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Essential Thrombocytosis Medication

  • Author: Asheesh Lal, MBBS, MD; Chief Editor: Emmanuel C Besa, MD  more...
Updated: Nov 06, 2015

Medication Summary

Treatment for essential thrombocytosis (primary thrombocythemia) commonly includes the use of hydroxyurea, which is an antimetabolite similar in structure to naturally occurring compounds required for normal cell function. This structural similarity allows many of the antimetabolites to serve as substrates for important cellular enzymes. These substrates inhibit cell replication by direct inhibition of the enzymes needed for DNA replication or DNA repair or by incorporating directly into DNA.

Tumors and healthy cells with high growth fractions (eg, bone marrow) are sensitive to inhibition by the antimetabolites. Anagrelide is an imidazoquinazoline drug that inhibits platelet aggregation. Anagrelide appears to decrease platelet counts by decreasing platelet production.

Interferon alfa is a biologic response modifier, and32 P is a radionuclide with direct myelosuppressive properties. Interferon alfa is not known to be teratogenic and does not cross the placenta, perhaps making it safe for use during pregnancy. Platelet counts rebound in most patients after stopping interferon. Platelet counts are reduced to less than 600,000/μ L in 90% of cases after 3 months. Adjust drug dosing to achieve a platelet count within the reference range (target range, < 450,000/μ L).

Low-dose aspirin may be used to control microvascular symptoms.

Consider the patient's age, status, and adverse effect profile, in addition to the drug's cost, when choosing the treatment agent.[33]



Class Summary

Antimetabolites are similar in structure to the naturally occurring compounds required for the normal function of a cell. This structural similarity allows many of the antimetabolites to serve as substrates for important cellular enzymes, and they inhibit cell replication by direct inhibition of the enzymes needed for DNA replication or repair or by incorporating directly into DNA. Tumors and normal cells with high growth fractions (eg, bone marrow) are sensitive to inhibition by the antimetabolites.

Hydroxyurea (Hydrea)


Inhibitor of deoxynucleotide synthesis and one of the drugs of choice for inducing hematologic remission in chronic myelogenous leukemia. Less leukemogenic than alkylating agents (eg, busulfan, melphalan, chlorambucil). Myelosuppressive effects last a few days to a week and are easier to control than those of alkylating agents; busulfan has prolonged bone marrow suppression and can cause pulmonary fibrosis. The dose can be administered as a single daily dose or divided into 2-3 doses at higher dose ranges. Changes in blood cell counts may take 3-4 d to be apparent after a change in the drug dose.



Class Summary

Imidazoquinazoline agents cause suppression of megakaryocytes and decrease in platelet counts without affecting other hematopoietic cell lines.

Anagrelide (Agrylin)


Mechanism by which anagrelide reduces blood platelet count remains under investigation. Inhibits cyclic nucleotide phosphodiesterase and the release of arachidonic acid from phospholipase, possibly by inhibiting phospholipase A2. Effective in polycythemia vera with elevated platelet counts. Studies in patients support a hypothesis of dose-related reduction in platelet production, resulting from a decrease in megakaryocyte hypermaturation.


Biologic response modifiers

Class Summary

The exact mechanism of action of biologic response modifiers is undetermined. These agents may be beneficial because of myelosuppressive and antiproliferative effects.

Interferon alfa (Roferon-A, Intron A)


Myelosuppressive protein product manufactured by recombinant DNA technology. Mechanism of antitumor activity is not clearly understood; however, direct antiproliferative effects against malignant cells and modulation of host immune response may play important roles.



Class Summary

Radionuclides have myelosuppressive properties.



A beta particle emitter, which is myelosuppressive. Affects all cell types.

Contributor Information and Disclosures

Asheesh Lal, MBBS, MD Physician, Department of Internal Medicine, Lexington Medical Center

Asheesh Lal, MBBS, MD is a member of the following medical societies: American Society of Clinical Oncology, American Society of Hematology

Disclosure: Nothing to disclose.

Specialty Editor Board

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Received salary from Medscape for employment. for: Medscape.

Marcel E Conrad, MD Distinguished Professor of Medicine (Retired), University of South Alabama College of Medicine

Marcel E Conrad, MD is a member of the following medical societies: Alpha Omega Alpha, American Association for the Advancement of Science, American Association of Blood Banks, American Chemical Society, American College of Physicians, American Physiological Society, American Society for Clinical Investigation, American Society of Hematology, Association of American Physicians, Association of Military Surgeons of the US, International Society of Hematology, Society for Experimental Biology and Medicine, SWOG

Disclosure: Partner received none from No financial interests for none.

Chief Editor

Emmanuel C Besa, MD Professor Emeritus, Department of Medicine, Division of Hematologic Malignancies and Hematopoietic Stem Cell Transplantation, Kimmel Cancer Center, Jefferson Medical College of Thomas Jefferson University

Emmanuel C Besa, MD is a member of the following medical societies: American Association for Cancer Education, American Society of Clinical Oncology, American College of Clinical Pharmacology, American Federation for Medical Research, American Society of Hematology, New York Academy of Sciences

Disclosure: Nothing to disclose.


Wadie F Bahou, MD Chief, Division of Hematology, Hematology/Oncology Fellowship Director, Professor, Department of Internal Medicine, State University of New York at Stony Brook

Wadie F Bahou, MD is a member of the following medical societies: American Society of Hematology

Disclosure: Nothing to disclose.

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Peripheral blood smear in essential thrombocytosis showing increased platelet numbers. Courtesy Wei Wang, MD, and John Lazarchick, MD; Department of Pathology, Medical University of South Carolina.
Bone marrow biopsy in essential thrombocytosis showing increased megakaryocytes. Courtesy Wei Wang, MD, and John Lazarchick, MD; Department of Pathology, Medical University of South Carolina.
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