Losartan Versus Hydrochlorothiazide in Reversing Remodeling of Small Arteries in Pre-Hypertensive Pre-Diabetic Subjects

This randomized, double-blind, parallel group, two-centre pilot study will test the hypothesis that subjects who are otherwise healthy but fulfill the criteria for a diagnosis of pre-hypertension and pre-diabetes will have regression or reduced progression of hypertension-associated changes in their resistance arteries if their blood pressure is controlled for 6 months with losartan, whereas similar subjects whose blood pressure is equally well controlled using hydrochlorothiazide will have significantly less improvement of the changes in their resistance arteries.

The study will be conducted by Dr. Ernesto Schiffrin at the Cardiovascular Prevention Center, Sir Mortimer B. Davis Jewish General Hospital, McGill University, in Montreal, in association with a co-investigator at a second site, Dr. Rhian M. Touyz at the Ottawa General Hospital's Hypertension Clinic at the Riverside Campus and Kidney Research Center (University of Ottawa/Ottawa Health Research Institute). Over the past 15 years, Dr. Schiffrin has developed the gluteal subcutaneous biopsy methodology to be applied in the study. The technique has been practiced for many years (15 years) by Dr. Schiffrin, who more recently has collaborated with Dr. Touyz who used the technique together with Dr. Schiffrin before moving to Ottawa in 2005. In addition, stiffness of aorta (carotid-femoral pulse wave velocity) and endothelium-dependent hyperemic responses will be evaluated. Dr. Schiffrin and Dr. Touyz will be responsible for patient recruitment, data collection and analysis, and maintenance of study charts and patient records. Merck-Frosst Canada Ltd (MFCL) will be responsible for the study budget and the supply of medication.

The study subjects (men or women, 25 to 70 years of age) will be divided into two groups. Individuals with pre-hypertension (blood pressure = 120-139/85-90 mmHg) will be double-blindly allocated to either losartan or hydrochlorothiazide therapy respectively in groups 1 and 2. Study subjects will be assessed for their compatibility with inclusion and exclusion criteria, and subjects meeting the criteria will undergo baseline biopsies of gluteal subcutaneous resistance vessels. In addition, stiffness of aorta (carotid-femoral pulse wave velocity) and finger endothelium-dependent hyperemic responses will be evaluated. Subjects in each treatment group will receive antihypertensive therapy for 6 months, to control their blood pressure to 100-120/70-80 mmHg, and then have repeat gluteal biopsies, aortic stiffness and endothelial function measurements. The media/lumen ratio of resistance arteries 150-300 um in lumen diameter in the biopsied tissues will be determined. Previous work (1-3) has shown this parameter to be a useful marker of hypertensive vascular disease which may be modified by treatment with antihypertensive agents, particularly blockers of the renin-angiotensin system.

Subjects will give informed consent, and be medically assessed to determine whether they satisfy the inclusion and exclusion criteria. Eligible subjects will have a sitting systolic blood pressure (SiSBP) 120-139 mmHg, and be otherwise in good health. Eligible subjects will have a gluteal biopsy, and then be randomized to treatment group 1 or group 2 for 6 months.

For study purposes, SiSBP will be defined as the average of three consecutive valid readings, taken at one-minute intervals after five minutes of repose.

Thirty subjects who satisfy the study criteria will be randomized to receive once daily therapy with either losartan 50 mg or hydrochlorothiazide 12.5 mg. Subjects will take study medication once daily between 06:30 and 11:00, and be followed up in morning clinic visits, scheduled between 06:30 and 11:00. Subjects will be instructed not to take their medication on the morning of clinic visits until after the clinic evaluations have been completed. During the 6 months of treatment, subjects will have their "trough" blood pressure, heart rate (HR) and body weight measured at every clinic visit. At visits where laboratory safety tests will be done, subjects will be asked to come fasting.

All subjects will be force-titrated to losartan 100mg daily or hydrochlorothiazide 25 mg daily. However, if they develop dizziness and/or SiBPs below 100/70 mmHg, the dose may be down-titrated back to 50 mg losartan or 12.5 mg hydrochlorothiazide.

If any subjects develops SiBPs > 139/90 mmHg, open label amlodipine will be give to maintain SiBP < 139/90 mmHg, attempting however to reach the goal of SiSBP < 120 mmHg. Amlodipine will be started at a dose of 2.5mg daily and up-titrated every 4 weeks to 5 mg daily and then to 10 mg daily. As long as SiBP < 139/90 mmHg, subjects will not be discontinued from the study. Subjects whose hypertension is not adequately controlled (SiBP > 139/90 mmHg) with addition of amlodipine up-titrated to 10 mg daily, however, will be discontinued from the study.

Laboratory safety tests will be done at Weeks 4, 12, 24 of double-blind therapy (Visits 6, 8 and 9). An ECG will be repeated at the end of the study (Week 24).

The study will start at the end of 2006, last approximately 1 year. Recruitment should be completed within 6-9 months. Duration of other periods has been specified briefly above within the protocol.