Regulators in the USA have granted an extension to the label on Eli Lilly’s Symbyax, its combination of Zyprexa and Prozac, making it the first drug to be approved for treatment-resistant depression.

The new indication for Symbyax (olanzapine and fluoxetine), which was approved by the US Food and Drug Administration in 2003 for bipolar depression, is specifically for the treatment of adults with major depressive disorder who have not responded to two separate trials of different antidepressants. As well as the single-pill approval, the FDA has authorised the use of the antipsychotic Zyprexa (olanzapine), in combination with Prozac (fluoxetine) for bipolar depression and TRD.

The approvals are good news for Lilly, seeing as how Prozac has been off-patent for some time, while Zyprexa, still a huge earner for the company, is facing generic competition overseas. Furthermore Zyprexa has suffered from concerns that the drug causes weight gain and increases the risk of diabetes.

To that end, Lilly also noted that it has updated the Symbyax and Zyprexa labels to include additional information regarding weight gain, hyperglycaemia, and hyperlipidemia following the FDA's review of clinical trial data that the company submitted to the agency between August 2007 and July 2008. Cherri Miner, Lilly neuroscience senior medical director, said that the new indications “confirm that these medications are valuable tools for patients in the fight against severe and disabling mental illness, and expand treatment options for prescribers and patients”.

Arzoxifene superior to Evista
Meantime, Lilly has also unveiled promising late-stage data on arzoxifene, its investigational osteoporosis drug which suggests superiority over its-already marketed drug Evista (raloxifene).

Specifically, the 320-patient Phase III trial showed that arzoxifene, a selective oestrogen receptor modulator, was superior to raloxifene at increasing bone mineral density in the lumbar spine, total hip and femoral neck, and at suppressing bone turnover. The data, which were presented at the European Society for Clinical and Economic Aspects of Osteoporosis and Osteoarthritis in Athens, Greece, also noted that more women reported bronchitis and nasopharyngitis in the arzoxifene group versus those on Evista, but less new or worsening hot flushes.

The company is studying arzoxifene for the prevention and treatment of osteoporosis in postmenopausal women and the reduction of invasive breast cancer in women with osteoporosis or low bone mass. Evista, still a big-earner for Lilly, loses patent protection in the USA in 2014.