What is the equivalent dosage when switching from olmesartan (Angiotensin II Receptor Blocker) to telmisartan (Angiotensin II Receptor Blocker), or vice versa?

Olmesartan to Telmisartan Dose Equivalence

When switching between olmesartan and telmisartan, use a 1:2 ratio: olmesartan 20 mg is equivalent to telmisartan 40 mg, and olmesartan 40 mg is equivalent to telmisartan 80 mg. 1, 2

Standard Dose Conversion

Based on the ACC/AHA guidelines and practical conversion data:

• Olmesartan 20 mg daily → Telmisartan 40 mg daily 1, 2
• Olmesartan 40 mg daily → Telmisartan 80 mg daily 1, 2

The usual dose ranges are olmesartan 20-40 mg once daily and telmisartan 20-80 mg once daily, with both agents dosed once per day. 1

Clinical Evidence Supporting This Conversion

Direct comparative studies demonstrate that olmesartan 20 mg produces similar blood pressure reductions to telmisartan 40 mg, and olmesartan 40 mg matches telmisartan 80 mg in efficacy. 3, 4, 5

• In the COTO study, switching from telmisartan 40 mg to olmesartan 20 mg resulted in significant blood pressure reductions, and switching back to telmisartan caused blood pressure to rise again, confirming the 1:2 dose equivalence. 3
• A prospective randomized trial comparing olmesartan 20 mg to telmisartan 80 mg found both agents produced comparable ambulatory blood pressure reductions when combined with hydrochlorothiazide. 4
• A crossover study in diabetic hypertensive patients found olmesartan 40 mg and telmisartan 80 mg produced equivalent blood pressure reduction rates. 5

Practical Switching Algorithm

Start the new ARB at the equivalent dose without a washout period, then monitor blood pressure within 1-2 weeks. 2

1. Calculate the equivalent dose using the 1:2 ratio
2. Switch directly without tapering or washout
3. Monitor blood pressure, renal function, and potassium within 1-2 weeks 2
4. Titrate based on blood pressure response if needed 2

Important Clinical Caveats

Do not switch ARBs in heart failure patients with reduced ejection fraction unless there is a compelling reason, as specific ARBs have proven mortality benefits in this population. 2

• Valsartan has proven mortality benefit in heart failure with a target dose of 160 mg twice daily, and switching to other ARBs is not recommended unless necessary. 2
• Monitor for hyperkalemia, especially in patients with chronic kidney disease or those on potassium supplements or potassium-sparing drugs. 1
• Check for acute renal failure risk in patients with severe bilateral renal artery stenosis. 1
• Avoid in pregnancy. 1
• Do not combine with ACE inhibitors or direct renin inhibitors due to increased risk of hyperkalemia and renal dysfunction. 1

Metabolic Considerations

Olmesartan may provide additional metabolic benefits beyond blood pressure control in diabetic patients. 5

• In diabetic hypertensive patients, olmesartan 40 mg significantly reduced HbA1c, fasting plasma glucose, and HOMA-IR compared to telmisartan 80 mg, despite equivalent blood pressure reductions. 5
• Olmesartan increased HDL-cholesterol and HMW-adiponectin while decreasing hs-CRP, suggesting anti-inflammatory effects. 5