Lawmakers and AIDS specialists are protesting the “overnight” increase of a drug that helps to battle parasitic infections in the elderly, infants, and AIDS patients.

The rights to the 62-year-old drug, called Daraprim, was purchased in August by Turing Pharmaceuticals, a small start-up company founded by Martin Shkreli.

Shkreli raised the price of Daraprim from $13.50 a pill to $750 a pill. The 5,000% price increase drew sharp criticism from lawmakers as well as infectious disease specialists.

Shkreli defended his price hike as a good “business strategy” to raise instant profits while saving lives. He said the price of Daraprim is affordable compared to other drugs used to treat parasitic infections.

“This isn’t the greedy drug company trying to gouge patients, it is us trying to stay in business,” he told the NY Times. “This is still one of the smallest pharmaceutical products in the world,” he said. “It really doesn’t make sense to get any criticism for this.”

Shkreli also raised eyebrows when he purchased a hedge fund company in his 20s, and urged the Food and Drug Administration not to approve certain life-saving drugs made by companies whose stock he was short selling.

Short sellers make their money by using margin accounts to borrow stock that they don’t own. They then wait for the stock price to drop so they can sell the stock at a profit. (Randolph Duke suffered a heart attack when he heard the words “margin call, gentlemen,” in the movie Trading Places.)