A Review of the Single-Dose Pharmacokinetics of Different Delivery Forms of Inositol-Stabilized Arginine Silicate (Nitrosigine®) in Healthy Males

The purpose of this review is to evaluate the pharmacokinetics of arginine absorption in healthy adult males taking inositol-stabilized arginine silicate (ASI; Nitrosigine®) in different delivery forms. Previous studies have evaluated ASI, showing it to be a readily absorbed form of arginine, bioavailable for an extended period of time, and efficacious at increasing blood flow. This study looks to compare the pharmacokinetics of ASI when consumed orally as a capsule, tablet, or beverage. The results of three (3) pharmacokinetic studies were evaluated: one using ASI capsules, one using ASI tablets, and one using an ASI beverage. In all studies, healthy males aged 18–40 were enrolled with a BMI of 18–30 kg/m2. In the ASI capsule study, ten participants were given three 500 mg ASI capsules (total of 1,500 mg/day). In the ASI tablet study, ten participants were given three 500 mg ASI tablets (total of 1,500 mg/day). In the ASI beverage study, 16 participants were given 1,500 mg of ASI in a beverage. For all studies, fasting blood samples were collected pre-dose and 0.5, 1, 1.5, 2, 3, 4, 5, and 6 hours post-dose, and analyzed for arginine content. The pharmacokinetics of arginine absorption were similar for all three dose formulations. There were significant increases in plasma arginine levels at 0.5 hours, which was the first post dose blood draw. All three ASI formulations had a similar arginine time of maximum concentration (tMax), with the beverage being the fastest at 0.6 ± 0.2 hours, followed by ASI tablets at 1.05 ± 0.50 hours, and ASI capsules at 1.13 ± 0.52 hours. All three ASI formulations demonstrated extended duration of increased arginine plasma levels with significant levels above baseline detected 5 to 6 hours after dosing. These data show that inositol-stabilized arginine silicate (Nitrosigine®), when used in these delivery forms, increases plasma arginine levels in as early as 0.5 hours (first timepoint tested), lasting up to 6 hours. This work was supported by Nutrition 21, LLC.