Valsartan 160 mg/Amlodipine 5 mg Combination Therapy versus Amlodipine 10 mg in Hypertensive Patients with Inadequate Response to Amlodipine 5 mg Monotherapy

Background and Objectives: When monotherapy is inadequate for blood pressure control, the next step is either to continue monotherapy in increased doses or to add another antihypertensive agent. However, direct comparison of double-dose monotherapy versus combination therapy has rarely been done. The objective of this study is to compare 10 mg of amlodipine with an amlodipine/valsartan 5/160 mg combination in patients whose blood pressure control is inadequate with amlodipine 5 mg. Subjects and Methods: This study was conducted as a multicenter, open-label, randomized controlled trial. Men and women aged 20-80 who were diagnosed as having hypertension, who had been on amlodipine 5 mg monotherapy for at least 4 weeks, and whose daytime mean systolic blood pressure (SBP) ${\geq}135mmHg$ or diastolic blood pressure $(DBP){\geq}85mmHg$ on 24-hour ambulatory blood pressure monitoring (ABPM) were randomized to amlodipine (A) 10 mg or amlodipine/valsartan (AV) 5/160 mg group. Follow-up 24-hour ABPM was done at 8 weeks after randomization. Results: Baseline clinical characteristics did not differ between the 2 groups. Ambulatory blood pressure reduction was significantly greater in the AV group compared with the A group (daytime mean SBP change: $-14{\pm}11$ vs. $-9{\pm}9mmHg$, p<0.001, 24-hour mean SBP change: $-13{\pm}10$ vs. $-8{\pm}8mmHg$, p<0.0001). Drug-related adverse events also did not differ significantly (A:AV, 6.5 vs. 4.5 %, p=0.56). Conclusion: Amlodipine/valsartan 5/160 mg combination was more efficacious than amlodipine 10 mg in hypertensive patients in whom monotherapy of amlodipine 5 mg had failed.