I thought the purpose of igf1-Des was to get site enhancement by keeping the Des localized within the muscle trained? Why would you want it to go systemic?
Des is such a tiny molecule, which for the most part is the reason it is 10x more anabolic then regular igf1, because it can more easily fit into the igf1 receptor. I would want the Des to stay localized in an attempt to control where it does its magic.
Intravenous administration of any compound gets it in your system fastest causing a high spike of the drug in the body with 100% absorption. I have heard of pros doing this with pharmaceutical grade HGH immediately post workout.
It's not smart to do so with generic HGH or peptides. The powder you see in peptides is not the peptide itself. That's the fillers they add for visual presentation in order to make the customer think there is actually something in the vial. The research companies I've repped for at times had peptides synthesized and bottled without added fillers for a more pure product, but there were too many complaints by those who thought since they couldn't visually see the peptide that they got an empty vial or an inferior product, which is quite contrary to the truth. 1mg is 1/1000 of a gram. It's barely visible to the naked eye.
Back to the OP and his original question on intravenous administration of Des. I have iv'd generic HGH, and GH peptides, just to see what would happen. I felt it hit harder and faster, but I really don't see any advantage to doing this for bodybuilding purposes. I merely did it as an experiment.