomastia and sexual dysfunction, but generally lowers blood pressure less effectively and may require twice-daily administration because of its shorter duration of action. Effective blood-pressure treatment may require eplerenone doses of 50–200 mg; 25 mg did not lower blood pressure in the cited meta-analysis.

Potassium-sparing diuretics, including mineralocorticoid receptor antagonists, are most appropriately used in patients with estimated glomerular filtration rate >45 mL/min, because the risk of hyperkalaemia increases with lower renal function.

Potassium-Sparing Diuretics

Amiloride and triamterene are most useful in combination with another diuretic. They should be considered later in the treatment pathway, particularly after the preferred triple regimen and mineralocorticoid receptor antagonist strategies have been assessed.

Alpha-Blockers and Centrally Acting Agents

Alpha-blockers and centrally acting drugs such as clonidine and guanfacine are not recommended as first- or second-line agents in older adults. They are reserved for later combination regimens when blood pressure remains inadequately controlled despite use of preferred agents.

Direct Vasodilators

Hydralazine is a later-line option in resistant hypertension. Minoxidil should be reserved for cases in which other pharmacological approaches have proved ineffective because of its adverse-effect burden.

Management in Older Adults

Thiazide-type diuretics and CCBs are the principal initial agents in older patients. ACE inhibitors and ARBs remain effective adjuncts but may be less successful as initial monotherapy because of lower renin status.

Treatment intensity must be individualized. Older adults should be treated to a blood-pressure level they can tolerate while maintaining function and avoiding complications such as falls. Evidence regarding very low systolic targets is not uniform, particularly in patients with marked arterial stiffness and pulse pressure >90 mmHg.

Immediate-release nifedipine, verapamil, and diltiazem should be avoided in older patients with left-ventricular dysfunction, while non-dihydropyridine CCBs require caution in the presence of conduction disease. Electrolytes and renal function require attention when diuretics or RAS blockers are prescribed.

Hypertension Associated With Cancer Therapy

Cancer treatment can cause hypertension through agents including vascular endothelial growth factor inhibitors, newer BCR-ABL tyrosine kinase inhibitors, brigatinib, ibrutinib, fluoropyrimidines, cisplatin, abiraterone, bicalutamide, and enzalutamide. Non-cancer drugs and clinical factors—including corticosteroids, non-steroidal anti-inflammatory drugs, pain, stress, excessive alcohol consumption, renal impairment, untreated sleep apnoea, obesity, and reduced exercise—may also contribute.

Before interrupting anticancer therapy, these potentially reversible causes should be assessed and corrected where possible.

ACE inhibitors or ARBs are recommended as first-line therapy in this setting. When systolic blood pressure is ≥160 mmHg or diastolic blood pressure is ≥100 mmHg, combination treatment with an ACE inhibitor or ARB plus a dihydropyridine CCB is recommended for more rapid control.

Severe hypertension, defined in the source material as systolic blood pressure ≥180 mmHg or diastolic blood pressure ≥110 mmHg, requires multidisciplinary assessment of competing cancer and cardiovascular risks. Anticancer treatment associated with hypertension should be deferred or temporarily withheld until blood pressure is <160/<100 mmHg. Re-initiation may then be considered, with possible dose reduction.

For resistant cancer-treatment-related hypertension, possible treatments include:

• Spironolactone;

• Oral or transdermal nitrates;

• Hydralazine;

• Carvedilol or nebivolol when sympathetic activation, stress, or pain is prominent; and

• Diuretics, preferably spironolactone, where fluid retention is present.

Blood pressure, electrolytes, and renal function should be monitored when diuretics are used. Treatment decisions and targets must take account of the cancer context and prognosis.

Practical Treatment Algorithm

Guideline Recommendations

The principal recommendations are:

• ACE inhibitors, ARBs, dihydropyridine CCBs, and thiazide or thiazide-like diuretics are recommended first-line agents for blood-pressure and cardiovascular-event reduction.

• Beta-blockers should be combined with other major antihypertensive classes when a compelling indication exists, such as angina, previous myocardial infarction, heart failure with reduced ejection fraction, or heart-rate control.

• Combination therapy is recommended as initial treatment for most patients with confirmed hypertension, particularly when blood pressure is ≥140/90 mmHg.

• Fixed-dose single-pill treatment is recommended when combination therapy is used.

• If a two-drug regimen is inadequate, escalation to a RAS blocker, dihydropyridine CCB, and thiazide or thiazide-like diuretic is recommended.

• Spironolactone should be considered when blood pressure remains uncontrolled on triple therapy.

• Eplerenone or alternative later-line agents should be considered when spironolactone is ineffective or not tolerated.

• ACE inhibitor–ARB combination therapy is not recommended.

• Treatment timing should be selected to facilitate habitual medication use and adherence.

Adherence and Long-Term Follow-Up

Hypertension control is limited chiefly by poor adherence, despite the availability of effective, well-tolerated, and inexpensive medications. The low symptom burden of hypertension contributes to treatment inertia. Long-term follow-up should therefore include assessment of blood-pressure control, tolerability, adherence, regimen complexity, affordability, and the need for stepwise intensification.

A single-pill strategy, convenient dosing time, and use of complementary agents at tolerable doses are central practical approaches. In older patients, follow-up should additionally consider orthostatic symptoms, falls, electrolyte abnormalities, renal function, hydration, and preservation of daily function. In patients with diabetes, home blood-pressure monitoring is recommended irrespective of the antihypertensive regimen.

The source material does not provide a specific follow-up interval, laboratory schedule, or drug-dose titration timetable beyond the stated eplerenone dosing considerations.