What Retatrutide is
Retatrutide acts at three receptors: GIP, GLP-1 and glucagon. That third arm is what separates it from tirzepatide, which is a dual GIP and GLP-1 agonist, and from semaglutide, which acts at GLP-1 alone. It is the most recent of the three and carries the least published data.
How the pen is supplied
Solution in a sealed 3 ml pen graduated in 300 dial units, stocked at two strengths. The product specification panel states 40 mg, but both 20 mg and 40 mg pens are held.
Pen specification
| Class | Triple agonist, GIP / GLP-1 / glucagon receptor |
| Also known as | LY3437943, Reta |
| Content | 40 mg |
| Fill volume | 3 ml |
| Dial graduation | 0.01 ml per unit |
| Total dial units | 300 |
| Per dial unit | 133 mcg |
| Cost per mg | £5.25 per mg |
Milligrams per dial unit and cost per milligram are calculated from the pen strength, its fill volume and the current live price. Every SerenQ pen is graduated at 0.01 ml per unit.
Verification
Independent HPLC per batch, identifier printed on the pen.
- SerenQ Retatrutide Penin stock£210
Availability checked 2026-09-04. The product page carries live stock.
Common questions
How does retatrutide differ from tirzepatide?
Receptor coverage. Tirzepatide is a dual GIP and GLP-1 agonist. Retatrutide adds a third arm at the glucagon receptor.
Which strengths are stocked?
Both 20 mg and 40 mg pens are held, though the specification panel on the product page states 40 mg only.