Fentanyl lasts for hours, while the effect of methadone can last much longer.(1,2,3) Prescription opioids are mainly used to treat acute pain (in the emergency department or after a surgical procedure), chronic pain, cancer-related pain, palliative care, and end-of-life care

Melanin biology = weeks to months Dose well below studied ranges (e.g., under 250mg) minimal supporting research at very low doses No ALA or NAC in formula these co-factors are commonly included to support glutathione regeneration, though not strictly mandatory No FSSAI number on label illegal in India Prices below 300/month raw material cost makes this difficult at consistent quality Clinical Research: What Studies Actually Show Rather than relying on marketing claims, here's a brief summary of the published research most relevant to oral glutathione and skin brightening: Oral glutathione and skin pigmentation Arjinpathana & Asawanonda (2012), Journal of Dermatological Treatment , found that subjects taking 500mg/day oral glutathione for 4 weeks showed a significant reduction in melanin index compared to placebo in a double-blind randomised trial
Eumelanin and pheomelanin lend our skin the tan (brown-colored complexion) and burns (red-hued complexion), respectively
PLoS ONE 11(2):e0148172 Markic J, Krzelj V, Markotic A, Marusic E, Stricevic L, Zanchi J, Sapunar A (2006) High incidence of glucose-6-phosphate dehydrogenase deficiency in Croatian island isolate: example from Vis island