HONG KONG – A criminal probe associated with allegations of manipulated data in Japan is not slowing Swiss drugmaker Novartis AG’s expansion in the market, the second largest in the world.

Japan’s Ministry of Health, Labor and Welfare filed a criminal complaint against the Swiss multinational in January saying the company had used data that may have been manipulated in advertising for blood pressure drug Diovan (Valsartan). Japan accounted for about a quarter of Diovan’s worldwide sales last year.

Novartis reported annual sales of Diovan have been higher than $954 million since 2005, but they have dropped steadily in the last half of the year to ¥22.03 (US$216 million) in the third quarter of 2013 from ¥26.14 (US$256 million) a year earlier.

On Feb. 19, authorities raided the Tokyo offices of the company. The ministry said the company exaggerated the benefits of the drug. Exaggerating drug advertisements can lead to sentences of two years in prison and fines of $19,000 but the reputational damage may be more severe.

Novartis first got into trouble when allegations arose that clinical data used in trials for its blood pressure and heart failure drug Diovan was tainted. Last July, a former employee of the company was found to have participated in a study for Diovan without disclosing his affiliation to the company.

A number of studies were then pulled back after medical schools and the ministry found data manipulation had altered the results. But Novartis advertisements for Diovan had used the results of those tainted studies to show that the drug was better than other products in the market in lowering the risk of heart attack and stroke in patients suffering from hypertension.

The company has apologized for the sequence of events, saying in a statement that it “regrets the inconvenience to patients, to healthcare professionals and to Japanese society” and that it “has already taken a number of corrective actions to make sure this never happens again.”

The company told BioWorld Asia that “it is our intent to work hard to regain the trust of physicians and patients in Japan.” To this end, it is working with the Ministry of Health, Labor and Welfare and plans to cooperate in any future investigations.

Novartis would not comment further on the investigation, saying only that it does not comment on pending legal matters, but it does plan to cooperate with prosecutors.

The legal hiccup is not stopping Novartis from expanding its presence in this mega market, the second largest in the world for the company. Since 2007, the Swiss giant “has invested in over 175 clinical studies with over 14,000 patients. In the same time period we have brought 15 new molecular entities to Japan as well as 16 extensions of labeling for new clinical indications.”

On Feb. 21 the company announced that Lucentis (ranibizumab), a drug it co-developed with the Genentech division of Basel, Switzerland-based Roche Holding AG, had received approval for a fourth indication in Japan. The drug is now approved to treat diabetic macular edema (DME).

Lucentis is the first anti-vascular endothelial growth factor therapy approved in Japan to treat DME.

DME is a major cause of loss of vision for diabetic patients. It is caused by diabetic retinopathy, which is characterized by changes in the blood vessels of the retina.