Harris County filed suit against three insulin manufacturers this week, accusing the firms of colluding to set artificially high prices for the medicine and other diabetic treatments.

The suit estimates the alleged 15-year scheme costs the county millions of dollars annually through higher health care costs for employees, their dependents and inmates in the Harris County Jail.

“We are bringing this lawsuit to hold these billion-dollar companies responsible for conspiring to drive up the prices of their life-saving insulin for our residents, while securing record profits for themselves,” County Attorney Vince Ryan said Thursday.

The county names as defendants the three largest manufacturers of insulin — Eli Lilly, Novo Nordisk and Sanofi — as well as the four largest pharmaceutical benefit managers: Aetna Rx, CVS Caremark, Express Scripts and Optum Rx.

“We are aware of the complaint and disagree with the allegations made against the company,” Novo Nordisk said in a statement. “We will vigorously defend ourselves in this matter.”

Sanofi declined to comment; Eli Lilly did not respond to a request for comment.

Harris County is accusing the companies of fraud, civil conspiracy and violation of Texas’ antitrust statute. In the lawsuit, which was filed in state district court, Ryan called insulin “the poster child for pharmaceutical price gouging.”

Ryan accused the manufacturers of raising prices to curry favor with the benefits providers, who in turn will generate more lucrative profits from selling the drugs.

Insulin that sold for $20 per vial in the late 1990s now retails for $300 to $700, Ryan said. As a result, Ryan said Harris County now spends more treating diabetes than on medications related to any other disease. From 2014 to 2015, he said the amount the county spent on diabetes spiked by more than 60 percent.

The county provides health insurance to about 38,000 employees and their dependents, as well as about 9,000 inmates daily at the Harris County Jail.

Dr. Sherri Onyiego, a family physician at Harris County Public Health, said affordable insulin is crucial for diabetes patients.

“If a person can’t afford their insulin, it adds to their likelihood of having complications,” Onyiego said.

Harris Health, the county public health provider that had 1.7 million clinic visits in 2018, is a separate legal entity and is not included in the suit, Assistant County Attorney Pegi Block said.

Harris County is seeking to recoup at least $27 million. Ryan noted the original discoverers of insulin sold patents for the drug for $1 in 1923, in the hope it would remain affordable for patients.

The manufacturers singled out by Ryan face similar lawsuits elsewhere. A group of diabetes patients filed a class action in 2017, alleging Eli Lilly, Novo Nordisk and Sanofi accuses the insulin makers of conspiring to collectively raise prices for the drug. A New Jersey judge in February allowed the case to proceed. It now includes more than 100 plaintiffs in several dozen states.

In the past two years, the attorneys general of Minnesota and Kentucky have 2018 sued the same trio of drug makers. A spokeswoman for Texas Attorney General Ken Paxton said the office would not comment on pending litigation.

Ryan in 2017 joined dozens of cities and counties in suing pharmaceutical companies who manufacture opioids. Harris County accused 21 companies, several doctors and one pharmacist of conspiracy, neglect and creating a public nuisance in a case modeled after the class action Big Tobacco lawsuits filed by states in the 1990s.

Last week, Ryan decided to break with other local governments negotiating a joint settlement so Harris County could pursue its own settlement. Ryan said he did not want to be bound by a settlement forged by other cities and counties, and said he believed Harris County could secure a more lucrative settlement itself.

zach.despart@chron.com