Creatine monohydrate (
creatine) has potential neuroprotective properties and is a commonly used supplement in
amyotrophic lateral sclerosis (ALS) and other
neurodegenerative disorders. Minimum therapeutic and maximum tolerated dosages of
creatine are not yet known, nor is it known what systemic plasma concentrations result from specific dosage regimens. The objectives of this study were to establish steady-state plasma pharmacokinetics of
creatine at several dosages, and to evaluate the effects of
creatine on brain metabolites using
proton magnetic resonance spectroscopy ((1)H-MRS). Six participants with ALS received
creatine at three weekly escalating oral dosages (5, 10, and 15 g b.i.d.). Plasma
creatine levels and MR spectra were obtained at baseline and with each dosage increase. Mean pre-dose steady-state
creatine plasma concentrations were 20.3, 39.3, and 61.5 ug/ml at 5, 10, and 15 g b.i.d., respectively.
Creatine spectra increased by 8% (p = 0.06) and
glutamate +
glutamine signals decreased by 17% (p = 0.039) at higher dosages. There were no safety concerns at any of the dosages. In conclusion,
creatine plasma concentrations increased in a dose-dependent manner.
Creatine appears to cross the blood-brain barrier, and
oral administration of 15 g b.i.d. is associated with increased in vivo brain
creatine concentrations and decreased
glutamate concentrations.