Under construction – not a live service
Sign in
Not yet taking people in CanadaPhase 4

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.

Key facts

Who runs it
Ottawa Hospital Research Institute
Where
Laval, Ottawa, and Saint Isidore, CanadaSee the 4 sites
Trial code
Registry title
SPIRO-First: A Pragmatic Primary Care-Embedded Pilot Trial of Renin-Guided First-Line Antihypertensive Therapy
Status
Not yet recruiting
Phase
Phase 4
People taking part
30 people, planned
Starts
1 Jan 2027
Expected to end
Dec 2028
Type of study
Interventional, 2 groupsOne group gets an existing treatment, for comparison.
Treatments tested
  • Spironolactone (drug)
  • Candesartan 8mg
  • Hydrochlorothiazide (HCTZ) 25 milligrams.
  • Amlodipine (5mg)
Record updated
14 October 2026

Who can take part

AI summary

From the trial's eligibility criteria. Machine-read from the registry text on this page, so it can be wrong. The registry text below and the trial team decide who can take part.

The trial is looking for adults with high blood pressure and low renin, a blood hormone. A primary care clinician in Ontario must care for them and must have decided to start blood pressure medicine.

Age
18 years or older.
Sex
All sexes can join.
Disease stage
High blood pressure. In the office, the top number (systolic) must be ≥130 mmHg or the bottom number (diastolic) ≥80 mmHg. The daytime average from ambulatory blood pressure monitoring (ABPM, a home monitor worn through the day) must also be systolic ≥130 mmHg or diastolic ≥80 mmHg.
Earlier treatment
People can join if they take no blood pressure medicine now. They can also join if they take one medicine (ACE inhibitor, ARB, thiazide/thiazide-like diuretic, or calcium channel blocker). Their clinician must consider it safe to stop it for 2 weeks. People taking MR antagonists now cannot join.
Biomarker or test result
Low (suppressed) renin: direct renin concentration <6 ng/L (<10 mU/L) on a routine outpatient blood test.

Main reasons for not taking part

  • Office systolic blood pressure >170 mmHg without treatment, or >150 mmHg while taking one blood pressure medicine.
  • Known primary aldosteronism (PA) needing specialist care, or another known cause of high blood pressure needing its own treatment.
  • Current use of MR antagonists, or known intolerance or a reason not to take spironolactone, candesartan, hydrochlorothiazide, or amlodipine.
  • Kidney function eGFR <30 mL/min/1.73 m2, blood potassium ≥5.0 mmol/L, or blood sodium <135 mmol/L.
  • Pregnancy, breastfeeding, or plans to become pregnant during the study.

The registry criteria, word for word

Show all 19 criteriaShow less

Who can take part

  • 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

Who cannot take part

  • 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

Where in Canada

  • GMF Universitaire LavalLaval, CanadaContact: Rémi Goupil, MDNo longer taking part
  • Ottawa Nurse Practitioner-Led ClinicOttawa, CanadaContact: Hoda Mankal, NPNo longer taking part
  • The Ottawa HospitalOttawa, CanadaContact: Gregory L Hundemer, MDNo longer taking part
  • St-Isidore MédicalSaint Isidore, CanadaContact: Manon Denis-LeBlanc, MDNo longer taking part

About the trial

What the trial wants to find out

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

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.

The 2 groups in the trial

  • SpironolactoneTreatment being tested

    Spironolactone 25 mg daily

    Treatment: Spironolactone (drug)

  • Standard first-line antihypertensive therapyExisting treatment, for comparison

    Participants randomized to standard therapy will undergo secondary randomization to candesartan (8 mg daily), hydrochlorothiazide (25 mg daily), or amlodipine (5 mg daily)

    Treatment: Candesartan 8mg, Hydrochlorothiazide (HCTZ) 25 milligrams., and Amlodipine (5mg)

Questions to ask the study team

  1. How often do I need to come in, and for how long each time?
  2. Are travel costs paid?
  3. Can I keep my own doctor?
  4. What happens if I want to stop?

Contact the study team: see the registry record → Contacts and Locations

Print a page for my doctor

Data and sources

Registry record
Listed on ClinicalTrials.gov.
Official title
SPIRO-First: A Pragmatic Primary Care-Embedded Pilot Trial of Renin-Guided First-Line Antihypertensive Therapy
Plain-language title
Spironolactone compared with usual first blood pressure medicines in low-renin hypertensionGenerated from the registry record. The registry title is the official one.
AI summary
From the trial's eligibility criteria. Read by machine on 12 November 2026.
Record updated
14 October 2026