9.9 Aliskiren, a Novel Renin Inhibitor, is Well Tolerated and Has Sustained BP-Lowering Effects Alone or in Combination with HCTZ During Long-Term (52 Weeks) Treatment of Hypertension

Introduction: The long-term efficacy and tolerability of the novel potent renin inhibitor aliskiren, with optional addition of hydrochlorothiazide (HCTZ), were assessed in a 12-month, open-label study in patients with hypertension, including a randomised, placebo-controlled withdrawal period.

Methods: Patients with mean sitting diastolic blood pressure (MSDBP) 90–109 mmHg were randomised to aliskiren 150 mg (n=1178) or 300 mg (n=773) once daily, after washout and a 2–4 week drug-free period. Dose titration (aliskiren 150 mg titrated to 300 mg) or addition of HCTZ (12.5 mg titrated to 25 mg if required) to aliskiren 300 mg was permitted in patients with BP>140/90 mmHg after Month 2. A subgroup of patients remaining on aliskiren monotherapy at Month 11 were randomised to continued aliskiren (n=132) or placebo (n=129) during a 4-week double-blind withdrawal phase. MSDBP and mean sitting systolic BP (MSSBP) were measured at intervals throughout open-label treatment and withdrawal; ambulatory BP monitoring (ABPM) was performed in a subset of patients at the start and end of the withdrawal period.

Results: A total of 1625 patients (83%) completed the open-label treatment period. Mean BP reductions (MSSBP/MSDBP) at endpoint were 17.5/12.4 and 18.8/13.3 mmHg in aliskiren 150 and 300 mg groups, respectively. 868 patients (45%) required addition of HCTZ; BP reductions at study end were comparable in these patients (18.7/12.1 mmHg) and those responding adequately to monotherapy (17.4/13.3 mmHg). In the withdrawal period patients on placebo had a gradual increase in mean sitting BP, while BP reductions were maintained in patients remaining on aliskiren. At the end of the withdrawal period there was a statistically significant difference between the two groups (5.99/3.87 mmHg; p<0.0001 for MSSBP and MSDBP). ABPM at Month 12 also showed significantly increased BP with placebo versus continued aliskiren (treatment difference 4.14/3.87 mmHg; p<0.0001 for systolic and diastolic BP), with clear separation at most hourly timepoints. There was no evidence of dose-dependent side-effects during open-label treatment with aliskiren alone or with HCTZ. During the withdrawal period, AE rates were similar in patients on aliskiren (15.9%) and placebo (14.7%).

Conclusion: Aliskiren, as monotherapy and in combination with HCTZ, is effective and well-tolerated in the long-term treatment of hypertension. Aliskiren continues to demonstrate significant BP lowering efficacy, sustained over 24-hours, after 12 months’ treatment. Following treatment withdrawal, BP rose gradually with no evidence of rebound.