What dose of olmesartan (angiotensin II receptor antagonist) to start with when switching a patient from lisinopril (angiotensin-converting enzyme inhibitor) 40mg to olmesartan due to refractory hypertension while on lisinopril and amlodipine (calcium channel blocker)?

Olmesartan Dosing When Switching from Lisinopril 40mg

Start olmesartan at 20 mg once daily when switching from lisinopril 40 mg in this patient with refractory hypertension on dual therapy. 1

Recommended Starting Dose

• Olmesartan 20 mg once daily is the standard starting dose for adult hypertension, regardless of prior ACE inhibitor therapy 1
• The FDA-approved dosing for olmesartan begins at 20 mg once daily for monotherapy, with titration to 40 mg after 2 weeks if additional blood pressure reduction is needed 1
• Doses above 40 mg do not provide greater antihypertensive effect 1

Rationale for Conservative Starting Dose

• Despite the patient being on lisinopril 40 mg (a relatively high dose), starting olmesartan at the standard 20 mg dose is appropriate because ARBs and ACE inhibitors are not dose-equivalent on a 1:1 basis 1
• The patient is already on amlodipine, which means they are volume-depleted risk and should be monitored closely when initiating the ARB 1
• Starting at 20 mg allows assessment of tolerability and blood pressure response before escalation 1

Titration Strategy

• Reassess blood pressure after 2 weeks on olmesartan 20 mg 1
• If blood pressure remains uncontrolled, increase to olmesartan 40 mg once daily 1
• The combination of olmesartan 40 mg with amlodipine 5-10 mg has demonstrated significant blood pressure reductions in patients with moderate-to-severe hypertension, with goal achievement rates of 44.5-53.2% 2

Important Clinical Considerations

• Twice-daily dosing of olmesartan offers no advantage over once-daily administration of the same total dose 1
• Monitor for hypotension, particularly in the first few weeks after switching, as the patient is on concurrent amlodipine 1
• The olmesartan/amlodipine combination is well-tolerated, with the most common adverse event being peripheral edema (related to amlodipine) 2, 3
• If blood pressure remains refractory on olmesartan 40 mg plus amlodipine, consider adding hydrochlorothiazide as triple therapy, which has shown BP goal achievement rates of 44.5-79.8% 4