Here's how a pharma CEO defended his decision to make a critical drug 55X more expensive overnight

Turing Pharmaceuticals CEO Martin Shkreli has been under fire since Sunday for raising a 62-year-old drug's price from $13.50 to $750 per pill.

And he hasn't stayed quiet. 

Turing, a pharmaceutical startup that launched back in February, acquired the US marketing rights to the parasitic infection-fighting drug Daraprim in August. 

Almost immediately, Turing jacked up the price of the drug, which is used to prevent malaria and treat toxoplasmosis, a parasitic infection that's dangerous for pregnant women's unborn children and for people with weakened immune systems, such as those with AIDS and patients undergoing chemotherapy.

The price hike first drew the attention of medical associations earlier this month and was the focus of a New York Times article published earlier this week. On Twitter this Monday, Democratic presidential candidate Hillary Clinton responded to the Times article:

And on Tuesday at a speech in Des Moines, Iowa, she did just that. Additionally, she directly called out Shkreli's recent activities, saying, "It's price-gouging pure and simple."

PhRMA, the trade group that represents the pharmaceutical industry in the US, isn't sticking by Turing's side either (though a Turing spokesman recently told Bloomberg that PhRMA "should check their membership roster"): 

Yet Shkreli has remained steadfast, at least on Twitter and during several recent talk show appearances. Late on Tuesday, however, Turing announced it would potentially role back the increase.

Here are some of the arguments Shkreli made in support of his company's decision to raise the price of a life-saving medication.

"If there was a company that was selling an Aston Martin at the price of a bicycle, and we buy that company and we ask to charge Toyota prices, I don't think that that should be a crime."

Shkreli told CBS This Morning on Tuesday that the reason he drove up the price was to make the company profitable. "This drug was doing $5 million in revenue," he continued. "And I don't think you can find a drug company on this planet that can make money on $5 million in revenue. Most costs are much higher than that."

His argument is that it costs a lot to keep a drug company up and running. It's not just how much money they're spending on researching and developing new treatments - it's also operating costs, marketing expenses, access plans, education efforts, etc. The difference here is that most companies stick to raising money from investors the first few years before they bring a new drug to market.

"Half of our drug we give away for $1. So I think that shows our commitment to patients."

Shkreli argues that he'll be giving away most of his product for close to nothing. He told BloombergTV on Monday he plans to expand the free drug program and eliminate copays for people who have trouble affording the treatment. "We will never deny someone treatment for their inability to pay," he said. 

"They don't deserve a drug that's 70 years old. They deserve a modern medicine that can cure toxoplasmosis quickly."

Daraprim, which was first approved by the FDA in 1953, has been successful in curing toxoplasmosis for more than 60 years. But Shkreli told BloombergTV that it's not a perfect drug, calling it "a very toxic drug" His idea is to price Daraprim high so that his company has the resources to develop new drugs.

Still, nothing beats Shkreli's barrage of tweets in response to people who are outraged at the cost. Unfortunately, it looks like @MartinShkreli will be going private later tonight.