Patient description: A 72-year-old man complains of increasing calf pain when walking uphill. The symptoms have gradually increased over the past 3 months. The patient had an uncomplicated myocardial infarction 2 years earlier and a transient ischemic attack 6 months ago. Over the past month, his blood pressure has worsened despite previous control with diltiazem, hydrochlorothiazide, and propranolol. His is currently taking isosorbide dinitrate, hydrochlorothiazide, and aspirin. On physical examination, his blood pressure is 151/91 mm Hg, and his pulse is 67/min. There is a right carotid bruit. His lower extremities are slightly cool to the touch and have diminished pulses at the dorsalis pedis.

Clinical trial eligibility criteria: eligible ages (years): 18.0-999.0,  Hypertension Patients who are eligible and able to participate in the study, and who give written informed consent before any assessment is performed Men or women 18 years and older of African American background; self identified Patients with stage 2 hypertension. Patients must have a MSSBP ≥ 160 mmHg and < 200 mmHg at Visit 5 (randomization)  Office blood pressure measured by cuff (MSSBP ≥ 200 mmHg and/or MSDBP ≥ 110 mmHg) at any visit Use of other investigational drugs at the time of enrollment, or within 30 days or 5 half-lives whichever is longer History of hypersensitivity to any of the study drugs or to drugs belonging to the same therapeutic class (CCBs or thiazide diuretics) as the study drugs Long QT syndrome or QTc > 450 msec for males and > 470 msec for females at screening History of malignancy of any organ system (other than localized basal cell carcinoma of the skin), treated or untreated, within the past 5 years, regardless of whether there is evidence of local recurrence or metastases Pregnant or nursing (lactating) women, where pregnancy is defined as the state of a female after conception and until the termination of gestation, confirmed by a positive hCG laboratory test (> 5 mIU/mL) Women of child-bearing potential, defined as all women physiologically capable of becoming pregnant. including women whose career, lifestyle, or sexual orientation precludes intercourse with a male partner and women whose partners have been sterilized by vasectomy or other means, they are using two birth control methods. The two methods can be a double barrier method or a barrier method plus a hormonal method Adequate barrier methods of contraception diaphragm, condom (by the partner), intrauterine device (copper or hormonal), sponge or spermicide. Hormonal contraceptives any marketed contraceptive agent that includes an estrogen and/or a progestational agent. Reliable contraception should be maintained throughout the study and for 7 days after study drug discontinuation Women are considered post-menopausal and not of child bearing potential if they have had 12 months of natural (spontaneous) amenorrhea with an appropriate clinical profile (e.g. age appropriate, history of vasomotor symptoms) or six months of spontaneous amenorrhea with serum FSH levels > 40 mIU/mL [and estradiol < 20 pg/mL] or have had surgical bilateral oophorectomy (with or without hysterectomy) at least six weeks ago. In the case of oophorectomy alone, only when the reproductive status of the woman has been confirmed by follow up hormone level assessment History or evidence of a secondary form of hypertension