The top 10 pharmaceutical products being sold in the Japanese market, by both local and foreign players, contribute to about 10 percent of the $120 billion pharmaceutical market, says an IMS Health report. These products generated sales revenue in the range of $970 million to $1.81 billion per year, but only five of the top 10 products witnessed growth during 2011.

Plavix, Aricept and Remicade recorded 22.9 percent, 14.9 percent and 13.3 percent growth, respectively, while Takepron and Leuplin registered single digit growth. The other five products recorded negative growth and the average growth of each of these top 10 products was less than the growth rate of the pharmaceutical industry that is growing at over six percent. All the leading products have sales revenue of over $1 billion, except Remicade and Leuplin, which recorded sales revenue of $970 million each.

Aricept (donepezil), developed by Eisai, is used for palliative treatment of mild to moderate Alzheimer's disease and led the table of top 10 products with sales revenue of $1.81 billion followed by Blopress of Takeda ($1.62 billion) and diovan of Novartis ($1.51 billion). As of 2011, Aricept, co-marketed with Pfizer, was the world's best-selling Alzheimer's treatment.

Of the top 10 products, seven products are from local companies, namely Eisai, Takeda, Hisamitsu, Daiichi Sankyo and Mitsubishi Tanabe Pharma. The remaining three are from foreign companies. Three products of Takeda - Blopress, Takepron and Leuplin - have total sales of over $3.5 billion and helped it to become a leading pharmaceutical company in Japan. (Read Medical devices: A hot segment in Japan)

Blopress, ranked second, has approval from Japanese regulators for the treatment of patients with mild to moderate chronic heart failure. It has also been indicated for the treatment of hypertension and is being considered for additional indications to maximize its sales potential. Discovered by Takeda and launched in 1992 in Japan, Takepron, ranked eighth, is a proton pump inhibitor indicated for gastric ulcer, duodenal ulcer and reflux esophagitis. Takeda's Leuplin (leuprorelin acetate), ranked 10th, is an LH-RH analog that consistently stimulates the pituitary gland, resulting in suppressed production of male or female hormone. The drug was first launched for the treatment of prostate cancer in Japan in September 1992. Leuplin is used as a treatment for hormone-dependent diseases and is currently available in about 100 countries.