Lysergic acid diethylamide (LSD, Acid, Mind detergent, Owsley, Sacrament, Ticket, Twenty-Five, LSD-25, Windowpane, etc.) is a good example. LSD does not have to be ingested to be fully effective. Placing a drop of liquid on the eye, in the ear, or on your fingertip will still allow the chemical to absorb into your bloodstream and make its way to your brain. The dosage vector is largely irrelevant.