This is not the first time the 32-year-old Mr. Shkreli, who has a reputation for both brilliance and brashness, has been the center of controversy. He started MSMB Capital, a hedge fund company, in his 20s and drew attention for urging the Food and Drug Administration not to approve certain drugs made by companies whose stock he was shorting.
In 2011, Mr. Shkreli started Retrophin, which also acquired old neglected drugs and sharply raised their prices. Retrophin's board fired Mr. Shkreli a year ago. Last month, it filed a complaint in Federal District Court in Manhattan, accusing him of using Retrophin as a personal piggy bank to pay back angry investors in his hedge fund.
Mr. Shkreli has denied the accusations. He has filed for arbitration against his old company, which he says owes him at least $25 million in severance. "They are sort of concocting this wild and crazy and unlikely story to swindle me out of the money," he said.
Daraprim, which is also used to treat malaria, was approved by the F.D.A. in 1953 and has long been made by GlaxoSmithKline. Glaxo sold United States marketing rights to CorePharma in 2010. Last year, Impax Laboratories agreed to buy Core and affiliated companies for $700 million. In August, Impax sold Daraprim to Turing for $55 million, a deal announced the same day Turing said it had raised $90 million from Mr. Shkreli and other investors in its first round of financing.
Daraprim cost only about $1 a tablet several years ago, but the drug's price rose sharply after CorePharma acquired it. According to IMS Health, which tracks prescriptions, sales of the drug jumped to $6.3 million in 2011 from $667,000 in 2010, even as prescriptions held steady at about 12,700. In 2014, after further price increases, sales were $9.9 million, as the number of prescriptions shrank to 8,821. The figures do not include inpatient use in hospitals.
Turing's price increase could bring sales to tens or even hundreds of millions of dollars a year if use remains constant. Medicaid and certain hospitals will be able to get the drug inexpensively under federal rules for discounts and rebates. But private insurers, Medicare and hospitalized patients would have to pay an amount closer to the list price.
Some doctors questioned Turing's claim that there was a need for better drugs, saying the side effects, while potentially serious, could be managed.
"I certainly don't think this is one of those diseases where we have been clamoring for better therapies," said Dr. Wendy Armstrong, professor of infectious diseases at Emory University in Atlanta.
With the price now high, other companies could conceivably make generic copies, since patents have long expired. One factor that could discourage that option is that Daraprim's distribution is now tightly controlled, making it harder for generic companies to get the samples they need for the required testing.
The switch from drugstores to controlled distribution was made in June by Impax, not by Turing. Still, controlled distribution was a strategy Mr. Shkreli talked about at his previous company as a way to thwart generics.
Some hospitals say they now have trouble getting the drug. "We've not had access to the drug for a few months," said Dr. Armstrong, who also works at Grady Memorial Hospital, a huge public treatment center in Atlanta that serves many low-income patients.