The former hedge funder who bought the rights to a lifesaving anti-toxoplasmosis drug, then jacked the price up 5,500 percent has executed this money-making maneuver before with a medicine for adults and children with kidney disease.

Jeremy Stahl at Slate.com wrote on Tuesday that when Martin Shkreli was the CEO of Retrophin — a pharmaceutical firm that is now suing him for $65 million — he bought the rights to a “decades-old” kidney medication in 2014 and raised the price to more than 20 times its original cost.

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Retrophin bought the rights to the medication Thiola — which was approved by the FDA in 1988 — and raised the cost from $1 per pill to $30 per pill.

Thiola is used in treatment of the chronic disease cystinuria, a condition that causes patients to constantly form and excrete kidney stones. Patients are typically diagnosed at a young age. Their urine contains high amounts of the amino acid cystine, which crystalizes in the kidneys and travels — often agonizingly — through the bladder and ureter.

There are around 20,000 patients currently in the U.S., many of whom are children. There is no known cure for cystinuria, but Thiola is used along with diet and other life modifications to prevent the kidney stones from forming.

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When Retrophin bought Thiola, the annual cost for patients zoomed from $54,750 to $109,500. Steve Brozak wrote in Forbes that Shkreli and his company are “turning patients into commodities like barrels of oil.”

Stahl wrote that “University of Pittsburgh School of Medicine Associate Professor of Urology Benjamin Davies called it a case of ‘predatory capitalism on the backs of the sick and silent.’ Writing for Science Transnational Medicine, pharmaceutical columnist Derek Lowe said the Thiola increase was the ‘most unconscionable drug price hike I have yet seen.’”

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Shkreli typically responds to criticism of his predatory business practices with rap lyrics by artists like Eminem or the Wu-Tang Clan.

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The 32-year-old CEO of Turing Pharmaceuticals came to national attention this week when it was revealed that he’d bought the rights to Daraprim and jacked up the price from $13.50 per tablet to $750.

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Daraprim is used to manage toxoplasmosis, a parasitic blood infection that is harmless to most people but lethal to people who are immune-compromised, including adults and children with HIV and AIDS.