Drug companies including Sanofi S.A. and Pfizer Inc. have brought in some of the nation's top defense attorneys in more than two dozen lawsuits brought over last month's recall of over-the-counter heartburn medication Zantac.

Anand Agneshwar, co-chairman of Arnold & Porter Kaye Scholer's products liability litigation practice, made an appearance Wednesday before the U.S. Judicial Panel on Multidistrict Litigation on behalf of Sanofi, which voluntarily recalled Zantac on Oct. 18 after the Federal Drug Administration discovered it contained an ingredient linked to cancer. Mark Cheffo, co-chairman of the products liability and mass torts practice at Dechert, appeared for GlaxoSmithKline, which first received FDA approval to sell Zantac in 1983. GlaxoSmithKline has a U.S. unit based in Philadelphia.

Last week, Williams & Connolly chairman Joseph Petrosinelli appeared for New York-based Pfizer, and Covington & Burling's Paul Schmidt appeared for Boehringer Ingelheim Pharmaceuticals Inc., which has U.S. headquarters in Ridgefield, Connecticut. Pfizer and Boehringer Ingelheim sold Zantac over the counter.

Plaintiffs lawyers, predicting a "real explosion" of lawsuits filed over Zantac, asked the MDL panel earlier this month to coordinate the litigation in New Jersey. Sanofi's U.S. headquarters is in Bridgewater, New Jersey.

The lawsuits, both consumer class actions and individual personal cases, allege that Sanofi and other drug companies knew that ranitidine, the active ingredient in some heartburn medications, metabolizes into unsafe levels of a possible carcinogen, known as N-Nitrosodimethylamine, or NDMA, but failed to disclose the information to their customers. The FDA earlier this month said its preliminary tests had discovered NDMA in certain ranitidine medicines, such as Zantac, but it is still investigating.

The lawsuits, the first of which was filed Sept. 13, follow the FDA's investigation of NDMA in some blood pressure and heart failure medicines. Last year, the FDA found a carcinogen in those medications, such as generic valsartan, prompting the filing of more than 140 lawsuits now coordinated in multidistrict litigation in New Jersey.

"This litigation will almost certainly dwarf the valsartan litigation because of the ubiquity of Zantac and because the NDMA in Zantac is not an impurity that only recently made its way into the drug through shoddy manufacturing but is instead inherent to the drug's molecular structure," wrote attorney Steve Berman in a Nov. 4 motion to transfer the cases. "Thus, over the more than 30 years that Zantac has been sold in the United States, every one of the millions of the drug's consumers has been exposed to dangerous levels of NDMA and many thousands of those consumers have contracted cancer as a result."

Berman, of Seattle's Hagens Berman Sobol Shapiro, sought an MDL along with James Cecchi of Carella, Byrne, Cecchi, Olstein, Brody & Agnello in Roseland, New Jersey; Bob Hilliard, of Hilliard Martinez Gonzales in Corpus Christi, Texas; and Craig Raabe of Izard Kindall & Raabe in West Hartford, Connecticut.

Other lawyers have suggested alternative venues such as the Southern District of Florida or Northern District of California.

Agneshwar, in New York, and Petrosinelli, in Washington, D.C., did not respond to requests for comment. Schmidt, who works in both New York and Washington, D.C., and Cheffo, in New York, declined to comment.

In a statement, Pfizer spokeswoman Sally Beatty wrote, "Pfizer is named in only certain actions identified in the plaintiffs' petition, and believes those complaints are without merit. The company is reviewing the plaintiffs' petition for creation of an MDL and will respond in due course."

Here's more about the defense team:

• Agneshwar, the lawyer for Sanofi: handled the California Supreme Court case that prompted Bristol-Myers Squibb to petition the U.S. Supreme Court on a personal jurisdiction dispute. That led to the Supreme Court's reversal in a groundbreaking 2017 decision in Bristol-Myers Squibb v. Superior Court of California. Though Agneshwar lost before the California Supreme Court, Arnold & Porter's website called him "the architect of the personal jurisdiction theory" in that case.

• GSK lawyer Cheffo: won significant rulings for Pfizer from the U.S. Court of Appeals for the Third Circuit and U.S. Court of Appeals for the Fourth Circuit challenging plaintiffs' expert testimony in mass torts involving cholesterol drug Lipitor and antidepressant Zoloft. He also serves as co-liaison counsel in the opioid multidistrict litigation for defendants that manufacture the pharmaceutical painkillers, and he represents bankrupt firm Purdue Pharma.

• Petrosinelli, Pfizer's lawyer: a member of his firm's executive committee, he is co-chairman of the products liability practice group. He was Pfizer's lead counsel in multidistrict litigation over anti-smoking medication Chantix and Viagra, used for erectile dysfunction.

• Schmidt, for Boehringer Ingelheim: he was lead counsel for Boehringer in multidistrict litigation over the blood thinner Pradaxa, in which he won several verdicts. He also scored two groundbreaking wins for Hoffmann-La Roche Inc. in New Jersey over acne treatment medication Accutane.