When
corticosteroid therapy, immunoglobulin and
splenectomy fail to control chronic
idiopathic thrombocytopenic purpura and the risk of
bleeding remains high,
romiplostim is an acceptable option but close monitoring is needed to evaluate long-term risks.
Eltrombopag (
Revolade, GlaxoSmithKline) is a synthetic non-
peptide agonist of endogenous receptors for
thrombopoietin, a platelet
growth factor. Clinical evaluation of
eltrombopag in this setting is mainly based on a double-blind placebo-controlled trial in a heterogeneous group of 114 patients. The platelet count rose to at least 50,000/mm3 for five weeks in about one-quarter of patients receiving oral
eltrombopag 50 mg/day. An indirect comparison providing weak evidence suggests that
romiplostim is more effective. Clinical trials did not provide evidence that either
drug reduced the frequency of
bleeding. The haematological risks associated with
eltrombopag are poorly evaluated, and mainly include:
thrombosis, bone marrow disorders, and aggravation of
thrombocytopenia after
drug withdrawal. Aggravation of
myelodysplastic syndrome cannot be ruled out in the long term. Hepatic disorders such as photosensitisation are frequent. The risk of
cataract formation and renal impairment requires further study. There appears to be a high risk of pharmacokinetic interactions through a variety of mechanisms, including
enzyme competition and
cation binding, but this risk is not well documented.
Eltrombopag is administered orally, making it more convenient than
romiplostim, which necessitates weekly
subcutaneous injections. In practice, when standard treatments fail in patients with chronic
idiopathic thrombocytopenic purpura and a high risk of
bleeding, it is better to use
romiplostim, which appears to be somewhat more effective than
eltrombopag.
Eltrombopag also seems to carry a higher risk of non-haematological adverse effects and drug interactions.