UPDATE 1-Allergan sues Pfizer over costs of opioid litigation

(Adds comment from Pfizer)

Aug 2 (Reuters) - Allergan Plc on Thursday sued Pfizer Inc to require its rival to cover any damages it is forced to pay as a result of hundreds of lawsuits claiming Allergan deceptively marketed an opioid it acquired from a company Pfizer bought.

In a lawsuit filed in federal court in Cleveland, Ohio, Allergan said the "primary basis" for the claims against it was the alleged improper marketing and sale of Kadian, a form of morphine, in the years before it gained rights to the painkiller in late 2008.

"But now that more than a thousand lawsuits seek to impose liability for that very marketing and sale, Pfizer has rejected any responsibility to indemnify Allergan," alleged Allergan Finance LLC, the subsidiary that filed the lawsuit.

Pfizer in a statement said Allergan's claims related to a drug it never sold and arise from a contract with King Pharmaceuticals Inc, which Pfizer acquired in 2010.

"We will review Allergan's suit and respond accordingly," Pfizer said.

Opioids were involved in more than 42,000 overdose deaths in 2016, according to the U.S. Centers for Disease Control and Prevention.

Drugmakers including Allergan, Purdue Pharma LP and Endo International Plc are facing a wave of lawsuits by state and local governments accusing them of pushing addictive painkillers through deceptive marketing.

At least 1,021 lawsuits are consolidated before U.S. District Judge Dan Polster in Cleveland. The first trial is set for March.

Plaintiffs' lawyers pursuing the cases have compared them to the litigation by states against the tobacco industry that led to a $246 billion settlement in 1998.

In its complaint, Allergan said most of the lawsuits it faces seeking to hold it responsible for playing a role in the opioid crisis primarily relate to improper marketing of Kadian and involve allegations dating back to the mid-1990s.

The drug at that time was owned by Alpharma Inc, which King Pharmaceuticals acquired in 2008, the same year King sold the rights to Kadian to Actavis. In 2016, Actavis acquired Allergan and took on the company's name.

Sale of rights to Kadian was a condition of winning U.S. antitrust approval for King's acquisition of Alpharma.

Allergan argued that Pfizer under the terms of an agreement Actavis signed with King in 2008 was required to indemnify it for any damages arising out of the pre-2009 marketing of Kadian.

But Allergan said Pfizer has rejected its claim for indemnification.

The case is In re National Prescription Opiate Litigation, U.S. District Court, Northern District of Ohio, No. 17-md-2804. (Reporting by Nate Raymond in Boston Editing by Bill Berkrot and Matthew Lewis)