Last Updated: 2007-04-02 14:00:43 -0400 (Reuters Health)

March 30 (Reuters) - The U.S. withdrawal of Novartis AG's Zelnorm treatment for irritable bowel syndrome highlights the sometimes narrow dividing line between success and failure in the pharmaceutical industry.

Pulling a medicine from the market can be devastating for companies, since it cuts revenues and leaves firms exposed to potentially huge liability claims.

Following is a list of some major drugs that have been withdrawn in recent years due to safety concerns:

-- BEXTRA, Pfizer Inc. (2005)

Pfizer suspended sales of arthritis drug Bextra in April 2005 after U.S. and European regulators said the risk of serious side effects, including a potentially fatal skin allergy, outweighed the benefits.

-- TYSABRI, Biogen Idec, Elan Corp. (2005)

The companies suspended sales of the multiple sclerosis drug in February 2005 after a patient died from a rare and often fatal infection of the central nervous system. U.S. regulators cleared Tysabri to return to the market last year, with restrictions.

-- VIOXX, Merck & Co. (2004)

The $2.5 billion a year pill for arthritis sufferers was pulled in September 2004 after a study showed it doubled the risk of heart attack and stroke after 18 months of use.

-- BAYCOL, Bayer AG (2001)

Bayer's cholesterol-lowering medicine was withdrawn in August 2001 after being linked to a severe muscle condition called rhabdomyolysis and more than 100 deaths.

-- LOTRONEX, GlaxoSmithKline Plc (2000)

GlaxoSmithKline pulled its drug for the treatment of irritable bowel syndrome from the market amid safety concerns in November 2000. The medicine was reintroduced in November 2002, but with severe restrictions which have limited its use.

-- PROPULSID, Johnson & Johnson (2000)

The heartburn drug was taken off the U.S. market in July 2000 after the Food and Drug Administration warned that it could cause irregular heartbeats and sudden death.

-- REZULIN, Pfizer (2000)

The diabetes drug was withdrawn in March 2000 after about 100 people who took it had to have liver transplants or died from acute liver failure.

-- REDUX AND PONDIMIN, Wyeth (1997)

Two medicines in the "fen-phen" diet drug cocktail were recalled in 1997 after being linked to heart valve damage among some of the 6 million Americans who took them.