LITTLE ROCK — Attorney General Leslie Rutledge joined Friday with attorneys general from 34 other states and the District of Columbia in filing an antitrust lawsuit against the makers of a drug used to treat opioid addiction.

The suit alleges that Reckitt Benckiser Pharmaceuticals, now known as Indivior, conspired with MonoSol Rx to switch the drug Suboxone from a tablet version to a film, similar to a breath strip, in order to delay generic alternatives and maintain monopoly profits. The companies are accused of violating Arkansas and federal antitrust laws.

Suboxone is a brand-name prescription drug used to treat addiction to heroin and other opioids by easing addiction cravings. No generic alternative of the film is currently available.

According to the suit, when Reckitt introduced Suboxone in 2002, it had exclusivity protection that lasted for seven years. Before that period ended, however, Reckitt worked with MonoSol to create a film version of Suboxone, and the suit alleges that over time, Reckitt converted the market away from the tablet to the film through marketing, price adjustments and other methods.

After the majority of Suboxone prescriptions were written for the film, Reckitt removed the tablet from the U.S. market, according to the suit. The suit accuses Reckitt of “product hopping,” or making modest changes to a product to extend patent protections so other companies cannot enter the market and offer cheaper generic alternatives.

As a result, the suit alleges that consumers have paid artificially high prices since late 2009, when generic alternatives of Suboxone might otherwise have become available. During that time, annual sales of Suboxone topped $1 billion.

The suit, filed in the U.S. District Court for the Eastern Division of Pennsylvania, asks the court to stop the companies from engaging in anti-competitive conduct, restore competition and order appropriate relief for consumers and the states.

Indivior said on its website Friday it will “vigorously defend” its position that it did nothing wrong.

Other states involved in the suit are Alabama, Alaska, California, Colorado, Connecticut, Delaware, Florida, Hawaii, Illinois, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Nebraska, New York, North Carolina, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Carolina, Tennessee, Utah, Vermont, Virginia, Washington and Wisconsin, as well as the District of Columbia.