Effect of the angiotensin-converting enzyme inhibitor perindopril on haemostasis in essential hypertension

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.

Molecular structure and stability of perindopril erbumine and perindopril L-arginine complexes

The methods of theoretical chemistry have been used to elucidate molecular properties of the antihypertensive, cardiovascular protective and antithrombotic perindopril ((2S,3aS,7aS)-1-[(2S)-2-[[(2S)-1-ethoxy-1-oxopentan-2-yl]amino]propanoyl]-2,3,3a,4,5,6,7,7a-octahydroindole-2-carboxylic acid). The geometries and energies of various neutral and ionized complexes of perindopril erbumine and perindopril l-arginine have been computed using HF/6-31G(d) and Becke3LYP/6-31G(d) methods. The calculations showed that in both, the isolated state and water solution perindopril erbumine exists as a neutral complex. In the gas-phase perindopril l-arginine both neutral and ionic complexes are, at the HF level of theory, almost equally stable. The B3LYP level of theory slightly favors single proton transfer complex perindopril l-arginine (by about 14 kJ mol(-1)). In polar solvents like water, the ionized form of perindopril l-arginine becomes much more favored. According to our calculations l-arginine is bound to perindopril more strongly (by about 25 kJ mol(-1)) than erbumine.

Acidity, lipophilicity, solubility, absorption, and polar surface area of some ACE inhibitors

Computational chemical methods have been used to correlate the molecular properties of the 10 ACE inhibitors (captopril, enalapril, perindopril, lisinopril, ramipril, trandolapril, quinapril, fosinopril, benazepril, and cilazapril) and some of their active metabolites (enalaprilat, perindoprilat, ramiprilat, trandolaprilat, quinaprilat, fosinoprilat, benazeprilat, and cilazaprilat). The computed pK a values correlate well with the available experimental values. In the dicarboxylic ACE inhibitors, the carboxyalkyl carboxylate group of the ACE inhibitors studied is more acidic than the C-terminal carboxylate. However, at physiological pH = 7.4 both carboxyl groups of ACE inhibitors are completely ionized and the dicarboxyl-containing ACE inhibitors behave as strong acids. The available experimental partition coefficients of these ACE inhibitors investigated are well reproduced by the neural network-based ALOGPs and the fragment-based KoWWiN methods. All parent drugs (and prodrugs), with the exception of fosinopril, are compounds with low lipophilicity. Calculated pK a, lipophilicity, solubility, absorption, and polar surface area of the most effective ACE inhibitors for the prevention of myocardial infarction, perindopril and ramipril, were found similar. Therefore, it is probable that the experimentally observed differences in the survival benefits in the first year after acute myocardial infarction in patients 65 years of age or older correlate closely to the physicochemical and pharmacokinetic characteristics of the specific ACE inhibitor that is used.

Combined therapy with ramipril and simvastatin has beneficial additive effects on tissue factor activity and prothrombin fragment 1+2 in patients with type 2 diabetes

Tissue factor (TF) plays a pivotal role in thrombus formation. Statins and angiotensin converting enzyme inhibitors attenuate expression of TF by distinct mechanism. Therefore, we hypothesized that combined therapy with simvastatin and ramipril may have additive beneficial anti-atherogenic effects to lower TF activity when compared with either drug alone. This was a randomized, double-blind, placebo-controlled cross-over trial with three treatment arms (each 2 months) and two washout periods (each 2 months). Fifty patients with type 2 diabetes were given simvastatin 20 mg and placebo, simvastatin 20 mg and ramipril 10 mg, or ramipril 10 mg and placebo daily during each treatment period. Simvastatin and ramipril monotherapy tended to reduce TF activity (0.53 to 0.46 nM, P=0.056; 0.54 to 0.50 nM, P=0.167, respectively) while combined therapy had a significant effect (0.64 to 0.43 nM, P<0.001). All three therapies significantly reduced prothrombin fragment 1+2 (F1+2) levels from their respective baselines (P=0.037, P<0.001, and P=0.057, respectively). Combined therapy significantly reduced TF activity and F1+2 levels to a greater extent than either simvastatin or ramipril alone (P=0.029 and P=0.040 by ANOVA, respectively). Percent changes in TF activity and percent changes in F1+2 levels were significantly correlated. All three therapies reduced CD40 ligand levels from their respective baselines (P=0.098, P<0.001, and P=0.002, respectively) with no significant differences among these three therapies (P=0.204 by ANOVA). Ramipril combined with simvastatin significantly reduces plasma TF activity and F1+2 levels to a greater extent than monotherapy with either drug in patients with type 2 diabetes.

New risk factors for atherosclerosis in hypertension: focus on the prothrombotic state and lipoprotein(a)

Although adequate control of blood pressure is of basic importance in cardiovascular prevention in hypertensive patients, correction of additional risk factors is an integral part of their management. In addition to classical risk factors, epidemiological research has identified a number of other conditions that might significantly contribute to cardiovascular risk in the general population and might achieve specific relevance in patients with high blood pressure. In fact, more than 20% of patients with premature cardiovascular events do not have any of the traditional risk factors and, although effective intervention on blood pressure and additional risk factors has significantly reduced cardiovascular morbidity and mortality, the contribution to stroke, coronary artery disease and renal failure is still unacceptably high. Evaluation of new risk factors may further expand our capacity to predict atherothrombotic events when these factors are included along with the traditional ones in the assessment of global cardiovascular risk in hypertensive patients. Because it could be anticipated that the role of these novel factors will become increasingly evident in the future, researchers with an interest in hypertension and physicians dealing with problems related to cardiovascular prevention should give them appropriate consideration. This review summarizes the basic biology and clinical evidence of two emerging risk factors that are reciprocally related and contribute to the development and progression of organ damage in hypertension: the prothrombotic state and lipoprotein(a).

Platelet aggregation, blood viscosity and serum lipids in hypertensive and obese children

A group of 35 patients (median age 15.5 years, range 8-17 years) with juvenile essential hypertension, 15 with body mass index (BMI kg/m(2)) <25 and 20 with BMI >25, as well as 35 age and sex matched controls (BMI <25 n=20; BMI >25 n=15) were investigated to study the role of hypertension and obesity, separately and in combination, on in vitro platelet aggregation, blood and plasma viscosity, plasma lipid concentrations and lipid peroxidation as well as nitric oxide (NO) production. Obese children (hypertensive and controls) had significantly higher concentrations of total cholesterol and triglycerides. The levels of high density lipoprotein (HDL)-cholesterol were lower in obese hypertensive children than their non-obese counterparts. There was a significant increase in platelet aggregation and a decrease in NO levels in hypertensive patients (obese and non-obese) reflecting a significant negative correlation (r=-0.553 and -0.530, n=35; P<0.01, respectively). However, an increased tendency to aggregation was also evident in obese normotensive patients. A significant positive correlation was observed between the platelet aggregation and BMI (r=0.501, n=35; P<0.01). Plasma free thiols were decreased in hypertensive children independent of their BMI. An increased lipid peroxidation and higher blood and plasma viscosity were found only in obese patients with hypertension. Multivariate analysis revealed significant interactions in the effects of obesity and hypertension on platelet aggregation and thiol oxidation.

CONCLUSION

in obese children an increased platelet aggregation and oxidative insult contribute to the development of hypertension and to the promotion of vascular damage.