The US Food and Drug Administration has given the green light to Optimer Pharmaceuticals' antibiotic Dificid.

Dificid (fidaxomicin) has been approved for the treatment of Clostridium difficile‚Äďassociated diarrhoea (CDAD), making it the first antibacterial indicated for the disease to be approved by the FDA in nearly 30 years. CDAD rates have steadily risen over the past decade and it is estimated that more than 700,000 cases of the infection occur in the USA each year. The infection is a significant problem for the elderly in hospitals and care homes.

The thumbs-up is based on two Phase III trials involving 564 patients and compared Dificid with vancomycin, a common antibiotic used to treat CDAD. The clinical response was similar in the Dificid group compared with vancomycin in both studies.

However, the FDA noted that in some patients with CDAD, symptoms can return and in the Dificid trials, a greater number of patients treated with the Optimer drug had a sustained cure three weeks after treatment ended versus those patients treated with vancomycin.

Last month, Optimer signed a two-year co-promotion deal for Dificid with Cubist Pharmaceuticals, which is best-known for Cubicin (daptomycin), approved for the treatment of complicated skin infections and bacteremia caused by MRSA. The latter firm will receive $15 million a year for its services  and can earn up to $17.5 million over the two years if certain sales levels are achieved.

Optimer plans to hire 100 sales reps to promote Dificid to the 1,100 hospitals that account for 70% of CDAD cases in the USA. Chief executive Pedro Lichtinger said that "the recognition in our label of the Dificid superiority in sustained clinical response will allow the Optimer and Cubist field force to educate the medical community" about the advantage the product offers.