Merck said it would not submit its osteoporosis treatment odanacatib to U.S. regulators until next year. Jefferies analyst Jeffrey Holford said the delay "will disappoint many investors," and hurt shares today.

"We continue to believe in potential of this drug, and look forward to filing it in 2014," Chief Executive Officer Kenneth Frazier said in a conference call with industry analysts who expressed concern about the delay.

Shares slumped 2.7 percent in premarket trading Friday after closing at $43.25 on Thursday.

Merck research chief Peter Kim told analysts he had seen complete data from a big late-stage trial of the novel drug. But he said the company would delay the marketing application in order to submit data from an "extension" trial, or a followup observation of patients who had completed the study.

Merck executives did not cite any specific safety or effectiveness issues relating to the medicine.

The No. 2 U.S. drugmaker earned $1.4 billion, or 46 cents per share, in the fourth quarter. That compared with $1.51 billion, or 49 cents per share, a year earlier, when it took charges for acquisition and restructuring expenses.

Excluding special items, Merck earned 83 cents per share. Analysts, on average, expected 81 cents, according to Thomson Reuters I/B/E/S.

Global company sales fell 5 percent to $11.74 billion, hurt by generic competition for its Singulair asthma drug, but still beat analysts' estimated sales of $11.48 billion.

The company forecast 2013 earnings of $3.60 to $3.70 per share, excluding special items. The midpoint of that range is below analysts' estimate of $3.68 per share. The company earned $3.82 per share in 2012.

Merck predicted its sales in 2013 would be similar to 2012 levels, excluding foreign exchange factors, as Singulair generics continue to take their toll.

"Merck's 2013 (earnings) guidance was a bit conservative, which could point to higher expenses" this year, said Judson Clark, an analyst with Edward Jones. But he said the company's flat sales forecast was welcome because analysts were expecting somewhat lower sales.

Clark predicted Merck's earnings would rebound next year to grow in the high-single digit range, as experimental drugs are approved and bring in new revenue.

"We think Merck has one of the best drug pipelines in the industry and that it will drive growth," Clark said.

Merck, whose $6 billion-a-year Singulair lost U.S. marketing exclusivity in August, is girding for more pain from cheaper copycats. Its Maxalt migraine drug, with $600 million in annual sales, goes generic in December, and its near-blockbuster Temodar brain cancer medicine faces generics next year.

Merck said Friday it aims to seek marketing approval this year for five drugs, including suvorexant for insomnia.

It is counting on the new drugs to help cushion plunging sales of Singulair, Maxalt and Temodar.

Merck suffered a major setback in January, when an experimental cholesterol drug called Tredaptive failed to prevent heart problems and raised safety concerns. The drug, which was expected to become a big seller in the United States, was recalled in Europe following the negative study findings.

Singulair sales plunged 67 percent in the quarter to $480 million. Combined sales of diabetes drugs Januvia and Janumet rose 18 percent to $1.6 billion, fueled by growth in the United States and Japan. Sales of Gardasil jumped 61 percent to $442 million, helped by higher public sector purchases and demand in Japan and emerging markets.

(Editing by Gerald E. McCormick, Jeffrey Benkoe and Bernadette Baum)

By Ransdell Pierson