Effect of oral pyridoxine hydrochloride supplementation on in vitro platelet sensitivity to different agonists.

Effect of vitamin B6 (pyridoxine-HCl, CAS 58-56-0) on platelet aggregation, plasma lipids and serum zinc level was investigated. The trial comprised 24 healthy male volunteers, aged between 19-24 years. The subjects were randomized in two groups of 12 and treated for 4 weeks by a single daily oral dose of 5 mg/kg vitamin B6 or placebo. Pyridoxine inhibited ADP- or epinephrine-induced aggregation by 48% and 41% (p < 0.001), respectively, whereas there was no change in control group. No significant effect on either, bleeding time, coagulation time or on platelet count was demonstrated in subjects given placebo. Pyridoxine prolonged both bleeding and coagulation time but not over the physiological limits. It had no effect on platelet count. These observations strongly suggest that vitamin B6, with no effect on platelet count, not only inhibits platelet aggregation but also prolongs clotting time. Pyridoxine significantly reduced total plasma lipid and cholesterol levels, whereas it enhanced HDL-cholesterol level. Serum zinc level was also significantly increased by pyridoxine (p < 0.001). These findings suggest that oral vitamin B6 inhibits platelet aggregation in normal subjects.