Second, the Pegasys is BIG
and slowly absorbed from the injection site
and carried to the liver where it acts on liver cells. Its level in the blood rises and stays high for 4-7 days.
On the other hand, PegIntron is a smaller more fragile molecule and is fairly rapidly metabolized and excreted. Its level in the blood rises during the first 2-3 days after injection and quickly falls so that by day 5 - day 7 you may have NO drug in yr body.