June 24 (Bloomberg) -- Watson Pharmaceuticals Inc. won U.S. approval to sell the first generic copy of Plan B, the emergency contraceptive made by Teva Pharmaceutical Industries Ltd.

The Watson medicine will be available by prescription only to women ages 17 and younger, according to a notice posted today on the Food and Drug Administration’s Web site. Teva, of Petah Tikva, Israel, has exclusive rights to an over-the-counter version of the pill for women ages 18 and older until Aug. 24, the FDA said.

Plan B, also known as “the morning after pill,” was approved in the U.S. for prescription use in 1999. After years of debate and urging by lawmakers, the drug was moved over the counter in 2006. Teva acquired Plan B with its purchase of Barr Pharmaceuticals Inc. in December. While Teva doesn’t disclose specific revenue for the product, spokeswoman Denise Bradley said in April that nonprescription use has doubled sales.

Generic drugs can cost 30 percent to 80 percent as much as the original drug, with prices falling more when there are more copies on the market. A one-time use package of Plan B costs $49.99 from Internet retailer Drugstore.com Inc. The medicine consists of two tablets of levonorgestrel taken 12 hours apart.

The FDA said April 22 that it wouldn’t stand in the way of a judge’s order to allow over-the-counter sales to 17-year-old women. Teva must formally apply with the agency to lower the age by one year, and the company continues to “work closely” with the FDA as it reviews the proposed change, Bradley said today.

Patty Eisenhaur, a spokeswoman for Corona, California-based Watson, didn’t immediately return a voice-mail message seeking comment.

To contact the reporter on this story: Catherine Larkin in Washington at clarkin4@bloomberg.net.

Last Updated: June 24, 2009 17:35 EDT