Spironolactone compared with usual first blood pressure medicines in low-renin hypertension
Compares spironolactone with standard first-line blood pressure medicines in adults with low-renin hypertension.
Plain-language title generated from the registry record
Registry title: SPIRO-First: A Pragmatic Primary Care-Embedded Pilot Trial of Renin-Guided First-Line Antihypertensive Therapy
Key facts
- Where
- Laval, Ottawa, and Saint Isidore, CanadaSee the 4 sites
- Phase
- Phase 4
Where in Canada
- GMF Universitaire LavalLaval, CanadaNo longer taking part
- Ottawa Nurse Practitioner-Led ClinicOttawa, CanadaNo longer taking part
- The Ottawa HospitalOttawa, CanadaNo longer taking part
- St-Isidore MédicalSaint Isidore, CanadaNo longer taking part
Questions to ask the study team
- How often do I need to come in, and for how long each time?
- Are travel costs paid?
- Can I keep my own doctor?
- What happens if I want to stop?
Trial details
- Who runs it
- Ottawa Hospital Research Institute
- Trial code
- NCT07687160
- Record updated
- 14 October 2026
- Original description
The goal of this clinical trial is to determine whether a renin-guided antihypertensive treatment strategy is feasible to implement in community primary care clinics and to explore whether spironolactone improves blood pressure control in adults with low-renin hypertension.Read full original descriptionShow less
SPIRO-First: A Pragmatic Primary Care-Embedded Pilot Trial of Renin-Guided First-Line Antihypertensive Therapy
The goal of this clinical trial is to determine whether a renin-guided antihypertensive treatment strategy is feasible to implement in community primary care clinics and to explore whether spironolactone improves blood pressure control in adults with low-renin hypertension.
The main questions it aims to answer are:
Is it feasible to identify, recruit, randomize, and follow adults with low-renin hypertension in a pragmatic primary care-based clinical trial?
Does first-line treatment with spironolactone result in greater reductions in ambulatory blood pressure compared with standard first-line antihypertensive therapy among adults with low-renin hypertension?
Researchers will compare spironolactone 25 mg daily with standard first-line antihypertensive therapy (candesartan, hydrochlorothiazide, or amlodipine) to determine whether spironolactone provides better blood pressure control in adults with low-renin hypertension.
Participants will:
Undergo blood pressure assessments, blood tests, and ambulatory blood pressure monitoring (ABPM) to determine eligibility.
Be randomly assigned to receive either spironolactone or a standard first-line antihypertensive medication for 12 weeks.
Complete follow-up visits and laboratory testing to monitor blood pressure response, kidney function, electrolyte levels, medication adherence, and side effects.
Undergo repeat blood pressure measurements and ABPM at the end of the study.
Inclusion: Age ≥18 years; Under the care of a primary care clinician in Ontario; Standardized office systolic blood pressure ≥130 mmHg or diastolic blood pressure ≥80 mmHg; Mean daytime baseline ABPM systolic blood pressure ≥130 mmHg or diastolic blood pressure ≥80 mmHg; Treating primary care clinician has independently determined that initiation of antihypertensive pharmacotherapy is clinically indicated; Either:; Not currently receiving antihypertensive therapy, OR; Receiving a single antihypertensive medication (ACE inhibitor, ARB, thiazide/thiazide-like diuretic, or calcium channel blocker) which the treating primary care clinician considers safe to discontinue for a 2-week washout period; Suppressed renin defined as direct renin concentration <6 ng/L (<10 mU/L) measured under routine outpatient conditions. Suppressed renin was selected as the primary biologic enrichment criterion because it is the physiologic hallmark of sodium-retaining, aldosterone-mediated hypertension and is more pragmatically scalable in primary care than complex biochemical primary aldosteronism (PA) definitions; In the opinion of the treating primary care clinician, outpatient participation in the study is appropriate.
Exclusion: Standardized office systolic blood pressure >170 mmHg if untreated OR >150 mmHg if receiving one antihypertensive medication; Pregnancy, breastfeeding, or intention to become pregnant during the study period. Women of childbearing potential must have a negative pregnancy test prior to randomization; Known secondary hypertension requiring disease-specific therapy; eGFR <30 mL/min/1.73 m2; Serum potassium ≥5.0 mmol/L; Serum sodium <135 mmol/L; Known diagnosis of PA requiring specialist-directed management; Current use of MR antagonists; Known intolerance or contraindication to spironolactone, candesartan, hydrochlorothiazide, or amlodipine; Participation in another interventional study likely to affect blood pressure; Inability to provide consent.