Increased Bioavailability of ?-Alanine by a Novel Controlled-Release Powder Blend Compared to a Slow-Release Tablet

Abstract

BACKGROUND: ?-Alanine is a sport supplement with increasing popularity due to its consistent ability to improve physical performance, with the downside of requiring several weeks of supplementation as imposed to the maximum daily and single dose tolerated without side effects (i.e., paresthesia). To date, the only alternative to overcome this problem has been use of a sustained-release tablet, while powders are the most commonly used format to deliver several grams of amino acids in a single dose. In this study we assessed the bioavailability, pharmacokinetics and paresthesia effect of ?-alanine after administration in a novel controlled-released powder blend (test) versus a sustained-release tablet (reference). METHODS: Twelve subjects (25.6 ± 3.2 y, 50% female) participated in a randomized, single-blind, crossover study. Each participant was administered orally the test (?-alanine 8 g, l-histidine 300 mg, carnosine 100 mg) or the reference product (10 tablets to reach ?-alanine 8 g, Zinc 20 mg) with a 1-week washout period. ?-Alanine plasma concentrations (0-8 h) were determined by LC-MS/MS and model-independent pharmacokinetic analysis was carried out. Paresthesia intensity was evaluated using a Visual Analog Score (VAS) and the categorical Intensity Sensory Score (ISS). RESULTS: The C(MAX) and AUC(0)(?)(?) increased 1.6- and 2.1-fold (both p < 0.001) in the test product, respectively, which yielded 2.1-fold higher bioavailability; K(a) decreased in the test (0.0199 ± 0.0107 min(-1)) versus the reference (0.0299 ± 0.0121 min(-1)) product (p = 0.0834) as well as V/F and Cl/F (both p < 0.001); MRT(0)(?last) increased in the test (143 ± 19 min) versus reference (128 ± 16 min) formulation (p = 0.0449); t(1/2) remained similar (test: 63.5 ± 8.7 min, reference: 68.9 ± 9.8 min). Paresthesia E(MAX) increased 1.7-fold using the VAS (p = 0.086) and the ISS (p = 0.009). AUEC increased 1.9-fold with the VAS (p = 0.107) and the ISS (p = 0.019) reflecting scale intrinsic differences. Pharmacokinetic-pharmacodynamic analysis showed a clockwise hysteresis loop without prediction ability between C(MAX), AUC(0)(?)(?) and E(MAX) or AUEC. No side effects were reported (except paresthesia). CONCLUSIONS: The novel controlled-release powder blend shows 100% higher bioavailability of ?-alanine, opening a new paradigm that shifts from chronic to short or mid-term supplementation strategies to increase carnosine stores in sports nutrition.