Effect of anagrelide on platelet count and function in patients with thrombocytosis and myeloproliferative disorders.
BACKGROUND
Anagrelide is a quinazolin compound developed initially as an inhibitor of platelet aggregation. Since "in vivo" studies demonstrated that it was responsible for thrombocytopenia in humans, anagrelide has been used recently in a small number of patients with thrombocytosis and myeloproliferative disorders. Platelet count was well controlled in the large majority of patients, and only minimal side effects were observed.


METHODS
Eight patients (5 with essential thrombocythemia, 2 with chronic granulocytic leukemia, and 1 with idiopathic myelofibrosis) received anagrelide (induction dose 4 mg/die; mean maintenance dose 2 mg/die; mean observation time 26 weeks). Complete blood counts were determined 4 times during the first month, and subsequently every month. "In vivo" and "ex vivo" platelet function was studied before anagrelide and after 4 and 10 days of therapy.


RESULTS
Platelet count was reduced and maintained below 500 x 10(9)/L in 5 of 8 patients. Headache, palpitation/tachycardia, gastrointestinal symptoms and a decrease in hemoglobin were the side effects. Anagrelide did not modify the leukocyte count or "in vivo"/"ex vivo" platelet function.


CONCLUSIONS
Anagrelide may control thrombocytosis in patients with myeloproliferative disorders, even when traditional drugs have failed. When required, anti-aggregating drugs may be associated with anagrelide, since it has no effect on platelet function.
Balduini
C L
CL
Dipartimento di Medicina Interna, Università di Pavia, Italy.
Bertolino
G
G
Noris
P
P
Ascari
E
E
D000328:Adult; D000368:Aged; D004341:Drug Evaluation; D005260:Female; D006801:Humans; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000188:drug therapy*; D008297:Male; D008875:Middle Aged; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology*; D010976:Platelet Count / Q000187:drug effects*; D055728:Primary Myelofibrosis / Q000188:drug therapy; D011799:Quinazolines / Q000494:pharmacology / Q000627:therapeutic use*; D013920:Thrombocythemia, Essential / Q000188:drug therapy*
D010975:Platelet Aggregation Inhibitors; D011799:Quinazolines; C021139:anagrelide