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Information |
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Drug Groups
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approved; investigational |
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Description
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A pyrimidine nucleoside analogue that inhibits DNA methyltransferase, impairing DNA methylation. It is also an antimetabolite of cytidine, incorporated primarily into RNA. Azacytidine has been used as an antineoplastic agent. [PubChem] |
| Indication |
For treatment of patients with the following French-American-British myelodysplastic syndrome subtypes: refractory anemia or refractory anemia with ringed sideroblasts (if accompanied by neutropenia or thrombocytopenia or requiring transfusions), refractory anemia with excess blasts, refractory anemia with excess blasts in transformation (now classified as acute myelogenous leukemia with multilineage dysplasia), and chronic myelomonocytic leukemia. |
| Pharmacology |
Azacitidine is believed to exert its antineoplastic effects by causing hypomethylation of DNA and direct cytotoxicity on abnormal hematopoietic cells in the bone marrow. The concentration of azacitidine required for maximum inhibition of DNA methylation in vitro does not cause major suppression of DNA synthesis. Hypomethylation may restore normal function to genes that are critical for differentiation and proliferation. The cytotoxic effects of azacitidine cause the death of rapidly dividing cells, including cancer cells that are no longer responsive to normal growth control mechanisms. Non-proliferating cells are relatively insensitive to azacitidine. Upon uptake into cells, azacitidine is phosphorylated to 5-azacytidine monophosphate by uridine-cytidine kinase, then to diphosphate by pyrimidine monophosphate kinases and triphosphate by diphosphate kinases. 5-Azacitidine triphosphate is incorporated into RNA, leading to the disruption of nuclear and cytoplasmic RNA metabolism and inhibition of protein synthesis. 5-Azacytidine diphosphate is reduced to 5-aza-deoxycytidine diphosphate by ribonucleotide reductase. The resultant metabolite is phosphorylated to 5-azadeoxycitidine triphosphate by nucleoside diphosphate kinases. 5-azadeoxycitidine triphosphate is then incoporated into DNA, leading to inhibition of DNA synthesis. Azacitidine is most toxic during the S-phase of the cell cycle. |
| Toxicity |
One case of overdose with azacitidine was reported during clinical trials. A patient experienced diarrhea, nausea, and vomiting after receiving a single IV dose of approximately 290 mg/m2, almost 4 times the recommended starting dose. |
| Affected Organisms |
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Humans and other mammals |
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| Biotransformation |
An in vitro study of azacitidine incubation in human liver fractions indicated that azacitidine may be metabolized by the liver. The potential of azacitidine to inhibit cytochrome P450 (CYP) enzymes is not known. |
| Absorption |
Azacitidine is rapidly absorbed after subcutaneous administration. The bioavailability of subcutaneous azacitidine relative to IV azacitidine is approximately 89%, based on area under the curve. |
| Half Life |
Mean elimination half-life is approximately 4 hours. |
| Elimination |
Following IV administration of radioactive azacitidine to 5 cancer patients, the cumulative urinary excretion was 85% of the radioactive dose.
Fecal excretion accounted for <1% of administered radioactivity over three days. Mean excretion of radioactivity in urine following SC administration of 14C-azacitidine was 50%. |
| Distribution |
* 76 ± 26 L |
| Clearance |
* 167 +/- 49 L/h |
| References |
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Cihak A: Biological effects of 5-azacytidine in eukaryotes. Oncology. 1974;30(5):405-22.
[Pubmed]
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Kaminskas E, Farrell AT, Wang YC, Sridhara R, Pazdur R: FDA drug approval summary: azacitidine (5-azacytidine, Vidaza) for injectable suspension. Oncologist. 2005 Mar;10(3):176-82.
[Pubmed]
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Leone G, Voso MT, Teofili L, Lubbert M: Inhibitors of DNA methylation in the treatment of hematological malignancies and MDS. Clin Immunol. 2003 Oct;109(1):89-102.
[Pubmed]
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Ghoshal K, Bai S: DNA methyltransferases as targets for cancer therapy. Drugs Today (Barc). 2007 Jun;43(6):395-422.
[Pubmed]
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Silverman LR, Demakos EP, Peterson BL, Kornblith AB, Holland JC, Odchimar-Reissig R, Stone RM, Nelson D, Powell BL, DeCastro CM, Ellerton J, Larson RA, Schiffer CA, Holland JF: Randomized controlled trial of azacitidine in patients with the myelodysplastic syndrome: a study of the cancer and leukemia group B. J Clin Oncol. 2002 May 15;20(10):2429-40.
[Pubmed]
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Silverman LR: Targeting hypomethylation of DNA to achieve cellular differentiation in myelodysplastic syndromes (MDS). Oncologist. 2001;6 Suppl 5:8-14.
[Pubmed]
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Issa JP, Kantarjian H: Azacitidine. Nat Rev Drug Discov. 2005 May;Suppl:S6-7.
[Pubmed]
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O'Dwyer K, Maslak P: Azacitidine and the beginnings of therapeutic epigenetic modulation. Expert Opin Pharmacother. 2008 Aug;9(11):1981-6.
[Pubmed]
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Siddiqui MA, Scott LJ: Azacitidine: in myelodysplastic syndromes. Drugs. 2005;65(13):1781-9; discussion 1790-1.
[Pubmed]
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Abdulhaq H, Rossetti JM: The role of azacitidine in the treatment of myelodysplastic syndromes. Expert Opin Investig Drugs. 2007 Dec;16(12):1967-75.
[Pubmed]
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Keating GM: Azacitidine: a review of its use in higher-risk myelodysplastic syndromes/acute myeloid leukaemia. Drugs. 2009;69(17):2501-18. doi: 10.2165/11202840-000000000-00000.
[Pubmed]
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Sullivan M, Hahn K, Kolesar JM: Azacitidine: a novel agent for myelodysplastic syndromes. Am J Health Syst Pharm. 2005 Aug 1;62(15):1567-73.
[Pubmed]
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Dapp MJ, Clouser CL, Patterson S, Mansky LM: 5-Azacytidine can induce lethal mutagenesis in human immunodeficiency virus type 1. J Virol. 2009 Nov;83(22):11950-8. Epub 2009 Sep 2.
[Pubmed]
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