A Food and Drug Administration reviewer who has accused the agency of being lax in monitoring drug safety on Thursday said five medicines on the market need closer scrutiny for possible side effects.

Shares of several makers of the drugs, including British rivals GlaxoSmithKline Plc and AstraZeneca Plc fell sharply after the testimony.

Dr. David Graham, speaking at a Senate hearing, singled out Abbott Laboratories Inc.‘s weight-loss drug Meridia, AstraZeneca’s cholesterol fighter Crestor, Pfizer Inc.‘s arthritis treatment Bextra, Roche’s acne drug Accutane and GlaxoSmithKline’s asthma drug Serevent.

“There are at least five drugs on the market today that I think need to be looked at quite seriously to see if they belong there,” said Graham, associate director for science in the FDA’s Office of Drug Safety.

Graham in August presented his own FDA-sponsored study suggesting Merck & Co’s arthritis drug Vioxx caused heart attacks and stroke, the month before Merck recalled its $2.5 billion-a-year drug. Graham has alleged senior FDA officials tried to suppress his presentation.

“David Graham was the FDA researcher who had questioned Vioxx’ safety before it was recalled, so a list of drugs he’s also concerned about is going to be taken quite seriously,” said David Moskowitz, an analyst at Friedman, Billings, Ramsey & Co.

A top official at the FDA’s Office of New Drugs on Thursday, however, disagreed with Graham’s list of problematic medicines.

“I do not have reason to believe that set of five drugs is specifically more concerning,” Dr. Sandra Kweder, deputy director of the Office of New Drugs, told the Senate Finance Committee hearing.

Bextra is in the same class of drugs as Vioxx, which was recalled Sept. 30 after a company study showed it doubled heart attack and stroke risk.

The FDA is planning to look at the entire family of Vioxx-type drugs at an advisory committee meeting next year, including Pfizer’s older Celebrex arthritis treatment.

“I would be looking at Bextra very, very carefully,” Graham said at the hearing, which was called to examine the actions of the FDA and Merck surrounding Vioxx.

Pfizer last week said it is considering a “black box” warning on Bextra’s package insert label that the drug can cause a rare but sometimes fatal skin disorder called Stevens-Johnson syndrome. The pill, launched in 2001, had sales of $687 million last year.

Serevent is used by itself and also as one of two ingredients in GlaxoSmithKline’s asthma treatment Advair, the company’s biggest product with sales of $4 billion a year.

Graham said he was worried about reports Serevent might increase the chances of dying. Serevent carries a warning of rare cases of asthma-related fatalities in studies. Glaxo officials were not immediately available for comment.

Shares of GlaxoSmithKline were off 3 percent at $43.66 on the New York Stock Exchange.

AstraZeneca last year launched Crestor as a challenger to Pfizer’s Lipitor. The new drug had global third-quarter revenue of $260 million. Graham said there was a need for a serious look at the chances for Crestor to cause kidney failure and a potentially fatal muscle breakdown.

“The FDA to date has not given us any indication of a major concern regarding Crestor,” said AztraZeneca spokeswoman Rachel Bloom-Baglin.

Roche’s Accutane, also sold generically under the name isotretinoin, has been on market for 22 years and is reserved for the most severe forms of acne that are not responsive to other treatments. It can cause birth defects.

“Over the years a strong risk management program has evolved with the drug to make sure it is used appropriately,” said Roche spokeswoman Carolyn Glynn. She said the drug is expected to have sales of about $84 million this year.

Graham said Abbott’s Meridia diet drug only works if used long-term, but many people stop taking it early on because of side effects. “Is there a need for this product in the first place?” he asked.

Abbott spokesman Tim Lindberg defended Meridia as a “safe” treatment for obesity.