Retatrutide pen UK: the sealed Synedica pen, and how to tell pens apart

What a retatrutide pen is

A retatrutide pen, often called a reta pen, is the compound already in solution inside a multi-use injector device, rather than a dry powder in a vial. Our Retatrutide Pen is the Synedica pre-filled pen holding 40 mg of retatrutide, boxed with pen needles and the manufacturer's leaflet, at £159.99. Nothing needs reconstituting. It is supplied for laboratory research only.

Sealed manufacturer pen or vendor-filled pen?

This is the question that matters most when comparing pens in the UK. A sealed manufacturer pen is filled by a named manufacturer and reaches you unopened, so the concentration and the fill are the manufacturer's, and the compound can be traced to a tested lot. A vendor-filled pen is one a seller has made up from a vial and loaded into a cartridge itself, so what is in it rests on that seller's word alone, with no certificate for the solution. We only supply the sealed Synedica pen and we do not fill pens ourselves. Our pen vs vial guide compares all three formats side by side.

Certificate and independent test

The retatrutide in our pen is from manufacturer lot 07022601, the same lot as our vial, and the manufacturer's certificate for that lot (99.2% by HPLC) is published. A sealed pen from the same lot was tested independently by Janoshik Analytical at 99.752% purity. The full reports are on our certificates page.

Pen or vial: which costs less?

The 40 mg vial is cheaper per milligram (£3.50 per mg) than the pen (£159.99 for 40 mg) because the pen price includes the device, the manufacturer's preparation and the needles. Our retatrutide price comparison sets both against other UK sellers.

Storage and delivery

Keep the pen refrigerated at 2 to 8 °C, protected from light and capped, within the manufacturer's stated in-use period; do not freeze it. It ships from UK stock in insulated packaging, the same day on orders placed before 1pm Monday to Friday, by Royal Mail Tracked 48, free over £75.

The legal position

Retatrutide is not a licensed medicine in the UK and has no marketing authorisation anywhere. The pen is sold strictly as a laboratory reagent under our research use policy; nothing on this page is guidance on using it. For the compound itself and its trial results, see what is retatrutide. For vials and delivery, see retatrutide UK.