Optimizing tamoxifen therapy through the induction of CYP3A4, CYP2C and CYP2D6 mediated metabolism - Induction of tamoxifen metabolism

Status

Not yet recruiting

Phases

Unknown

Study type

Interventional

Source

EU CTR

Registry ID

EUCTR2010-023776-52-NL

Enrollment

Registered

2010-11-24

Start date

2011-01-19

Completion date

Unknown

Last updated

2012-03-19

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Breast cancer MedDRA version: 12.1 Level: LLT Classification code 10006187 Term: Breast cancer

Interventions

Trade Name: Nolvadex Product Name: Tamoxifen Pharmaceutical Form: Tablet INN or Proposed INN: TAMOXIFEN CAS Number: 10540-29-1 Concentration unit: mg milligram(s) Concentration type: range Concentrati

Eligibility

Sex/Gender

All

Inclusion criteria

Inclusion criteria: • Histological or cytological confirmed diagnosis of (invasive) breast cancer, for which treatment with tamoxifen monotherapy is indicated (to be evaluated by the treating physician); • Use of tamoxifen monotherapy for at least 4 weeks (to guarantee steady-state) and willing to continue the treatment until the second day of pharmacokinetic analyses; Are the trial subjects under 18? no Number of subjects for this age range: F.1.2 Adults (18-64 years) yes F.1.2.1 Number of subjects for this age range F.1.3 Elderly (>=65 years) yes F.1.3.1 Number of subjects for this age range

Exclusion criteria

Exclusion criteria: • Pregnant or lactating patients; • Impossibility to take oral drugs; • Serious illness or medical unstable condition requiring treatment, symptomatic CNS-metastases or history of psychiatric disorder that would prohibit the understanding and giving of informed consent; • Contra-indications for rifampicin and/or dextromethorphan use; • Use of medications or dietary supplements known to induce or inhibit CYP2D6, CYP2C, CYP3A4 and/or P-glycoprotein; • Unwillingness to abstain from grapefruit (juice), (herbal) dietary supplements, herbals, over-the-counter medication (except for paracetamol and ibuprofen) and other drugs known to seriously interact with CYP3A during the study period; • Non-compliance

Design outcomes

Primary

Measure	Time frame
Main Objective: - To determine the influence of cytochrome P450 enzyme induction (including CYP3A4, CYP2C and CYP2D6) by rifampicin on the metabolism and plasma pharmacokinetics of tamoxifen and its metabolites in breast cancer patients. ;Secondary Objective: - To compare the incidence and severity of side effects of treatment with tamoxifen in the presence and absence of rifampicin. - To validate the previously developed dextromethorphan phenotyping test;Primary end point(s): This is a randomized crossover pharmacokinetic study intended to investigate the effect of cytochrome P450 enzyme induction (including CYP3A4, CYP2C and CYP2D6) by rifampicin on the metabolism and plasma pharmacokinetics of tamoxifen and its metabolites.	—

Measure

Time frame

Main Objective: - To determine the influence of cytochrome P450 enzyme induction (including CYP3A4, CYP2C and CYP2D6) by rifampicin on the metabolism and plasma pharmacokinetics of tamoxifen and its metabolites in breast cancer patients. ;Secondary Objective: - To compare the incidence and severity of side effects of treatment with tamoxifen in the presence and absence of rifampicin. - To validate the previously developed dextromethorphan phenotyping test;Primary end point(s): This is a randomized crossover pharmacokinetic study intended to investigate the effect of cytochrome P450 enzyme induction (including CYP3A4, CYP2C and CYP2D6) by rifampicin on the metabolism and plasma pharmacokinetics of tamoxifen and its metabolites.

—

Countries

Netherlands

Outcome results

None listed

Source: EU CTR (via WHO ICTRP) · Data processed: Feb 4, 2026