4 x 15mg 45 IU Norditropiin FlexPro Pen by Novo Nordisk The price per IU is the same as the 10mg pen. The 15mg 45 IU NordiLet pen from Norditropin is the biggest Norditropin pen available from Novo Nordisk. Norditropin is made by Novo Nordisk and is a FDA approved Human Growth Hormone. Like all other FDA approved human growth hormone (HGH), Norditropin is a 191 amino acid chain. The nice thing about Norditropin is the FlexPro Pen comes in a pre-mixed pen that has a mg window on it. There is no mixing HGH with bacteriostatic water. The FlexPro pen comes with disposable needle caps, you do not need to mix or buy diabetic needles. The pen is by far my favorite and while other companies offer FDA approved pens, Pfizers Genotropin, Merck Serono 8mg pen, and Omnitrope's 10mg pen, the price of Norditropin is much better with the same FDA quality.