Applicant/PHRC: Hetero Drugs South Africa (Pty) Ltd
Product proprietary name: ELODYST
Dosage form and strength: Powder for concentrate for Solution for infusion and 50 mg/vial
t1/2 = terminal elimination half life
Vdss = mean volume of distribution at steady state
Decitabine exhibits linear PK and following the intravenous infusion, steady-state concentrations are
reached within 0,5 hour. Based on model simulation, PK parameters were independent of time (i.e., did not
change from cycle to cycle) and no accumulation was observed with this dosing regimen. Plasma protein
binding of decitabine is negligible (< 1 %). Decitabine Vdss in cancer patients is large indicating distribution
of the medicine into peripheral tissues.
There was no evidence of dependencies on age, creatinine clearance, total bilirubin, or disease.
Biotransformation
Intracellularly, decitabine is activated through sequential phosphorylation via phosphokinase activities to the
corresponding triphosphate, which is then incorporated by the DNA polymerase.
In light of in vitro metabolism data, the human mass balance study results indicated that the cytochrome
P450 system is not involved in the metabolism of decitabine. The primary route of metabolism is likely
through deamination by cytidine deaminase in the liver, kidney, intestinal epithelium, and blood.
Results from the human mass-balance study showed that unchanged decitabine in plasma accounted for
approximately 2,4 % of total radioactivity in plasma.
The major circulating metabolites are not believed to be pharmacologically active. The presence of these
metabolites in urine together with the high total body clearance and low urinary excretion of unchanged
medicine in the urine (~4 % of the dose) indicate that decitabine is appreciably metabolised in vivo. In
addition, in vitro data show that decitabine is a poor P-gp substrate.
Elimination
Mean plasma clearance following intravenous administration in cancer subjects was > 200 L/h with
moderate inter-subject variability (Coefficient of Variation [CV] is approximately 50 %). Excretion of
unchanged medicine appears to play only a minor role in the elimination of decitabine. Results from a mass
balance study with radioactive 14C-decitabine in cancer patients showed that 90 % of the administered
dose of decitabine (4 % unchanged medicine) is excreted in the urine.
Initial M.U
05 September 2023
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