TOKYO, Feb 6 (Reuters) - Shares of Japanese pharmaceutical companies slumped in early Tokyo trading on Friday after U.S. President Donald Trump's website offering discounted prescription medicines went live. Sumitomo Pharma sank 4.5%, while Roche affiliate Chugai Pharmaceutical lost 3.1%. Takeda Pharmaceutical, Japan's largest drugmaker, declined 1.5%. Trump on Thursday unveiled TrumpRx.gov following deals struck with 16 of the largest global drugmakers for "most-favoured nation" prices for Americans in exchange for exemptions from U.S. tariffs. The drugmaker sector lost 1.6% to become the second-worst performer among the Tokyo Stock Exchange's 33 industry sub-indexes. (Reporting by Rocky Swift in Tokyo; Editing by Sherry Jacob-Phillips) (The article has been published through a syndicated feed. Except for the headline, the content has been published verbatim. Liability lies with original publisher.)