Irbesartan Versus Amlodipine: The OBI Study

Double Blind Study of Irbesartan vs. Amlodipine in Obese Hypertensive Subjects- The OBI Study

Objective:

1. To study the effectiveness of irbesartan 300mg and amlodipine 10 mg in 24h ambulatory blood pressure values in obese subjects
2. To study the drug specific effect in arterial stiffness
3. To study possible drug mechanisms in obesity (reduction of central adiposity and changing the ratio of leptin to adiponectin)

Study Objectives

1. Primary:

   • Reduction of 24h BP in obese hypertensives
   • Reduction in arterial stiffness

2. Secondary

   • Drug specific effect on new onset of diabetes
   • Drug specific effect on reduction in central fat deposition and the leptin to adiponectin ratio

Study design

Study drugs: Irbesartan 300mg vs. amlodipine 10mg

Tx duration and follow-up: 12 months

Collected data:

• 24h SBP and DBP in time 0, 1, 12.
• Pulse wave velocity in time 0,1,12.
• Central obesity (total, visceral, abdominal fat) in time 0,1,12.
• Leptin/adiponectin in time 0,1,12.
• BMI, waist/hip ratio in time 0,1, 12.
• Glu, HbA1c, insulin in time 0, 1,12.
• K, Na, Cr, BUN, Chol, Tg, HDL, LDL,ALT, AST in time 0, 1,12. Number of patients: The reduction in mean SBP expected to be 15 mmHg. Previous studies from our group reported an 14mmHg SD for mean SBP. The sample size required at the two sided 5% significance level and 80% power is 40 patients (Lehr's formula)

Number of centers: 1

Inclusion Criteria:

1. Age between 18 and 60 years.
2. All patients are going to give their informed consent to participate in the study.
3. Stage I hypertension.
4. BMI > 30.

Exclusion Criteria:

1. Known oversensitiveness,
2. Chronic renal disease (GFR < 50 ml/min) or ESRD,
3. Heart or respiratory failure, OR
4. Recent MI, shock, liver deficiency (ALT or AST > 3 times normal and pregnancy or lactation.