Updated from 5:01 p.m. EDT

Shares of

Bristol-Myers Squibb

(BMY) - Get Report

plummeted as much as 28% Wednesday on an announcement the pharmaceutical company planned to voluntarily

withdraw a request for marketing approval of antihypertensive drug

Vanlev

because of safety concerns.

In after-market trading, Bristol-Myers stock fell to 50 3/8.

Vanlev is the company's best chance of a blockbuster drug, one which could potentially compete with

Pfizer's

(PFE) - Get Report

Norvasc

drug. Indeed, some analysts believed that Vanlev originally due for a June or July launch was the only potential blockbuster drug launch of 2000.

New York City-based Bristol-Myers withdrew the drug on

Food and Drug Administration

concerns over a side effect known as angioedema, a swelling of the face, throat, lips or tongue that can be triggered by food and commonly used drugs such as ACE-inhibitors, nonsteroidal anti-inflammatory agents and some antibiotics, the company said.

Bristol-Myers, the No. 3 drugmaker in the U.S., plans to resubmit the application early next year.

"This is a very significant setback," said Richard Evans, an analyst at

Sanford C. Bernstein

. "Vanlev is the whole story

of the company. It's the centerpiece of the data on Bristol-Myers and the only reason to own the stock." He rates Bristol-Myers a market perform and his firm does no underwriting for the company.

For next year, he had projected top line growth of 7% for the company, with 3.9% of it driven by Vanlev. "Now we're looking at 2% to 3% growth if Vanlev does not come back at all," Evans added of the drug he cited as the company's key growth driver.

Both Evans and Leonard Yaffe of

Banc of America Securities

were relatively bullish on Vanlev's prospects. Yaffe had forecasted Vanlev sales at $120 million for 2000 and at $650 million, or 7 cents to 10 cents a share in earnings, for 2001. He downgraded Bristol-Myers to market performer from strong buy on news of the withdrawal and his firm has done no underwriting for the company. Evans had forecasted sales at $300 million for 2000 and at $600 million for 2001.

For his part, Evans' earnings per share estimate for 2001 currently stands at $2.53, but it will be revised significantly lower. After all, his five-year growth rate for the stock had been 13% and now it will be revised to below double-digits.

This is not the first setback for Bristol-Myers drugs this year. On March 1, the Federal Court in Newark, N.J. ruled generic products could compete with the company's cancer drug Taxol. Shares of the company fell 10% that day to close at 51 5/16.

Then, on March 17, Bristol-Myers withdrew a new drug application for UFT, a potential oral therapy for colon cancer, in order to allow more time to review ''new analyses of existing data.'' The withdrawal of the application applied to both the company's experimental UFT and a combination packet containing UFT and leucovorin pills meant to be sold under the brand name. The shares dropped 3% on March 17 to 53 7/16.

"We believe that Bristol-Myers' recent experience with NDAs is substantially related to a cautious FDA following recent product experienced including

Warner-Lambert's

(WLA)

Rezulin, Pfizer's

(PFE) - Get Report

Trovan and

Johnson & Johnson's

(JNJ) - Get Report

Propulsid," said Doug Christopher, an analyst with

Crowell, Weedon

. "When you hear about side effects, that's pretty substantial. You want to be sure to tweak the dose the right way." He continues to rate Bristol-Myers a buy and his firm has done no underwriting for the company.

Diabetes drug Rezulin was withdrawn from the market on March 21 because it caused liver toxicity. Trovan, an antibiotic, was severely restricted in 1999. And last month, Johnson & Johnson said it will

stop marketing Propulsid, a heartburn medication, in the U.S. and distribute it only to patients who have not been helped by other treatments. The FDA approved Propulsid in 1993, but the agency began receiving reports of patients dying by the next year. There have been reports of 80 deaths related to the medication.

"There's been a swing in the pendulum from 1995 to 1998 when there were accelerated approvals," Christopher commented. "But with the feedback now, maybe it got too fast when you have to pull products that are being sold to people. There's got to be political pressure to do the right thing at the FDA."