Novartis says it is likely to face criminal charges in Japan relating to manipulation of data by an employee on its blood pressure blockbuster Diovan.

The long-running problem stems from data manipulation of a post-marketing trial of Diovan (valsartan) conducted by a team at Kyoto Prefectural University of Medicine led by a former professor whose published papers on valsartan were withdrawn from medical journals after questions were raised over the validity of the findings.

The study also involved statistical analysis by a former Novartis employee, Nobuo Shirashi, who took part in other trials of valsartan at Japanese universities without disclosing any affiliation with the company. Now the Tokyo District Prosecutor's Office has disclosed that it will proceed with charges against Mr Shirahashi regarding the publication of an article containing the manipulated data.

However, “under the dual liability characteristic of the Japan legal system”,  Novartis says it will be charged as well for allegedly failing to oversee an employee. The charge carries with it a maximum fine of 2 million yen (about $19,700). Mr Shirahashi has also been re-arrested “for further investigation”.

Novartis Pharmaceuticals chief David Epstein responded by saying that the firm has “already undertaken decisive action to address problems with the company's investigator-initiated trial (IIT) research programmes in Japan””. He added that “we are committed to changing the culture” at the local unit  “and demonstrating ethical leadership among pharmaceutical companies in Japan”.

In April, Novartis announced several measures “designed to identify and correct all issues with IITs in Japan”, including the replacement of the unit’s senior management team, “a comprehensive third-party review of the company's IITs, and ongoing remedial training to ensure compliance with the company's code of conduct”.

Ranbaxy’s generic Diovan

As for Diovan, this week has seen Indian drugmaker Ranbaxy Laboratories has won US approval to produce a generic version of the drug. It was set to begin production at the end of 2012, but the facility in India that was to produce the drug was preventing from exporting to the USA by the Food and Drug Administration.

Now the agency has given the green light to manufacturing at its New Jersey-based subsidiary Ohm Laboratories. It is estimated that Novartis earned about $100 million each month for the last 20 months thanks to the absence of a generic rival for Diovan, which went off-patent in September 2012.