OxyContin has been praised and blamed for many things, ranging from helping people to endure pain to exacerbating the country's opioid addiction problem. But it's coming under scrutiny for yet another allegation: misleading marketing.

The drug's claim to fame was its 12-hour window of pain relief, a benefit that helped the medication rack up sales of more than $35 billion since its introduction in the 1990s by Purdue Pharma. The drug's success propelled the family behind Purdue into the Forbes 2015 list of America's Richest Families, with the magazine pegging their net worth "at a conservative $14 billion."

While the drug undoubtedly has helped many people struggling with pain, it's also become a lightening rod in the country's fight against opioid abuse, with the medication tied to instances of overdoses and addiction. But one problem with the medication may have both increased the likelihood of addiction while padding Purdue's bottom line, according to a new investigation by The Los Angeles Times. The company marketed the drug as relieving pain for 12 hours, even though the report alleges that Purdue's internal documents reveal the company was aware the drug wore off before that in many patients.

When the drug's effects wear off before 12 hours, patients face "the beginning stages of acute withdrawal," Washington University School of Medicine in St. Louis researcher Theodore J. Cicero told the publication. "That becomes a very powerful motivator for people to take more drugs."

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OxyContin was developed as a pain treatment that would last longer than other drugs on the market, such as Percocet, and it became popular largely on the basis of its promise to deliver long-duration pain relief. But early on there were signs that the drug didn't deliver the same benefits for everyone, such as clinical trials conducted by Purdue that found many patients asked for more OxyContin before the 12-hour window was up.

In an FDA analysis cited by The Times, one-third of 164 cancer patients taking OxyContin dropped out because the medication was "ineffective." Once it hit the market, patients also questioned whether the drug really lasted for 12 hours, with messages posted with subjects such as, "Is it just me, or does oxycontin not even last 8 hours?"

Even though some doctors recommended dosing every 8 hours, Purdue continued to market the drug as a 12-hour medication, the report notes. Why? Partly to grow the drug's sales, given that 12-hour duration provided a marketing edge over rival drugs with shorter durations, the report alleges.

In an email to CBS MoneyWatch, Purdue Pharma said it "rejects the claims made by The Los Angeles Times."

"In an attempt to resurrect a long-discredited theory, the paper ignores the clinical and regulatory data that directly contradicts their story," the company said. "Over the course of two years, Purdue Pharma provided the LAT with more than a dozen hours of briefings and discussions regarding the clinical evidence supporting OxyContin's 12-hour dosing and the regulatory requirement that we promote the product as such."

It added, "Unfortunately, the paper disregarded this information, instead publishing a story that's long on anecdote and short on facts."

Questions about OxyContin's duration have been raised before, including among lawsuits a decade ago, although the cases never reached a jury, The Times noted. In December, Purdue settled a lawsuit from the state of Kentucky, which charged the company misled the public about the addictiveness of the drug.

Because some insurance companies were refusing to cover prescriptions for more than 2 pills a day, Purdue was incentivized to market the drug as a 12-hour product, The Times alleged. Rather than lose sales, the company reportedly told its sales reps to recommend increasing the dose.

"$$$$$$$$$$$$$ It's Bonus Time in the Neighborhood!" one manager wrote in a 1996 memo that told reps that raising doses was a way to win bigger bonuses, according to the report. Referring to the biggest dose available then, the manager wrote, "He who sells 40mg will win the battle."

Larger doses, though, doesn't mean the medication will last longer, and it also raises the risk of overdose.

In the meantime, OxyContin remains popular, with 5.4 million prescriptions written in 2014. More than half of the patients taking the drug for more than three months in 2014 were given doses of at least 60 milligrams, which the Centers for Disease Control and Prevention said doctors should "avoid" or "carefully justify."

Purdue said that the report "risks creating more confusion around our national opioid epidemic."

It added, "For more than a decade, Purdue Pharma has sought to play a constructive role in the fight against opioid abuse, including by reformulating OxyContin with abuse-deterrent properties and leading our industry in this area of innovation."