Glutathione Nasal Spray

Reduced glutathione, GSH, is the tripeptide γ-glutamyl-cysteinyl-glycine, and it is the most plentiful thiol in mammalian cells outside of proteins. This listing is a metered nasal spray bottle holding 250 mg of GSH dissolved in sterile bacteriostatic water. Glutathione research ranges from its synthesis and turnover inside cells to its antioxidant role, and a smaller body of work asks what happens when it is delivered through the nose, including whether it reaches the brain.

What is in the bottle

The safety data sheet lists 250 mg of reduced glutathione per bottle, at no more than 2.5% w/v, in bacteriostatic water that contains 0.9% benzyl alcohol as an antimicrobial preservative, with sterile water making up the balance. In molar terms 250 mg of a 307.3 Da tripeptide is about 0.81 mmol. Glutathione itself is not classified as hazardous. Benzyl alcohol is listed as harmful if swallowed or inhaled, a serious eye irritant and a possible skin sensitiser.

The free thiol on the cysteine can oxidise to the disulfide form, GSSG, so keep the bottle closed: upright and capped at 2 to 8 °C, away from light, and never frozen. The same tripeptide is sold as a dry solid in the glutathione 1500 mg vial, which stays dry until the lab dissolves it.

What the research covers

Every mammalian tissue makes glutathione, and Lu's review placed it at the centre of the cell's defence against oxidative stress and of redox signalling¹. Its production is limited by two things, the cysteine supply and the activity of glutamate cysteine ligase, an enzyme whose genes respond to Nrf2 and other transcription factors¹. The breakdown side has been revised more recently: a 2018 review argued that findings on glutathione transport and degradation contradict much of the γ-glutamyl cycle that textbooks have taught since 1970².

The nasal format rests on a separate question. Illum's 2002 review of nasal drug delivery discussed the finding that some drugs travel straight from nose to brain by the olfactory pathway, and gave proof-of-concept examples in humans³. Glutathione was not among the drugs it studied. The glutathione-specific work, summarised in the glutathione routes guide, comes almost entirely from one research group: an open-label imaging study reported a rise in brain glutathione after nasal delivery, and a later placebo-controlled trial in Parkinson's disease found no advantage over placebo.

The guide also notes that no human plasma data exist for intranasal glutathione, so how much of a spray is absorbed, and where it goes, is not established. None of these studies used this product.

Frequently asked questions

References

1. Lu SC. Glutathione synthesis. Biochim Biophys Acta. 2013;1830(5):3143-53. DOI · PubMed
2. Bachhawat AK, Yadav S. The glutathione cycle: Glutathione metabolism beyond the γ-glutamyl cycle. IUBMB Life. 2018;70(7):585-592. DOI · PubMed
3. Illum L. Nasal drug delivery: new developments and strategies. Drug Discov Today. 2002;7(23):1184-9. DOI · PubMed