Can the dose of losartan (an angiotensin II receptor antagonist) be increased in a patient with hypertension, currently taking losartan 50mg daily, who has developed increased blood pressure after starting Strattera (atomoxetine), an attention deficit hyperactivity disorder (ADHD) medication?

Managing Blood Pressure Elevation After Starting Strattera in a Patient on Losartan

Yes, increase the losartan dose from 50mg to 100mg daily, as this represents standard dose optimization within the current medication regimen and is the appropriate first step before adding additional antihypertensive agents. 1, 2

Rationale for Dose Escalation

• The FDA-approved dosing for losartan in hypertension allows for titration up to 100mg once daily as needed to control blood pressure, with the usual starting dose being 50mg daily 2
• The HEAAL trial demonstrated that losartan 150mg daily was superior to 50mg daily, with a 10% relative risk reduction in death or heart failure hospitalization, underscoring that higher doses of renin-angiotensin system blockers provide greater benefit 1
• Losartan exhibits dose-proportional pharmacokinetics, with maximum blood pressure reductions occurring after doses of approximately 50mg, though some patients require 100mg for adequate control 3, 4

Addressing the Strattera-Induced Blood Pressure Elevation

• The 2017 ACC/AHA guidelines explicitly identify amphetamines (including atomoxetine/Strattera) as medications that can cause elevated blood pressure, recommending either discontinuation/dose reduction or intensification of antihypertensive therapy 1
• Since Strattera is providing therapeutic benefit for ADHD, the appropriate strategy is to optimize the current antihypertensive regimen rather than discontinue the ADHD medication 1
• The guidelines suggest considering behavioral therapies for ADHD as an adjunct, but do not mandate discontinuation of effective pharmacotherapy 1

Implementation Strategy

• Increase losartan from 50mg to 100mg once daily, which can be administered without regard to food 2, 3
• Reassess blood pressure within 2-4 weeks after dose adjustment, as maximum antihypertensive effects are typically apparent within 2 weeks, with maximal reduction generally attained after 4 weeks 2
• Target blood pressure should be <140/90 mmHg minimum, ideally <130/80 mmHg for higher-risk patients 1, 5

If Blood Pressure Remains Uncontrolled After Losartan 100mg

• Add a calcium channel blocker (amlodipine 5-10mg daily) or a thiazide-like diuretic (chlorthalidone 12.5-25mg daily or hydrochlorothiazide 12.5-25mg daily) as the second agent to achieve guideline-recommended dual therapy 1, 5
• The combination of losartan with hydrochlorothiazide has been extensively studied and demonstrates excellent efficacy, with the addition of 12.5mg HCTZ to 50mg losartan producing significant additional blood pressure reductions 2, 6, 7
• For patients requiring triple therapy, the evidence-based combination is ARB + calcium channel blocker + thiazide diuretic, targeting complementary mechanisms of renin-angiotensin system blockade, vasodilation, and volume reduction 1, 5

Critical Monitoring Parameters

• Check serum potassium and creatinine 2-4 weeks after increasing losartan dose, as ARBs can cause hyperkalemia and changes in renal function 1, 5
• Monitor for symptomatic hypotension, though first-dose hypotension is uncommon with losartan due to its slower onset of action 6, 7
• Assess medication adherence before further treatment intensification, as non-adherence is the most common cause of apparent treatment resistance 1, 5

Important Caveats to Avoid

• Do not combine losartan with an ACE inhibitor, as dual renin-angiotensin system blockade increases adverse events (hyperkalemia, acute kidney injury) without additional cardiovascular benefit 1, 5
• Do not delay treatment intensification—if blood pressure remains elevated after optimizing losartan to 100mg, promptly add a second agent rather than waiting prolonged periods 1, 5
• Do not discontinue Strattera solely due to blood pressure elevation if it is providing therapeutic benefit for ADHD, as optimizing antihypertensive therapy is the preferred approach 1
• Verify that the patient is not taking other medications that elevate blood pressure, including NSAIDs, decongestants, oral contraceptives, or herbal supplements like ephedra 1