What is the difference between losartan and telmisartan for an older adult patient with hypertension, a history of dizziness, and currently on lisinopril and hydrochlorothiazide (HCTZ)?

Losartan vs. Telmisartan: Key Differences for Older Adults with Hypertension and Dizziness

For an older adult with hypertension, history of dizziness, and currently on lisinopril/HCTZ, telmisartan 80 mg is the superior choice over losartan because losartan requires 100-150 mg daily for optimal cardiovascular protection—not the commonly prescribed 50 mg dose—while telmisartan 80 mg provides equivalent or superior 24-hour blood pressure control with once-daily dosing. 1

Critical Dosing Differences

Losartan is frequently underdosed in clinical practice:

• Losartan requires 100-150 mg daily for optimal cardiovascular protection, as demonstrated in the LIFE trial which showed a 25% reduction in cerebrovascular events at these doses 1
• The commonly prescribed 50 mg dose is subterapéutico (subtherapeutic) and leaves patients inadequately protected 1
• The American Heart Association recommends losartan 100-150 mg daily for cardiovascular protection 1

Telmisartan dosing is more straightforward:

• Telmisartan 80 mg once daily provides complete 24-hour coverage with bioavailability of 58% at this dose 2
• Peak concentrations occur 0.5-1 hour after dosing with a terminal half-life of approximately 24 hours 2
• Trough plasma concentrations with once-daily dosing are 10-25% of peak concentrations, ensuring sustained effect 2

Pharmacokinetic Advantages of Telmisartan

Telmisartan has superior pharmacokinetic properties for older adults:

• Terminal half-life of 24 hours ensures consistent blood pressure control throughout the day and night 2
• Accumulation index of 1.5-2.0 with once-daily dosing provides stable steady-state levels 2

• 99.5% protein binding with volume of distribution of 500 liters indicates extensive tissue binding 2

• No dosage adjustment needed in elderly patients—pharmacokinetics do not differ between elderly and those younger than 65 years 2

Losartan has less favorable pharmacokinetics:

• Requires twice-daily dosing (100 mg BID) for many patients to achieve optimal cardiovascular protection 1
• Active metabolite E-3174 contributes to antihypertensive effect but adds complexity 3, 4

Specific Considerations for Dizziness History

Both ARBs can cause dizziness, but the risk profile differs:

• ARBs as a class are associated with dizziness, cough, and hyperkalemia 5
• Critical monitoring requirement: Measure blood pressure in both sitting and standing positions at every visit to assess orthostatic hypotension, which is particularly important in elderly patients with dizziness history 6, 7
• Low-quality evidence shows no difference in adverse events including dizziness in patients younger or older than 75 years 5

Switching from ACE inhibitor (lisinopril) to ARB:

• This switch is appropriate if the patient experienced ACE inhibitor-related cough, as ARBs have a similar incidence of cough to placebo in patients with ACE inhibitor-related cough history 4
• Both losartan and telmisartan are suitable alternatives to ACE inhibitors 5

Combination with Hydrochlorothiazide

Both agents combine effectively with HCTZ, but telmisartan shows advantages:

• Telmisartan/HCTZ provides significantly greater reductions in 24-hour mean blood pressure compared to losartan/HCTZ, primarily due to greater effect in the early morning hours 8
• Telmisartan/HCTZ is effective and well-tolerated in elderly, diabetics, and African-American patients 8
• The combination of telmisartan 80 mg/HCTZ 12.5-25 mg provides greater blood pressure reduction than monotherapy 8, 9

If switching from lisinopril/HCTZ:

• Replace with telmisartan 80 mg while continuing HCTZ 12.5-25 mg 8
• Monitor blood pressure in 2-4 weeks after the switch 1
• Measure sitting and standing blood pressure to assess orthostatic changes 6, 7

Blood Pressure Targets for Older Adults

Target blood pressure should guide medication selection:

• For adults ≥60 years, the American College of Physicians recommends systolic blood pressure <150 mmHg (strong recommendation, high-quality evidence) 5
• For high cardiovascular risk patients ≥60 years, consider targeting <140 mmHg systolic (weak recommendation, low-quality evidence) 5
• The American College of Cardiology recommends <130 mmHg systolic for noninstitutionalized, ambulatory, community-dwelling adults ≥65 years (Class I, Level A) 6
• Avoid reducing diastolic blood pressure below 60-70 mmHg to prevent compromising coronary perfusion 6

Practical Switching Algorithm

If currently controlled on lisinopril/HCTZ and switching due to cough or other ACE inhibitor side effect:

1. Switch to telmisartan 80 mg once daily while continuing current HCTZ dose 1, 8
2. Measure blood pressure (sitting and standing) in 2-4 weeks 6, 1
3. If blood pressure remains >130/80 mmHg, increase HCTZ to 25 mg or add another agent 1
4. Monitor serum potassium and renal function periodically 7

If considering losartan instead:

1. Must prescribe losartan 100 mg once daily minimum—do not use 50 mg 1
2. If blood pressure not controlled, titrate to 100 mg twice daily 1
3. Never substitute telmisartan 80 mg with losartan 50 mg—this is subtherapeutic 1

Common Pitfalls to Avoid

Critical errors when using losartan:

• Do not prescribe losartan 50 mg as equivalent to telmisartan 80 mg—this leaves the patient undertreated 1
• Do not combine ARBs with ACE inhibitors or direct renin inhibitors—this increases adverse events without additional benefit 1
• Do not accept suboptimal dosing based on age alone—community-dwelling elderly patients benefit from the same intensive targets as younger patients 6

Monitoring requirements for both agents:

• Always measure blood pressure in both sitting and standing positions in elderly patients 5, 6, 7
• Monitor renal function and serum potassium periodically, as both ARBs can cause hyperkalemia 7
• Do not intensify treatment based on a single blood pressure reading—confirm with multiple measurements over time 7
• Ensure medication adherence before considering intensification, as non-adherence is the most common cause of apparent uncontrolled hypertension 7

Specific Evidence for Older Adults

Losartan evidence in elderly:

• The LIFE trial showed losartan was more effective than atenolol in reducing cardiovascular events, particularly stroke, in 55-80 year old hypertensive patients with left ventricular hypertrophy 5
• Losartan is as effective as captopril, atenolol, enalapril, felodipine, and nifedipine in elderly patients with hypertension 3
• Better tolerated than atenolol in patients with isolated systolic hypertension (10.4% vs 23% adverse events) 3

Telmisartan evidence in elderly:

• Pharmacokinetics do not differ between elderly and younger patients—no dosage adjustment required 2
• Plasma concentrations are 2-3 times higher in females than males, but no dosage adjustment necessary 2
• Effective and well-tolerated in elderly, diabetics, and African-American patients when combined with HCTZ 8

Drug Interaction Considerations

Telmisartan has minimal drug interactions:

• Not metabolized by cytochrome P450 system 2
• No clinically significant interactions with acetaminophen, amlodipine, glyburide, simvastatin, hydrochlorothiazide, warfarin, or ibuprofen 2
• Some inhibition of CYP2C19 but generally not clinically significant 2

Both agents require monitoring when combined with:

• Potassium supplements or potassium-sparing diuretics (hyperkalemia risk) 5
• NSAIDs (reduced antihypertensive effect and potential renal dysfunction) 5