Efficacy of Amlodipine-folic Acid Tablets on Reduction of Blood Pressure and Plasma Homocysteine

Traditional risk factors are estimated to account for only part of cardiovascular disease (CVD) risk. Non-traditional risk factors such as increased homocysteine concentration are believed to be causally related to CVD. The interactive effect between hypertension and hyperhomocysteinemia on the risk of CVD has received great attention. Methylenetetrahydrofolate reductase (MTHFR) was the main regulatory enzymes for homocysteine metabolism. MTHFR converts 5, 10-methylene-THF into 5-methyl-THF. Polymorphism of MTHFR C677T leads to a reduction in enzyme activity, which may lead to an increased concentration of plasma homocysteine and lower levels of serum folate, particularly in those with low folate intake. In the present study, we sought to assess: (1) the efficacy and safety of Amlodipine-folic Acid Tablets in lowering blood pressure and homocystein in patients with mild to moderate hypertension and hyperhomocysteinemia (hcy≥10μmol/L);(2) if the blood pressure and homocysteine-lowering efficacy of Amlodipine-folic Acid Tablets can be modified by individual methylenetetrahydrofolate reductase (MTHFR) C677T polymorphisms.

In all, about 756 patients with mild or moderate hypertension and hyperhomocysteinemia will be recruited from about 18 hospitals in different Chinese regions. All hospitals are certified as clinical pharmacology centers by the State Food and Drug Administration (SFDA) in China. Eligible subjects are randomly and double-blindly assigned to one of the three treatment groups: 1) amlodipine tablet (5 mg, control group); 2) amlodipine-folic acid tablet (5mg amlodipine combined with 0.4 mg of folic acid, low FA group); or 3) amlodipine-folic acid tablet (5 mg amlodipine combined with 0.8 mg of folic acid, high FA group), once daily for 8 weeks.

The allocation of participants was programmed by an independent statistical coordinating center, encrypted, and sent to each study center. Tablet containers were labeled only with the name of the trial and the allocated concealment number. The participants, care partners, and all staff directly involved in the trial were blinded to interventions during the period of the trial.

Demographic and clinical information were obtained at baseline. Blood pressure was examined at baseline and every two weeks for a total period of 8 weeks. Blood homocysteine and folate concentrations were examined at baseline and at 4 and 8 weeks of the trial. MTHFR C677T genotypes were determined for each study subject.

All analyses will be performed according to the principle of intention to treat.