Retatrutide UK: research vials and the sealed pen, in UK stock

Retatrutide in the UK, in one paragraph

Retatrutide (LY3437943) is Eli Lilly's investigational triple agonist of the GLP-1, GIP and glucagon receptors. It is not a licensed medicine in the UK or anywhere else, so it cannot be prescribed; in the UK it is supplied only as a research reagent for laboratory use. ALTA PEPTIDES holds it in UK stock as a lyophilised 40 mg vial at £139.99 and as the sealed Synedica Retatrutide Pen at £159.99. Both are from manufacturer lot 07022601, and orders placed before 1pm Monday to Friday ship the same day.

What is in stock and what it costs

The vial is the cheapest way to buy the compound from us, at £3.50 per milligram. Smaller sizes cost more per milligram at every UK vendor, which is why we hold the 40 mg size. The pen costs more per milligram because the price includes a manufacturer-filled device and needles. For a vendor-by-vendor comparison of what a vial costs in the UK right now, see our retatrutide price comparison, which we update monthly.

How it is tested

Every vial carries a lot number that matches a published certificate on our certificates page. For retatrutide, the manufacturer's certificate for lot 07022601 (99.2% by HPLC) is published and a sealed pen from the same lot was tested independently by Janoshik Analytical at 99.752% purity. Our guide to reading a certificate explains what each figure means and what to check on any supplier's paperwork.

Delivery from UK stock

Orders placed before 1pm Monday to Friday leave the same day by Royal Mail Tracked 48, free over £75 (£4.95 below that). Because the stock is already in the UK there is no customs hold and no multi-week wait. Vials go out in plain, insulated packaging. We also ship to Europe for £14.95, free over £150. Details are on the shipping page.

Is retatrutide legal to buy in the UK?

As a research reagent for laboratory use, yes: retatrutide is not a controlled drug. It is not authorised by the MHRA as a medicine, and supplying it for human use would be unlawful under the Human Medicines Regulations 2012, so every reputable UK supplier sells it for research only, as we do under our research use policy. Lilly plans to apply to the US regulator in early 2027; a UK licence would come later. Our article on retatrutide in the UK covers the legal position and release timeline in full.

Learn more before you buy

New to the compound? Start with what retatrutide is, then the trial comparison in retatrutide vs tirzepatide and the format choice in retatrutide pen vs vial. Weighing up pens? Our retatrutide pen UK page explains sealed versus vendor-filled pens. The vial is reconstituted with bacteriostatic water; the peptide calculator does the concentration arithmetic.