Glycine (research-grade spray)
/ Endogenous non-essential amino acid; NMDA glycine-binding site agonistALIAS · Glycine (research-grade) · Aminoacetic acid
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Tier 2. Small randomised trials of oral glycine for sleep quality (Inagawa 2006) and adjunctive use in schizophrenia (Heresco-Levy 1999) form the strongest controlled human data; mechanistic interest in metabolic syndrome and longevity rests largely on rodent and observational data. Glycine is GRAS (Generally Recognized As Safe) for food use; specific spray or research-grade preparations sit outside FDA drug approval.
Glycine is the simplest amino acid (a single hydrogen as side chain) and the smallest of the proteinogenic amino acids. In the central nervous system it acts as both an inhibitory neurotransmitter (via strychnine-sensitive glycine receptors enriched in spinal cord and brainstem) and an obligatory co-agonist at the NMDA glutamate receptor (via the strychnine-insensitive glycine-B site on the GluN1 subunit). At the NMDA receptor, glycine binding is required alongside glutamate for channel opening, and partial saturation of the glycine-B site under physiological conditions provides a mechanistic rationale for adjunctive glycine in conditions of hypothesised NMDA hypofunction.
Peripherally, glycine participates in glutathione biosynthesis (as the glycine of the gamma-Glu-Cys-Gly tripeptide), porphyrin synthesis, creatine synthesis, and bile acid conjugation. Plasma glycine pharmacokinetics show rapid absorption with peak concentration approximately one hour after oral dosing.
Tier 2. Small randomised trials have evaluated oral glycine three grams before bed for subjective sleep quality (Inagawa and colleagues 2006), with reported improvements in fatigue and daytime sleepiness measures. Heresco-Levy and colleagues (1999) reported adjunctive high-dose glycine reduced negative symptoms in schizophrenia in a placebo-controlled crossover trial. Subsequent CONSIST trial (2007) and meta-analyses have produced mixed results in schizophrenia adjunct use.
Generally well-tolerated at gram-scale oral doses across the published trial literature. Reported adverse events include mild gastrointestinal upset and (at high doses) soft stools. The schizophrenia adjunct trials used 30-60 g/day with acceptable tolerability over weeks; very-long-term safety at these doses is not established.
Regulatory status
- FDA status:
- Not FDA-approved
The 'spray' presentation is a vendor format rather than a defined pharmaceutical product. Most published evidence uses oral powder or capsule. Long-term outcome data on geroscience or metabolic-syndrome endpoints are sparse and rest primarily on rodent and observational human data; randomised long-term outcome trials in healthy aging adults have not been published. Vendor positioning frequently extrapolates from the GlyNAC trial literature (combined glycine plus N-acetylcysteine) which is a different intervention.