UPDATE 1-Pharming says anti-age drug completes Phase I study

* Phase I trial for anti-ageing drug Prodarsan completed

* Shares up 4.3 percent

* Company determining next steps in development program

(Add company comments, background)

AMSTERDAM, Nov 26 (Reuters) - Dutch biotechnology firm Pharming Group NV (PHAR.AS) has completed a Phase I study of Prodarsan, a drug made by a subsidiary for those suffering from Cockayne syndrome or premature ageing.

Shares in Pharming, which had traded flat on Wednesday before the announcement, rose 4.3 percent to 0.73 euro as of 1320 GMT.

Tests on animals with Prodarsan have shown beneficial effects and the drug could also be used to treat diseases which affect the elderly, such as dementia, the company said.

"In consultation with the regulatory authorities, we are determining the next steps to be taken for clinical development program for Prodarsan," DNage general manager Rein Strijker said in a statement.

"We look forward to begin testing the product in patients suffering from premature ageing in the near future," Stijker said. "We will also apply the same principles to start tests with various other product candidates for the treatment of ageing diseases in the elderly population."

There is no known cure for Cockayne syndrome, a rare genetic disease, where children suffer from accelerated ageing and which results in "growth failure, mental retardation, eye abnormalities and a reduced life expectancy," Pharming said in a statement.

Prodarsan is being tested by Pharming's wholly-owned subsidiary DNage. (Reporting by Reed Stevenson; Editing by David Holmes)