Martin Shkreli, the former CEO of Turing Pharmaceuticals, appearing before a hearing in Washington. Thomson Reuters

Medicare spent over $500 million on a drug called Acthar in 2015.

The drug, which was approved by the Food and Drug Administration before it implemented current standards, is the only one in the top 20 for Medicare that isn't considered life-saving.

Now investors are suing Mallinckrodt Pharmaceuticals over the company saying Acthar's success is not dependent on government money.

Now, don't get me wrong — we're no fans of Martin Shkreli.

But we owe him credit for doing something right. In 2014, he complained to the feds — specifically the Federal Trade Commission — about a drug company's anticompetitive behavior.

That company is called Mallinckrodt Pharmaceuticals, or MNK, and it was recently forced to pay a $100 million fine for squashing competition of its blockbuster drug, Acthar.

This merits discussion because MNK's problems didn't end with that payment.

MNK recently disclosed that it has joined the ranks of other big drug companies like Gilead, Valeant, and Celgene being investigated by Justice Department for its patient-assistance programs. The pharmaceutical industry spends about $7 billion a year on these programs.

What Washington wants to know is whether these programs actually help patients or just help companies keep drug prices high. Because of that concern, government programs like Medicare and Medicaid already don't accept the help of patient-assistance programs.

Mallinckrodt, like most of the other drugmakers, hasn't said much about what its investigation is focused on.

But by piecing together government data on the sales of Acthar and the company's own disclosures, and examining its relationship with the company that manages its patient-assistance program, it's not hard to get a sense of all the things the government should be worried about.

This drug, which isn't considered life-saving and is more than 50 years old, is one of the costliest for US government programs, costing taxpayers over a half a billion dollars in 2015.

The main problem Acthar is supposed to treat afflicts infants, but the program that is spending hundreds of millions of dollars on it is Medicare Part D, which assists elderly people. Looking at the numbers, you're left with more questions than answers.

What is certain, however, is that if this is the way the industry is doing business, you should be worried about it, too.

The players club

Before we dive in, there are a few things you should know about Acthar — or more technically, HP Acthar Gel:

Acthar is mostly used as a treatment for infantile spasms.

MNK bought Acthar, which is made from a pig's pituitary gland, in 2014. Now it's the company's top-selling drug and could account for up to 40% of the company's revenue in 2017.

Acthar is typically given for two to four weeks and generally requires two to three vials at a price of $38,200 per vial.

It's also one of the top 20 best-selling drugs for Medicare's Part D program, and it's the only drug in the top 20 that doesn't treat a life-threatening disease.

In fact, there's a debate about whether Acthar is effective at treating anything at all. It's been around since the 1950s and was approved before the Food and Drug Administration required the kind of clinical trials it does now. The drug has 19 "indications," which means it is used as a treatment for 19 ailments, including lupus, some dermatological diseases, and multiple sclerosis.

Because of that last point, MNK has become something of a flashpoint in the industry. Wall Street short-seller Andrew Left once showed up on CNBC with a $1 million check and said he would donate it to multiple sclerosis research if MNK tested Acthar.

MNK ignored him. They also ignored multiple requests for comment on this story.

Andrew Left. Bloomberg

Another important part of Acthar is its relationship with the distributor Express Scripts, which is also being investigated over its patient-assistance programs.

Express Scripts is not a drug company. It is the country's largest pharmacy benefit manager, servicing just under a quarter of health insurance plans, public or private. That means it manages the list of drugs your insurance company — or whoever is paying for your drugs — pays for. It's a gatekeeper that is supposed to keep costs down.

But that's not all Express Scripts does. It also has an internal mail-order specialty pharmacy called Accredo Health, which takes a percentage off every drug that it sells, and a business that manages patient-assistance programs, called United BioSource.

Express Scripts doesn't like to talk about its United BioSource clients. It also doesn't like to talk about which United BioSource clients also have agreements to sell through Accredo Health. We asked the company about that a few months ago, and it said that was all confidential.

What we do know, though, is that Acthar is one of the drugs that have patient-assistance programs managed by United BioSource — check out the form here — and that it is sold by Accredo Health.

We also know that Accredo is paid based on how much Acthar it can get out the door and into the hands of patients — a fact the company denied, and then confirmed, in emails with Business Insider.

Express Scripts says United BioSource gets money based on how much staff it needs to figure out who should or should not receive help from its patient-assistance program. It doesn't make the rules of those programs, and those rules are proprietary to its client — in this case, MNK, which would not answer questions about it.

Government programs don't allow these programs to pay co-pays for patients, because that makes it easier for patients to run up a massive medical tab without thinking about it. Keep that in mind.

Can I live?

Now that you know who's running and helping to sell Acthar, we can bring the government into the mix — because it's doing most of the paying.

MNK sold about $1 billion in Acthar in 2015, and about 65% of that was sold to the government through Medicare and Medicaid.

Acthar was one of the top 20 drugs bought for Medicare Part D patients in 2015, according to the program. Medicare Part D spent about $500 million on the drug for just 3,104 people.

It is also the only drug on the top-20 list that is not considered life-saving.

Of that $500 million, a little over half goes to patients who are low-income subsidized, so the government is shelling out almost the entire $38,000 price of the drug. Medicare spent an average of $162,371 on each Acthar patient in 2015. The average cost per vial was $6,827.

Digging into those numbers, if only 3,104 people are taking Acthar, that means Medicare is paying for an average of 23.7 doses per person per year.

For Medicare Part D patients who are not low-income subsidized, though, Acthar costs an average of $8,000 out of pocket a year, the Centers for Medicare and Medicaid Services says.

Sure, that's not $38,000, but it is still a pretty high price for seniors to pay. Express Scripts told us the drug's co-pay for Medicare Part D patients that it manages is $2,000.

The top 20 drugs bought by Medicare Part D in 2015. Medicare

So how are under half of them paying for Acthar if they can't use MNK's patient-assistance program?

We asked Andrew Miller of the Detroit-based pharmacy benefit manager Meridian what he thought of this Acthar conundrum. Many of his clients are on government insurance, especially Medicaid. He said that even though Acthar isn't on his formulary — the list of drugs his company will allow insurers to pay for — if a patient needs the drug, it can go through an exception process.

Thing is, adults really don't ask for it. The only times he needs to make an exception for Acthar is when it's being used to treat infantile spasms. He said he has never approved its use for anything adults would need.

"It is rare for any beneficiary, regardless of type of insurance (Medicare or commercial), to pay $8,000 out of pocket for most therapies," he told Business Insider in an email. "Usually when the out-of-pocket expense is this high, there is some sort of copay assistance or manufacturer program option."

So we asked Express Scripts about it, and it was precise with its answer.

"The Acthar Gel PAP does not pay any OOP costs for patients with pharmacy coverage," the company told us of its patience-assistance program (its emphasis).

However, it said it would give the drug away if a patient were to qualify. And Accredo is also willing to point patients in the direction of a charity that would help them take care of the co-pay.

"As a company dedicated to caring for patients with chronic and complex conditions, we support or work with a variety of charitable organizations that assist patients," the company said in an email. "We cannot advise as to whether any of the many charities we have supported offer a patient-assistance program, but we state that we do comply with regulatory requirements in making charitable donations."

So somehow, some way, these drugs are getting paid for. Or, more accurately, they're getting into people's hands.

This game has a cheat

We saw the dirty version of this game being played at another mail-order pharmacy in 2015. It was called Philidor, and the pharmacy was secretly owned by a drug company called Valeant Pharmaceuticals until October 2015. The revelation of Philidor's existence brought Valeant to its knees, and since then, its stock price has fallen from a high of $260 to $16.

And here's why: Philidor's game, according to internal documents viewed by Business Insider, was to get as much Valeant product out the door as possible, often by paying co-pays for patients. Once the patient had the drug, Philidor would keep sending refills and charging the patient's insurer.

Sometimes Philidor would get paid and sometimes it wouldn't, but the more drugs it was able to send out, the more claims it could try to get filled.

That's where the money is — in getting the drug out the door and then doing whatever possible to get the claim filled afterward.

This is why senators like Elizabeth Warren, Democrat of Massachusetts, raged about Valeant's patient-assistance programs when company executives were in the hot seat on Capitol Hill last year. Former CEO Michael Pearson said he didn't know how much money using patient-assistance programs was netting them, which left Warren incredulous.

If you listen to MNK — and even some people on Wall Street — the company doesn't rely on government sales for its blockbuster drug's survival. In fact, it will tell you that 60% of its sales are to patients with private insurers.

But the numbers don't actually show that. Ever since MNK bought Acthar in 2014, its sales to Medicare Part D especially have exploded, driving growth.

In 2013, the program spent $262.6 million on the drug. In 2014, that jumped to $391.2 million, and then in 2015, the program spent $504 million on the drug.

So investors are upset. Last month, shareholders filed a lawsuit against MNK, accusing it of lying about its reliance on Medicare and Medicaid for Acthar's revenue. The Securities and Exchange Commission is also looking into the matter.

But the question here isn't just who pays for Acthar, it's how the drug is paid for. Every taxpayer should be wondering why a drug that has never been properly tested is being sent to 3,104 Americans an average of 23 times a year at a cost of over half a billion dollars.

Nobody wants to be a bag holder.