The Food and Drug Administration postponed its approval decision on Amgen Inc.'s osteoporosis treatment denosumab, since it requires more information from the drug maker.

The time taken for Amgen to meet these demands is uncertain but the executive vice president of research and development, Roger Perlmutter, said that the company has planned to respond to FDA's demands very soon.

FDA will then decide whether it needs a review of two-month or six-month before making the decision.

The shares of the company went down 2.1% to $60.05. Quiet a few on the Wall Street were expecting such a delay for the drug.

Eric Schmidt, an analyst with Cowen & Co., believes that denosumab is likely to be approved by mid-2010 and will touch sales of $200 million in 2010.

The FDA also requires a Risk Evaluation and Mitigation Strategy which includes a medication guide, a communication plan, and also a timetable for submission of assessments of the plans. Materials for such a program have already been submitted by Amgen.

The drug, Denosumab, is being reviewed for the treatment and prevention of osteoporosis in postmenopausal women and bone loss caused by hormone treatment in breast or prostate cancer.

A separate FDA response is expected by Amgen for the cancer-related application, which is being looked at as surprising since denosumab was filed using one application with only one FDA advisory committee reviewing it.