SciCurious has written an interesting post about Sigmund Freud's experiments with cocaine.
Freud, the father of psychoanalysis, was also a pioneer of psychopharmacology; as well as being one of the first to scientifically investigate the properties and effects of cocaine, he also played a key role in the growth of the pharmaceuticals industry.
In 1884, Freud read a paper which described the effects of cocaine on Bavarian soldiers. The author, a German physician named Theodor Aschenbrandt, reported that the drug suppressed the appetite and increased mental powers and endurance.
Intrigued, Freud obtained some samples of the drug, and began to experiment with it himself. Later that year, he published a review called Uber Coca ("About Cocaine"). This was Freud's first paper; it contains the "definitive description of the effects" of the drug on humans:
exhilaration and lasting euphoria, which in no way differs from the normal euphoria of the healthy person...You perceive an increase of self-control and possess more vitality and capacity for work...In other words, you are simply normal, and it is soon hard to believe you are under the influence of any drug....Long intensive physical work is performed without any fatigue...This result is enjoyed without any of the unpleasant after-effects that follow exhilaration brought about by alcohol...Absolutely no craving for the further use of cocaine appears after the first, or even after repeated taking of the drug...
Freud became extremely enthusiastic about the drug - "I take very small doses of it regularly," he said, "against depression and indigestion" - and regarded it is as something like a panacea, which would be an effective treatment for various conditions, including asthma and addiction to morphine and alcohol.
The pharmaceuticals companies Merck and Parke Davies, which had only just been established, began paying him to promote and endorse their rival brands of the drug. At around the same time, Karl Koller, an ophthalmic surgeon, discovered that cocaine was an excellent local anaesthetic.