Eltrombopag for chronic immune thrombocytopenia.

摘要

Gregory Cheng and colleagues (Jan 29, p 393) report the results of a randomised, double-blind, placebo-controlled trial in patients with chronic immune thrombocytopenic purpura. They show that eltrombopag can maintain durable platelet counts and reduce risk of bleeding during a 6-month period. Since this study was done as a global clinical trial, the distribution of participants' ethnic origins warrants further consideration. In the eltrombopag group, 75% of the patients were white, 16% were Asian, and 10% were of other ethnic origins. All patients were treated with the standard starting regimen of 50 mg eltrombopag once daily with 25 mg dose adjustments (to a maximum of 75 mg) irrespective of ethnic origin. However, east Asian patients have a greater response to eltrombopag exposure, and thus require a lower dose, than do non-Asians. Indeed, according to the US Food and Drug Administration and the European Medicines Agency, the recommended dose for east Asian patients is a lower, 25 mg once-daily starting regimen. The recommended dose according to the Pharmaceuticals and Medical Devices Agency of Japan is a 12.5 mg once-daily starting regimen with 12.5 mg dose adjustments (to a maximum of 50 mg). Without these dose reductions, the incidence of adverse events might have been higher in east Asian patients in Cheng and colleagues'trial.