The long and short of fat

With patent protection for Roche'sXenical orlistat set to expire in 2009, the obesity drug's $531 million in 2007 sales will soon be up for grabs. Now, two mouse studies make a case for blocking receptors for free fatty acids-short chain in one case and long chain in the other-that are downstream of Xenical's target. Although some drug developers already have explored brain- and pancreas-specific homologs of one of these receptors to treat metabolic diseases, hitting the intestinal version could bypass some of Xenical's side effects while still blocking fat absorption.

Xenical works by blocking pancreatic lipase, an enzyme secreted into the intestine that liberates dietary fatty acids from a triglyceride precursor form, causing triglycerides to pass through the digestive tract...