A U.S. Food and Drug Administration scientist who has accused the agency of being lax in monitoring drug safety told a Congressional hearing that the anti-obesity drug Meridia (sibutramine) is one of five prescription medications on the market that need closer scrutiny.

Dr. David Graham, associate director for science in the FDA's Office of Drug Safety. testified at a Senate hearing that the weight loss drug Meridia only works if used long-term, but many people stop taking it early on because of side effects.

The most worrisome side effect of the drug is that it can raise heart rate and blood pressure.

Abbott Laboratories’ patient information warns Meridia patients of primary pulmonary hypertension (PPH), which has no known cause but is a rare and sometimes fatal disease. PPH causes high blood pressure in the lungs that leads to a feeling of constant breathlessness with minimal exertion, fatigue, dizzy spells, fainting, and chest pain.

Meridia, sold in 70 countries, has been used by 15 million people worldwide since 1997. Abbott has admitted that at least 32 patients have died while taking Meridia.

Italy was the first country to act on the adverse side effects from the drug after two cardiovascular deaths and 50 reports of health related problems. Suspension of the sale of subutramine led to a Europe wide safety review of the diet drug.

In Britain, two deaths have been attributed to the use of Meridia and 103 total serious adverse side-effect reports were made in France and in Great Britain.

"Is there a need for this product in the first place?" Graham asked in his testimony before the Senate panel.

Abbott Laboratories issued a statement defending Meridia. "Obesity remains one of the leading health epidemics in the U.S., and Meridia is one of the few effective drugs that are currently available," it said.