BETWEEN 1999 and 2014 sales of prescription opioid drugs almost quadrupled in America, an increase that came not simply in response to patient suffering but because more of the population are addicted to these powerful drugs. Such is the demand for them, Americans now consume four-fifths of the global supply.

Growth on this scale has been profitable for some: OxyContin, a popular opioid made by Purdue Pharma, a drug company in Stamford, Connecticut, has made its manufacturer tens of billions of dollars (see chart). But more broadly it has spelled tragedy. Deaths from opioid use in America quadrupled over the same period. About 90 people die every day, according to the Centres for Disease Control and Prevention.

That dissonance between corporate success and private pain has become a matter of public interest. On March 28th Senator Claire McCaskill, a Democrat from Missouri, said that she would investigate the role that pharma firms played in creating the opioid crisis. Through a committee that oversees issues of homeland security and government affairs, she has written to five makers of prescription painkillers—Purdue Pharma, Depomed, Janssen/Johnson & Johnson, Insys Therapeutics and Mylan. She is demanding internal corporate documents stretching back over five years. Ms McCaskill wants to know exactly how firms marketed their drugs and what they knew about the risks of addiction and abuse. In particular, she wants to find out if companies used calculated sales-and-marketing strategies that involved encouraging doctors to prescribe opioids for a wider category of causes of pain than they would otherwise have done and downplaying the risk of addiction. This is not the first time such questions have been raised. In a case in 2007, the parent company of Purdue Pharma and three current and former executives there pleaded guilty to criminal charges that they misled regulators, doctors and patients about OxyContin’s risk of addiction and potential for abuse. Purdue promoted the drug, which is long-acting, as posing a lower risk of abuse and addiction than shorter-acting painkillers—such as Percocet and Vicodin. The firm admitted it had made statements about its drug that were “inconsistent” with approved prescribing information. In other words, the firm had incorrectly told doctors that OxyContin was less prone to abuse than other opioid medicines. The firm agreed to pay $600m and the three executives paid $34.5m in fines. Ms McCaskill’s inquiry is not the only one drug firms face. The Department of Justice (DoJ) has alleged that kickbacks were offered to encourage drug prescriptions and also that, as a result, health insurers were defrauded. In December the DoJ arrested former senior staff at Insys Therapeutics on charges that they led a conspiracy to bribe doctors to unnecessarily prescribe patients a pain medication based on fentanyl (an opioid that is up to 50 times as powerful as heroin), defrauding the insurers who had to cover the drug’s cost. The Drug Enforcement Administration has also taken action against firms for failing to control the “diversion” of prescription drugs to illicit uses. Earlier this year McKesson, a San Francisco-based pharma distributor, agreed to pay $150m for failing to report suspiciously large orders of drugs.

Increasingly, too, counties and cities are filing lawsuits against manufacturers for their role in the opioid epidemic. There may be further legal action against the firms that distribute opioid medicines, acting as intermediaries between pharma firms and pharmacies. Some have been named in lawsuits.

Nora Volkow, director of the National Institute on Drug Abuse, says that pharma companies are not the only ones to blame for the opioid crisis. She points to well-meaning efforts to implement procedures to make sure that pain was not under-treated in hospitals. Direct-to-consumer advertising of opioids may also have encouraged overuse. Only America and New Zealand allow pharma firms to advertise drugs directly to patients.

The scrutiny on the industry is nonetheless intensifying. The number of opioid prescriptions being given is no longer rising, and may be falling. The same cannot be said for drugs firms’ legal woes.