Treatment of essential thrombocythemia with anagrelide.

Essential thrombocythemia (ET), the most common of the chronic myeloproliferative disorders, is characterized by thrombotic and hemorrhagic complications. Thrombotic complications predominate, endangering especially the older population and those with prior history of thrombotic episodes. However, because the life expectancy of ET patients is generally of normal length, caution must be exercised in treating these patients, and the complications of treatment must be weighed against the complications of the disease. Historically, most drugs used in the treatment of ET, such as alkylating agents and radiophosphorus, were carcinogenic themselves. Even hydroxyurea has recently come under investigation for its long-term mutagenicity. The newest drug, anagrelide, approved in March 1997 specifically for ET, appears to be safe and well tolerated.