From Battlestar Wiki, the free, open content Battlestar Galactica encyclopedia and episode guide
Serisone is a medical drug applied via injector. It is included with all medkits.
It can prevent fluid buildup in lungs, if administered regularly. Socinus receives doses of the drug after suffering injuries from a Raptor crash on Kobol (TRS: "Scattered").
This drug is most likely named to resemble similar real anti-inflammatory corticosteroids like Prednisone. Based on the description of its action, Serisone is most likely similar to Lasix (furosemide), a high ceiling loop diuretic used to draw fluid from the lungs.