Glutathione

The Glutathione evidence base cited here is 8 sources — 2 clinical, 4 review. Its strongest evidence is human — 2 clinical studies, most recently 2009 ("Randomized, Double-Blind, Pilot Evaluation of Intravenous Glutathione in…"). Regulatory status: FDA-approved (oral/IV forms).

• Glutathione (GSH) is the body's 'master antioxidant' — a tripeptide (glutamate-cysteine-glycine) present in virtually every cell, central to neutralizing free radicals, detoxification, and recycling vitamins C and E.
• Its levels decline with age and are depleted by stress, toxins, and disease; injectable forms exist mainly to bypass glutathione's poor oral bioavailability.
• A key practical limitation: even IV glutathione has a very short plasma half-life (~14 minutes) and is rapidly broken down — so benefits depend on repeated dosing, not single shots, and brain uptake is limited without an intranasal route.

Glutathione is an endogenous tripeptide that functions as the cell's primary antioxidant and detoxifier. Because oral glutathione is poorly absorbed, it is given by injection (IV, IM, or sometimes subcutaneous) or intranasally in research and clinical settings to raise levels directly.

It is a prescription product, and everything below is research context rather than medical guidance.

Glutathione is a tripeptide of glutamate, cysteine, and glycine (~307 Da). Its defining chemistry is the cysteine sulfhydryl (-SH) group, which does the antioxidant work, and an unusual gamma peptide bond between glutamate and cysteine that protects it from most peptidases (ordinary peptide bonds would be cleaved faster).

It exists in a reduced (active, GSH) form and an oxidized (GSSG) form; the ratio of the two — typically >100:1 in healthy cells — is a core marker of cellular redox balance.

Glutathione directly neutralizes reactive oxygen species via its sulfhydryl group, conjugates toxins to make them water-soluble for excretion (Phase II detoxification), and regenerates oxidized vitamins C and E back to their active forms (the glutathione-ascorbate cycle). It also supports lymphocyte function in the immune system. The gamma bond's protease resistance is what lets it persist long enough to do this work intracellularly.

• Plasma half-life ~14 minutes — very short; rapidly converted to cysteine and other metabolites
• Intracellular half-life is longer than plasma
• Brain uptake is limited without an intranasal route

The ~14-minute plasma half-life is the honest limitation of injectable glutathione: it's a supportive therapy that benefits from repeated dosing, not a single-shot fix.

Glutathione is prescription-only; the figures below reflect clinical and research protocols and are context, not guidance.

• General antioxidant support: ~200–400 mg, 1–2× per week, IM or IV push
• Detox support: ~400–600 mg, 2–3× per week, IV
• Parkinson's research protocol: ~1,400 mg, 3× per week, IV infusion
• Maintenance: ~200 mg weekly, IM or subcutaneous

• Most injectables come pre-mixed; if lyophilized, reconstitute per instructions and inspect (clear to slightly yellow).
• pH matters for comfort — quality formulations are buffered to ~6.0–7.0; poorly buffered product stings on injection.
• Use the reduced (GSH) form, not oxidized (GSSG). Refrigerate at 2–8°C, protect from light, do not freeze.

Generally well-tolerated; injection-site stinging is common if the pH isn't balanced. Rare but serious events include anaphylaxis (especially IV) and potential hepatotoxicity at high doses. Other cautions: may worsen asthma (avoid inhaled forms), long-term use may lower zinc (consider supplementation), and there is a hemolysis risk in G6PD deficiency at high doses. Do NOT use during chemotherapy without oncologist approval (it can interfere with some agents), and avoid in pregnancy/breastfeeding. The Philippine FDA issued a warning about IV glutathione used for cosmetic skin-lightening.

• High-dose IV PK (Aebi et al., human): 2 g/m² IV raised plasma levels but confirmed the ~14-minute half-life and rapid conversion to metabolites.
• Parkinson's / substantia nigra (human post-mortem): ~40% GSH reduction in the substantia nigra of PD patients, linking glutathione depletion to oxidative stress in the disease.
• Intranasal glutathione Phase IIb (Mischley et al., 45 PD patients, 3 months): increased brain glutathione with mild motor improvement (placebo also improved).

Glutathione is a prescription product. Research-grade material sold outside that channel is unregulated; use happens without quality oversight.

All citations link to the original source (PubMed, journal site, or regulatory filing). Independent research database — no vendor influence on what's cited.