Changing in Plasma Concentration of a New Form of Creatine

Overview

Creatine is one of the most popular supplements among athletes. Studies have consistently shown that creatine supplementation increases intramuscular creatine concentrations, improving exercise performance and/or enhancing training adaptations. Research has also indicated that creatine supplementation may improve post-exercise recovery and may help with injury prevention, thermoregulation, rehabilitation, and neuroprotection in cases of concussion and/or spinal cord injury. Several clinical applications of creatine supplementation have also been investigated, particularly in relation to neurodegenerative diseases (e.g., muscular dystrophy, Parkinson's disease, and Huntington's disease), diabetes, osteoarthritis, fibromyalgia, aging, cerebral and cardiac ischemia, adolescent depression, and pregnancy. The most commonly studied form of creatine in the literature is creatine monohydrate. The uptake of creatine first involves its absorption into the bloodstream and subsequently its uptake by target tissues. Plasma creatine levels typically peak about 60 minutes after the oral ingestion of creatine monohydrate. An initial increase in plasma creatine levels, followed by a reduction, can indirectly suggest increased creatine uptake by target tissues. However, in recent years, new formulations of creatine have been developed to improve its solubility, stability, or bioavailability. Therefore, it is of interest to evaluate whether these formulations differ in absorption kinetics from creatine monohydrate, the reference form in the literature. The aim is to compare the blood absorption of a new formulation of creatine (containing Creatine Phosphate, Creatine Pyruvate, Creatine Hydrochloride) with that of traditional creatine monohydrate. It is hypothesized that the new formulation has a pharmacokinetic profile similar to that of creatine monohydrate.

Participants will arrive at the laboratory after an overnight fast (8-10 h), having consumed their last meal no later than 20:00 h on the previous day. They will be instructed to refrain from any structured physical training within 48 h prior to the study and to abstain from alcohol and caffeine from 20:00 h on the previous day. During the entire experimental session, no food, caffeine or caloric beverages will be allowed. Water intake will be standardized within predefined limits (250 mL prior to baseline and up to 700 mL during the session). Creatine, both new formulation and standard, will be administered dissolved in water, and no additional fluids will be allowed for at least 20 min following ingestion to minimize variability in gastrointestinal absorption. Creatine monohydrate will be administered orally as a single dose (5 g) and the new formulation as a single dose (10g), both dissolved in 200 mL of water. The exact time of ingestion will be recorded and defined as time zero (T0). Blood samples for plasma analysis will be collected at baseline and at 30, 60, 90, 120, and 180 minutes following creatine administration, in accordance with previously published protocols (Jäger et al., 2007; Harris et al., 2004). Participants will remain seated for at least 10 minutes before each blood draw. Venous blood will be collected from an antecubital vein into EDTA-containing tubes. Blood samples will be centrifuged within 30 min of collection at 2,000 rcf for 15 min at 4°C. Plasma will be carefully aliquoted into pre-labeled microtubes and will be stored at -80°C until analysis. All samples from the same participant will be analyzed in the same analytical run to minimize inter-assay variability. Then, participants who took the new formulation will be switched with the standard and vice versa.