Effects of aliskiren, a renin inhibitor, on biomarkers of platelet activity, coagulation and fibrinolysis in subjects with multiple risk factors for vascular disease

Potential Protective Role of Blood Pressure-Lowering Drugs on the Balance between Hemostasis and Fibrinolysis in Hypertensive Patients at Rest and During Exercise

In patients with hypertension, the triad represented by endothelial dysfunction, platelet hyperactivity, and altered fibrinolytic function disturbs the equilibrium between hemostasis and fibrinolysis and translates into a hypercoagulable state, which underlies the risk of thrombotic complications. This article reviews the scientific evidence regarding some biological effects of antihypertensive drugs, which can protect patients from the adverse consequences of hypertensive disease, improving endothelial function, enhancing antioxidant activity, and restoring equilibrium between hemostatic and fibrinolytic factors. These protective effects appear not to be mediated through blood pressure reduction and are not shared by all molecules of the same pharmacological class.

Effect of aliskiren and valsartan combination versus aliskiren monotherapy on hemostatic biomarkers in hypertensive diabetics: Aliskiren and Valsartan Impact in Diabetics pilot trial

Valsartan is known to inhibit platelet activity in both in vitro and ex vivo clinical setting, whereas aliskiren in vitro modulates antithrombin-III in plasma. The authors tested how aliskiren and valsartan combination versus aliskiren monotherapy will affect hemostatic biomarkers in mild-to-moderate hypertensive diabetics in the frame of the Aliskiren and Valsartan Impact in Diabetics (AVID) trial. A total of 52 patients with type 2 diabetes and mild-to-moderate hypertension were equally randomized to aliskiren (150-300 mg/d) and valsartan (160 mg/d) versus aliskiren (150-300 mg/d) alone for 4 weeks. A total of 25 biomarkers were serially measured, of which 16 are related to platelet function, 6 to coagulation, and 3 to fibrinolysis. Aliskiren monotherapy has no significant impact on any of the assessed biomarkers. In contrast, valsartan on top of aliskiren provided significant inhibition of ADP-induced platelet aggregation (P=0.032), decreased shear-induced activation measured with PFA-100 analyzer (P=0.041), and diminished expression of GP IIb/IIIa activity (P=0.027) measured by PAC-1 antibody, GP Ib (CD42b, P=0.033), vitronectin receptor (CD51/61, P=0.046), P-selectin (CD62p, P=0.026), lysosome-associated membrane protein (CD107a, P=0.042), and CD40-ligand (CD154, P=0.048). In AVID trial, valsartan in combination with aliskiren mildly but significantly inhibited platelets, confirming previous observations. In contrast, aliskiren monotherapy does not enhance antithrombin activity, suggesting that previous data probably represent a laboratory artifact. Importantly, these randomized data were generated on top of low-dose daily aspirin, supporting extra benefit for combination use of angiotensin receptor blockers and renin inhibitors in high-risk diabetic population.