It is ill-advised to intravenously inject pharmaceuticals that are prepped for oral consumption. There are methods of extracting the amphetamine from the binders/fillers that make up the capsule.
I have been taking Adderall for a few years now. Try crushing some of the 'beads' inside the capsule and insufflating.
Otherwise you can empty some of the beads into your mouth and chew the beads before swallowing them. This can enhance the onset.