A Comparative Evaluation of Amlodipine and Hydrochlorothiazide as Monotherapy in the Treatment of Isolated Systolic Hypertension in the Elderly C. Calvo, 1 F. Gude, 1 J. Abellán, 2 J. Oliván, 3 M. Olmos, 4 L. Pita, 5 D. Sánz, 6 J. Sarasa, 7 J. Bueno, 8 J. Herrera, 9 J. Macías, 10 T. Sagastagoitia, 11 B. Ferro, 12 A. Vega 12 and J. Martínez 12 1 Hypertension Unit and Epidemiology Department, Hospital Clínico Universitario, Santiago de Compostela, Spain 2 Murcia S. Andrés Primary Care Center, Murcia, Spain 3 Hypertension Unit, Hospital Virgen Macarena, Seville, Spain 4 Department of Nephrology, Hospital Universitario La Fe, Valencia, Spain 5 Department of Internal Medicine, Hospital Universitario Santa Cristina, Madrid, Spain 6 Department of Clinical Nephrology, Clínica Puerta de Hierro, Madrid, Spain 7 Department of Preventive Medicine, Hospital Miguel Servet, Zaragoza, Spain 8 Department of Internal Medicine, Hospital Clínico Universitario, Zaragoza, Spain 9 Department of Nephrology, Hospital Central de Asturias, Oviedo, Spain 10 Department of Nephrology, Hospital Clinico, Salamanca, Spain 11 Department of Cardiology, Hospital Civil de Basurto, Bilbao, Spain 12 Medical Division, Pfizer, S.A., Madrid, Spain Abstract Objective: The purpose of this 8-week, randomised, single-blind, parallel group, multicentre, comparative study was to evaluate the efficacy, safety and tolera- bility of the dihydropyridine calcium antagonist amlodipine versus the thiazide diuretic hydrochlorothiazide for control of isolated systolic hypertension (ISH) in elderly patients aged 60 years or more. Design: This was a phase IV, multicentre, single-blind, comparative, parallel group, randomised clinical trial, divided into two phases. Setting, Patients and Interventions: Following a 4-week placebo wash-out period (phase I), outpatients aged 60 to 87 years with systolic blood pressure (SBP) ≥ 160mm Hg and diastolic blood pressure (DBP) ≤ 95mm Hg were randomised to receive amlodipine 5 mg/day or hydrochlorothiazide 50 mg/day for 8 weeks (phase II). After 4 weeks of active treatment, if sitting SBP (sSBP) still was above 150mm Hg, the dose had to be doubled. Demographic and safety data were assessed in all patients and efficacy only in the evaluable patients according to pre-specified criteria. Results: 197 patients (66.5% women) were assigned to received amlodipine (n = 97) or hydrochlorothiazide (n = 100). 86 patients treated with amlodipine and 98 patients treated with hydrochlorothiazide were considered evaluable for CLINICAL USE Clin Drug Invest 2000 May; 19 (5): 317-326 1173-2563/00/0005-0317/$20.00/0 © Adis International Limited. All rights reserved.