Nicotine is active IV. Dunno that there would be much point to it?
"...The first modern scientific evidence for this conclusion appeared in the English medical journal Lancet in 1942. Dr. Lennox Johnston there reported that he had given small injections of nicotine solution to 35 volunteers, including himself. "Smokers almost invariably thought the sensation pleasant," Dr. Johnston declared, "and, given an adequate dose, were disinclined to smoke for a time thereafter.... After a course of 80 injections of nicotine, an injection was preferred to a cigarette." If the nicotine injections were abruptly discontinued, craving arose. Dr. Johnston found that in satisfying this craving, one milligram of injected nicotine was roughly the equivalent of smoking one cigarette. He concluded that "smoking tobacco is essentially a means of administering nicotine, just as smoking opium is a means of administering morphine."
Lennox M. Johnston, "Tobacco Smoking and Nicotine," Lancet, 243 (December 19, 1942): 742.