Effect of Ketoconazole Inhibition of CYP3A on Urinary Excretion of Docetaxel
Introduction: This is a follow-up protocol to an earlier study entitled "A phase I study of
docetaxel with ketoconazole modulation in solid tumors" (PH14/01) which showed 2-fold
reduction in docetaxel clearance and a clear correlation with renal function.
Aims: The aim of this study is to confirm that ketoconazole inhibition of CYP3A activity
changes the urinary excretion profile of docetaxel.
Methodology: This is a single-centre, crossover study. Ten patients (calculated sample size
=5, α=0.05, β=0.8, difference in means=5%, within group standard deviation=3) will be
accrued and randomly assigned to receive docetaxel at either 75mg/m2 q3w x 1 dose or 70mg
q3w x 1 dose with ketoconazole 200mg bid x q3d at cycle 1 of chemotherapy. This will be
followed by a 20-day washout period before receiving the other regimen of docetaxel at cycle
2. Blood samples of 5mls each will be drawn at times 0, 0.5h, 1h, 1.5h, 3h, 4h, 6h and 24h
after the onset of docetaxel infusion for pharmacokinetics analysis. A 24-hour urine
collection commencing on the same day as docetaxel infusion will be required of the
patients. All urine over the next 24 hours must be collected and returned to the study
coordinator on Day 2 of each study cycle for docetaxel analysis and creatinine clearance
determination. The amount of docetaxel excreted by each patient with and without
ketoconazole modulation will be determined by a LCMSMS method and compared.
Clinical Relevance: This is to ensure the safe advocation of a dose-sparing strategy
established in an earlier study for the costly agent docetaxel by confirming if changes in
excretion profile occurs once its major route of hepatic metabolism is blocked.
Allocation: Randomized, Endpoint Classification: Pharmacokinetics Study, Intervention Model: Crossover Assignment, Masking: Open Label, Primary Purpose: Treatment
To confirm if ketoconazole inhibition of CYP3A activity affects fractional excretion of docetaxel in the urine.
Boon Cher Goh, MBBS, MRCP
National University Hospital, Singapore
Singapore: Domain Specific Review Boards