check your units bro - 10mg absorption is a lot, especially when the numbers like 1800 are in nanograms. (well nanograms/deciliter.)
"On the average, an adult human male who weighs 70 kg. has a blood volume of about 5 liters, or a little more than 5 quarts."
http://hypertextbook.com/facts/1998/LanNaLee.shtml
5 liter = 50 deciliter
http://www.onlineconversion.com/volume.htm
10 milligram = 10,000,000 nanogram
10,000,000ng/50dl = 200,000ng/dl - of course absorption would not be even close to 100% in this case and I am not clear on the mechanisms involved but by crunching the numbers a value of 1800ng/dl seems doable.