Shire Pharmaceuticals’ legal and marketing battles with generic firms has hotted up following the news that the US Food and Drug Administration has granted marketing approval for the sale of generic versions of the UK-based group’s Agrylin (anagrelide) for the treatment of thrombocythemia.

Major US generic players Ivax, Barr, Mylan and Impax all issued statements to the effect that the agency has given approval to their Abbreviated New Drug Application for anagrelide capsules in 0.5mg and 1mg dosage strengths, adding that they intend to begin marketing the product immediately.

The move is sure to cannibalise Shire’s sales of Agrylin, which contributed $153 million to the firm’s turnover in 2004, a 15% increase on the year before. Estimates vary how much of that total comes from the USA, but it is believed to be in the region of $105 million to $109 million.

Shire is also set to come face-to-face with Impax over patent disputes concerning Adderall XR (amphetamine salts extended release) but not for some time yet. Shire had two cases pending against Impax [[05/01/04d]], [[14/01/05b]], and the first was due to heard in October this year but a Delaware District court has now set a date for both cases, which will be February 23, 2006.

Adderall is comfortably Shire’s best-selling product with sales last year of over $600 million, and the company, which says it is committed to protecting patents it has on the drug, will be content with the delay. Shire has patent protection on Adderall up to 2018, but the ANDAs are already been prepared.

Shire has a lawsuit pending against Barr, which was the first firm to send a notice letter about its filing for generic Adderall, but decided not to sue other potential competitors Colony Pharmaceuticals and Teva [[12/04/05d]].