We needed to turn a profit on this drug," Mr Shkreli told Bloomberg TV. "The companies before us were actually giving it away almost."
He says the practice is not out of line with the rest of the industry.
"These days, modern pharmaceuticals, cancer drugs can cost $100,000 or more, whereas these drugs can cost half a million dollars. Daraprim is still underpriced relative to its peers," he told Bloomberg TV.
On Twitter, Mr Shkreli mocked several users who questioned the company's decision, calling one reporter "a moron".