Medivation Inc., a biotechnology company working on drugs to treat prostate cancer and Alzheimer's disease, on Friday re-affirmed its financial guidance for this year and said it continues to believe it will have the cash to fund its operations through at least 2012, when it hopes to have completed advanced clinical trials.

The announcements came as the San Francisco-based company reported that it narrowed its first-quarter loss even as its revenue fell. The net loss was smaller than analysts expected, but Medivation's revenue fell short of predictions, and its shares slipped after hours Friday.

The shares fell 39 cents, or 1.7 percent, to $22.40 in extended trading, after the results were reported. They had gained 88 cents, or 4.0 percent, to finish the regular trading session at $22.79.

Medivation said after the market closed that its net loss was $8.5 million, or 24 cents per share. That was better than the loss of 27 cents per share analysts expected, according to FactSet. A year ago, Medivation lost $17.5 million, or 51 cents per share.

Revenue fell 7 percent to $14.7 million. Analysts were expecting $16.1 million, according to FactSet.

The company is developing its prostate cancer drug with Astellas Pharma Inc. and its drug to treat Alzheimer's disease and Huntington disease with Pfizer Inc. Medivation has funded itself through sale of the company's stock and from payments from Astellas and Pfizer.

The company's cash, cash equivalents and short-term investments as of the end of March was $195.0 million, down from $207.8 million at the end of 2010.

The company's CEO, David Hung, said in a statement that the company's "existing cash is adequate to fund our operations beyond the end of 2012, which we expect to be more than sufficient time to complete and report data from our ongoing Phase 3 trials in post-chemotherapy advanced prostate cancer and in Alzheimer's disease."

The company reiterated its forecast for operating expenses of $100.0 million to $110.0 million in 2011, excluding cost-sharing payments from Astellas and Pfizer.