Limitless / Alan Glynn.

Enhanced descriptions from Syndetics:

Now a major motion picture starring Bradley Cooper, Robert DeNiro, and Abbie Cornish.

Alan Glynn's Limitless is a high-concept thriller for this Adderall age, and a haunting meditation on the allure and the curse of human potential.

A burnout at thirty-five, months behind on his book, low on cash, and something of a loser, Eddie Spinola could use a shot in the arm. One day he randomly runs into Vernon, his ex-wife's brother, and his ex-dealer. Now employed by a shadowy pharmaceutical company, Vernon has something that might help: a new designer drug that stimulates brain function. One pill and Eddie is hooked. His book is finished within days; he learns and synthesizes information at a frightening rate; and he can go a long time without sleep or food. Naturally, he begins to play the stock market. But when Vernon turns up dead, Eddie makes off with the only stash of the drug in existence. Then come the side effects: black-outs, blinding headaches, and violent outbursts he can't seem to remember.