Turing Pharmaceuticals CEO Martin Shkreli has defended his company’s decision to raise the price of 62-year-old medication used by AIDS patients, Daraprim, by over 5,000%.

The company acquired the rights to Daraprim in August.

Martin Shkreli has said that Turing will use the money it makes from sales to research new treatments.

Daraprim is used treat toxoplasmosis, a parasitic affliction that affects people with compromised immune systems.

After Turing’s acquisition, a dose of Daraprim in the US increased from $13.50 to $750.

The pill costs about $1 to produce, but Martin Shkreli, a former hedge fund manager, said that does not include other costs like marketing and distribution.

“We needed to turn a profit on this drug,” Martin Shkreli told Bloomberg TV.

“The companies before us were just giving it away almost.”

On Twitter, Martin Shkreli mocked several users who questioned the company’s decision, calling one reporter “a moron”.

The Infectious Diseases Society of America, the HIV Medicine Association and other health care providers wrote an open letter to Turning, urging the company to reconsider.

“This cost is unjustifiable for the medically vulnerable patient population in need of this medication and unsustainable for the health care system,” the groups wrote.

Dr. Wendy Armstrong of HIV Medicine Association also disputed the need to develop new treatments for toxoplasmosis.

“This is not an infection where we have been looking for more effective drugs,” she told Infectious Disease News.

On Wall Street, Turing shares fell sharply on September 21 after Democratic presidential candidate Hillary Clinton pledged to take action against firms hiking prices for specialty drugs.

“Price gouging like this in the specialty drug market is outrageous,” Hillary Clinton said, citing Daraprim.