It may be very difficult for non-IV users to understand the difference and the power and magnitude of IV administration. IF the procedure is done properly, it is realitively benign. And yes, many people can eat 7.5 miligrams orally, ive even witnessed someone consume a 100ug/hr patch (little to zero tolerance). But of course, this is no suggestion in any way, in fact i suggest starting at the lowest possible dose and slowly tritrate upwords. But, i have injected 20mg of fentanyl MORE than once, yes 20 milligrams, 20,000 micron grams. But so what, i have an unfortunately high tolerance, as its all realitive. If you are injecting those kind of doses, you are certainly not a newbie an should be quite familiar with your personal tolerance, injection techniques etc......
Becarefull, and like i said, start just above threshold doses and titrate to the deisred amount........