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Leukemoid Reactions And The Pharmacology Of Drugs Used For The Treatment Of Acute Leukemias
A General Overview
Leukemoid reaction is a non-neoplastic reactive leucocytosis characterized by the presence of immature cells of all stages in peripheral blood. This may involve the myeloid, lymphatic or other cell types. Children are affected more frequently than adults.
- Acute infections like pneumonia, septicemia, whooping cough, chicken pox, infectious mononucleosis, diphtheria and meningitis
- Chronic infections like tuberculosis and amoebic live abscess.
- Hemolytic crises and massive hemorrhages
- Metastatic carcinoma involving the bone marrow especially from neuroblastoma, lungs etc
- Other hematological malignancies, eg, multiple myeloma, myelofibrosis and Hidgkin’s disease
- Toxic states like eclampsia, burns and mercury poisoning.
The blood picture is myeloid in pneumonia, meningitis, diphtheria, tuberculosis, amoebic live abscess, metastatic malignancies, multiple myeloma, post hemorrhagic states and hemolysis. Lymphoid picture occurs in whooping cough, chicken pox, infectious mononucleosis and tuberculosis. Monocytic reaction rarely occurs in disseminated tuberculosis. Eosinophilic picture occurs in amoebiasis, melanomatosis and invasive stages of helminthiasis. The bone marrow is normal with accelerated leukopoiesis in leukemoid reaction unlike as in leukemia. Total leucocytes counts may vary widely and overlap with those of leukemia. Liver and spleen are not usually enlarged. Leucocyte alkaline phosphatase is increased in leukemoid reaction whereas it is low in chronic myeloid leukemias. Treatment of the underlying disorder corrects the blood picture also.
Mechanisms Of Action And Toxic Side Effects Of Drugs
Mechanism of action
Adverse side effect
1. Vincristine (Oncovin)
Alopecia, leucopenia, peripheral neuropathy and myelopathy
2. Doxorubicin, Rubidazone, Hydroxydoxorubicin (Adriamycin)
Binds DNA and inhibits mitosis
Alopecia, leucopenia and myocarditis
Deprives the cells of asparagine
Hypersensitivity, hepatic dysfunction, pancreatitis
4. 6-Mercaptopurine, 6-Thioguanine, Cytosine arabinoside, Methotrexate
Inhibit purine or pyrimidine synthesis or inhibit incorporation into DNA
Ulceration of mouth and GI tract, leukopenia
Alkylating agent, cross-links DNA and impairs RNA formation
Alopecia, leucopenia, marrow aplasia, pigmentation, hemorrhagic cystitis, pulmonary fibrosis
Mechanism of action is not clear
Several toxic effects.
Drugs are usually given in combination cyclically or as continuous dosage. The selection, dose and sequence of administration of these drugs depend on the type of leukemia. The dosage is usually calculated in terms of body surface area (which can be read off from nomograms- using the height and weight) and this is more reliable than determining the dose on the basis of body weight. Combination of different drugs and intermittent administration has served to reduce the dosage and toxicity of each drug, and improve the effectiveness by optimal action at the appropriate phases of the cell cycle.
© 2014 Funom Theophilus Makama