Is Metreleptin legal in the United Kingdom?

Transformative in people who make almost no leptin, and useless for ordinary obesity. The clearest case on this site of a hormone that only works as replacement.

When leptin was discovered in 1994, an obesity cure looked imminent: here was the hormone that tells the brain how much fat exists, and obese mice lacking it lost weight dramatically when given it back. Then it was given to people with ordinary obesity and did almost nothing, because their leptin was already high and the brain had stopped responding.

Mechanism: A recombinant analogue of human leptin, differing by an added methionine residue. Leptin is secreted by adipocytes in proportion to fat mass and acts at the leptin receptor on hypothalamic arcuate nucleus neurons, suppressing the orexigenic neuropeptide Y and agouti-related peptide neurons and stimulating the anorexigenic pro-opiomelanocortin neurons.

Regulatory history: FDA-approved as Myalept for complications of leptin deficiency in generalised lipodystrophy. Carries a boxed warning for anti-metreleptin antibodies with neutralising activity and for T-cell lymphoma risk, and is subject to a restricted distribution programme. Not approved for obesity or partial lipodystrophy.

Licenses medicines for the UK market. A compound without a marketing authorisation is an unlicensed medicine, which can only lawfully be supplied for human use through a prescriber under the specials scheme, not sold as a research product.

The classification above is the The Longevity Archive reading of Medicines and Healthcare products Regulatory Agency listings for Metreleptin at the reviewed date, not a legal opinion. Rules change, and importing, prescribing and possessing a compound can each be treated differently. Check the regulator directly before acting on anything here.