The Food and Drug Administration has declined to approve an oral contraceptive and a glaucoma treatment being developed by Merck & Co Inc, but the drugmaker did not disclose details of the agency's concerns.

Merck already sells both products in some overseas markets. The contraceptive, called NOMAC/E2, is a pill that combines two hormones. The glaucoma medicine, tafluprost, is also known by its brand name Saflutan.

Merck buried mention of the two setbacks in a 62-page regulatory filing with the Securities and Exchange Commission, saying it received so-called complete response letters from the FDA for both products.

Such letters indicate the FDA is not yet willing to approve an experimental product and often cite shortcomings of the product or the agency's need for more clinical trial data or additional analysis of such data. Drugmakers are not required to share such details with the public or with stockholders.

Merck did not issue news releases about the FDA refusals, but instead briefly noted them two thirds of the way into the quarterly filing.

Drugmakers typically issue news releases announcing complete response letters, with varying levels of detail about FDA concerns or requirements.

"We're not commenting beyond what's been disclosed" in the complete response letters, a Merck spokesman said, noting the company plans to have further discussions with the FDA in regard to the letter.

Merck said it received the complete response letter regarding the contraceptive on November 4, three days before the letter involving its glaucoma medicine.

The setbacks come just a day ahead of Merck's annual meeting at company headquarters with analysts and money managers, to review its pipeline of experimental products.

Merck also noted in the filing that it had discontinued development of MK-0431C, a pill pairing Merck's Januvia diabetes drug with the active ingredient of Actos (pioglitazone), a diabetes treatment sold by Takeda Pharmaceutical Co Ltd.