Regulatory news injured a few biotech stocks on Monday, while others got a kick out of positive clinical news -- the balance a kind-of-down day for the sector.

Vanda

(VNDA) - Get Report

shares tanked after the Food and Drug Administration issued a

non-approvable letter

for its lead candidate, antipsychotic drug iloperidone. Shares gave up $2.46, or 73%, to 90 cents. The FDA requested an efficacy study that could take up to a year and a half and cost $35 million, as well as additional long-term safety data that could take two years to complete.

The company said in a conference call that under the capital available to the company today, it would not be able to conduct both the additional efficacy study and the additional safety exposures, but its first step is more discussions with the FDA to clarify the agency's thinking and any alternatives.

Meanwhile,

Mylan

(MYL) - Get Report

said Monday that its subsidiary received final FDA approval for its abbreviated new-drug application (ANDA) for three strengths of the generic version of

Sciele Pharma's

( SCRX) hypertension drug Sular. Sular, in the three strengths for which the generic was approved, generated U.S. sales of $94 million for the 12 months ended March 31, according to Mylan.

Mylan said it's shipping its Nisoldipine ER, the first generic version of Sular in the U.S., immediately. Sciele shares declined $3.45, or 16.8%, to $17.15. Mylan shares, incidentally, also lost ground, falling 52 cents, or 3.9%, to $12.74.

More regulatory news, Bayer HealthCare Pharmaceuticals and

Onyx Pharmaceuticals

(ONXX)

said Monday that the State Food and Drug Administration (SFDA) of China has approved Nexavar tablets for patients with unresectable or metastatic hepatocellular carcinoma (HCC), or liver cancer.

Onyx shares traded up $1.21, or 3.1%, to $40.09.

In earnings, look for

Amgen

(AMGN) - Get Report

after the close. But rather than quarterly digits, the big story is its bone drug denosumab, which reduced the risk of spine and hip fractures compared to placebo in a large phase III study of postmenopausal women with osteoporosis. The

much-awaited results

regarding the potential blockbuster drug sent the stock up $6.56, or 12.2%, to $60.48 Monday.

Elsewhere,

Biocryst

(BCRX) - Get Report

said Monday that according to preliminary results from a midstage study, patients with influenza who were treated with intravenous-administered flu treatment peramivir had a statistically significant improved median time to alleviation of symptoms vs. the placebo arm in an outpatient setting.

The company said that according to the trial, which was conducted by its partner, Shionogi & Co., in Japan, the drug was also safe and well-tolerated. Shionogi has begun preparing for a late-stage trial of the drug. Biocryst shares traded up 53 cents, or 20.2%, to $3.15.

Vanda, Sciele, Onyx, Amgen and Biocryst are all components of the Nasdaq biotechnology index, which edged down 0.2% to 886.69.