Johnson and Johnson has pulled the plug on a study aimed at getting an additional approval for its intravenous antibiotic Doribax due to "significant safety concerns".

The US Food and Drug Administration said that a recent clinical trial evaluating the effects of Doribax (doripenem) on treatment of patients with ventilator-associated pneumonia, demonstrated excess mortality and a numerically poorer clinical cure rate among subjects treated with Doribax compared to those treated with Merck & Co's off-patent drug Primaxin (imipenem-cilastatin).  

Specifically, the 274-patient study, which was actually halted in May, found that 21.5% of those treated with Doribax had died within 28 days of starting treatment, compared to 14.8% with the combination treatment. Some 45.6%-49.1% of Doribax patients were cured of pneumonia, compared with 56.8%-66.1% for the control group.

The agency, which said it is reviewing the results, reminded US doctors that Doribax is not approved to treat any type of pneumonia (although it is available for hospital-acquired pneumonia in Europe), nor is it approved for doses greater than 500mg every eight hours.

The agency stressed that Doribax, which was launched in 2007, is still considered safe and effective for its approved indications, namely treatment of adults with complicated intra-abdominal infections and complicated urinary tract infections including pyelonephritis. It is not a major drug for J&J which does not disclose sales of products that do not bring in more than $500 million per year.