Connecticut has joined 34 other states and the District of Columbia in filing a federal lawsuit against the two manufacturers of Suboxone, a drug that treats opioid addiction, accusing the companies of illegally blocking generic competitors from the marketplace.

The suit was filed last week against Reckitt Benckiser Pharmaceuticals Inc., which is based in the United Kingdom and does business under the name Indivior PLC, and New Jersey-based MonoSol RX.

Both companies deny wrongdoing.

The states allege that the companies are breaking state and federal laws, illegally preventing generic versions of Suboxone from being produced and sold.

Suboxone is a brand-name prescription medication that treats heroin and other opioid addictions by easing addiction cravings. At a time when opioid-related addiction, overdoses, and deaths are on the rise in Connecticut and nationally, there is no generic form of Suboxone.

According to the states, Reckitt launched Suboxone in a tablet form in 2002 and had a statutorily imposed exclusivity protection for seven years, meaning no generic version could go on the market until at least 2009. The states are claiming that, before that period ended, Reckitt worked with MonoSol to develop a dissolvable film version of the drug.

The lawsuit alleges that Reckitt then shifted marketplace demand from the tablet to the film version, through marketing, price changes, and other means, and that Reckitt later took the tablet off the market in the United States after most Suboxone prescriptions were being written for the film.

That’s illegal “product hopping,” according to the lawsuit. The states say it’s illegal for a company to make small changes to a product in order to extend its patent protections and prevent other companies from making less-expensive generic forms of the medication.

The lawsuit says the film version of Suboxone had no clear benefit over the tablet, and Reckitt still sold the tablets in other countries even after it stopped in the United States. The states also accuse Reckitt of voicing “unfounded” safety concerns about the tablet form.

As a result, the lawsuit claims, state and federal programs — including Medicaid — and consumers have been paying “artificially high monopoly prices” for the drug since late 2009, when generics may have otherwise become available.

“One of my highest priorities is determining if the dramatic increases in pharmaceutical prices over the last several years, for both brand and generic drugs, reflect violations of laws within my authority to enforce,” Attorney General George Jepsen said in a statement.

“In this case, we have a brand-name pharmaceutical manufacturer that sought to protect its profits by preventing lower-priced generic alternatives from entering the prescription drug market,” he said. “The circumstances alleged in this case are particularly egregious in that, in the midst of an epidemic of opioid abuse and addiction, Connecticut consumers and taxpayers have had to pay more for a drug that may help to mitigate some of the problem.”

The lawsuit was filed in U.S. District Court in Pennsylvania and accuses the companies of violating the federal Sherman Act, the Connecticut Antitrust Act, the Connecticut Unfair Trade Practices Act, and other state laws.

The states want the court to order “appropriate relief” for consumers and states, and to restore competition.

Indivior officials, in a company statement, said last week they are aware of the lawsuit and “the company intends to continue to vigorously defend its position.”

MonoSol CEO Keith Kendall said, in a statement: “We believe that the allegations in the complaint are wholly without merit and the suit is both factually and legally deficient. As a small, innovative company with (research and development) in New Jersey and manufacturing in Indiana, we are proud of our patented technology and the value it has brought to patients and caregivers.”

Kendall continued, “I think it is important to add that Suboxone sublingual film is a product which has saved countless lives since its approval by the FDA in 2010.”