Jan. 30 (Bloomberg) -- Takeda Pharmaceutical Co. won U.S. approval to sell a new version of the acid-reflux treatment Prevacid, the Japanese drugmaker’s second-biggest medicine.

The pill, called Kapidex, was cleared by the Food and Drug Administration for ailments such as chronic heartburn caused when excess stomach acid backs up into the esophagus, the company said today in an e-mailed statement. The new formulation releases the drug in two separate stages, spreading out the dose evenly.

Regulators took three months longer than scheduled to decide whether to approve the new medicine, dexlansoprazole. The existing Prevacid accounted for 19 percent of Takeda’s revenue in the quarter that ended Sept. 30. President Yasuchika Hasegawa, 62, is counting on the new one to buffer an expected decline in sales after the original loses patent protection in November.

Prevacid, given once a day, is most often sold as a capsule or tablet and belongs to a class of drugs known as proton-pump inhibitors, which block acid-producing enzymes on the stomach wall. Almost 19 million Americans suffer from the acid backup, called gastroesophageal reflux disease, according to Takeda. In the worst cases, the reflux can damage the esophagus.

Takeda, Asia’s largest drugmaker, submitted data to the FDA in December 2007 from six final-stage trials of about 6,000 patients in 20 countries.

Similar products include AstraZeneca Plc’s Nexium, Eisai Co.’s Aciphex and Wyeth’s Protonix, now a generic. Procter & Gamble Co. also sells over-the-counter Prilosec, once the world’s best-selling medicine, in the U.S.

The shares of Takeda, which is based in Osaka, fell 29 percent last year, compared with a 23 percent decline for the MSCI World Health-Care Index of 115 companies.

---Editors: Robert Greene, Andrew Pollack

To contact the reporters on this story: Kanoko Matsuyama in Tokyo at kmatsuyama2@bloomberg.net; Catherine Larkin in Washington at clarkin4@bloomberg.net.

Last Updated: January 30, 2009 18:57 EST