Shire Pharmaceuticals Group plc announced that the United States Food & Drug Administration (FDA) Pediatric Board has granted an additional six months exclusivity for Agrylin (anagrelide hydrochloride), the company's treatment for essential thrombocythemia and other myeloproliferative disorders in which excess platelets are produced, leading to abnormal blood clotting or bleeding.

This extension provides US market exclusivity for the drug, under the Hatch-Waxman ruling, until mid September 2004. The extension is a result of the FDA's determination that Shire has met the terms of the written request upon review of the study data from a clinical programme examining the effect of the drug in paediatric patients.

In 2003, sales of Agrylin amounted to $132.5m, the majority of which were in the US since the drug, although approved in several other countries, is currently available on a named patient basis only in Europe. First quarter worldwide sales of the drug in 2004 were $38.3 million (for the period ended March 31 2004). IMS data shows that Agrylin had a 27 per cent share of the US hydrea and generic hydroxyurea prescription market in March 2004.