The U.S. Food & Drug Administration (FDA) has said that the weight loss drug Orlistat, a gastrointestinal lipase inhibitor marketed by Roche Pharmaceuticals as the prescription drug Xenical and by GlaxoSmithKline as the over the counter (OTC) drug Alli, may cause liver damage. The FDA has received 32 reports of liver toxicity, six deaths and is investigating whether to take regulatory action.

What is Orlistat?

Orlistat is a gastrointestinal lipase inhibitor also known as tetrahydrolipstatin. It is designed to treat obesity by preventing the absorption of fats in diets and thereby reducing caloric intake. It works by inhibiting gastric and pancreatic lipases, the enzymes that break down triglycerides in the intestine. When lipase activity is blocked, triglycerides from the diet are not hydrolyzed into absorbable free fatty acids and the human body excretes them undigested instead.

Marketed by Roche Pharmaceuticals as the prescription drug Xenical (Orlistat 120 mg, approved by the FDA in 1999) and by GlaxoSmithKline as the OTC drug Alli (Orlistat 60 mg, approved by the FDA in 2007), Orlistat is are available in over 100 countries.

Reports of liver toxicity

The FDA said it has received 32 reports of liver toxicity in patients using Oristat drugs from 1999 to 2008. Twenty seven of those reports involved patients who were hospitalized due to serious side effects and at least six involved patients who experienced liver failure. Although isolated cases of liver problems have been previously reported, Orlistat was on the FDA's June 2009 quarterly list of drugs that were under investigation for potential safety issues or new safety information because it had a potential signal of serious risk.

The FDA's ongoing communication update on August 24, 2009 says that its investigation is continuing. It reported that:

Between 1999 and October 2008, 32 reports of serious liver injury, including 6 cases of liver failure, in patients using orlistat were submitted to FDA’s Adverse Event Reporting System. Thirty of the 32 reports occurred outside the United States. The most commonly reported adverse events described in the 32 reports of serious liver injury were jaundice (yellowing of the skin or whites of the eyes), weakness, and abdominal pain. Hospitalization was reported in 27 of the 32 cases.

In addition to the 32 reported cases, this issue was discussed at the CDER Drug Safety Oversight Board in April 2009, and FDA is reviewing other data on suspected cases of liver injury submitted by the manufacturers of orlistat. FDA’s analysis of these data is ongoing and no definite association between liver injury and orlistat has been established at this time.

To view the FDA's press release, please click here.

FDA recommendations

Although the FDA is not yet advising healthcare professionals to change their prescribing practices, it says that consumers should, “[C]onsult their health care professional if they are experiencing symptoms possibly associated with the use of orlistat and development of liver injury, particularly weakness or fatigue, fever, jaundice or brown urine. Other symptoms may include abdominal pain, nausea, vomiting, light-colored stools, itching or loss of appetite.”

If you believe that you may have been injured due to Orlistat, contact a products liability attorney to discuss your situation and evaluate your options. You may be entitled to compensation.