ATAC - Pharmacokinetics (PK) Sub-Protocol

A Randomised, Double Blind Trial to Assess the Pharmacokinetics of Arimidex Alone, Nolvadex Alone, or Arimidex and Nolvadex in Combination, When Used as Adjuvant Treatment for Breast Cancer in Postmenopausal Women

To assess the effect of ARIMIDEX on the pharmacokinetics of tamoxifen and the effects of tamoxifen on the pharmacokinetics of ARIMIDEX..

Inclusion Criteria:

• Eligible for entry into the main ATAC trial 1033IL/0029
• Patients must have been taking ATAC trial medication for at least 3 months (i.e. patients must have reached at least visit 2 of the main ATAC study)
• Patients should be taking their medication in the mornings for at least 3 months
• Patients must be 100% compliant over the preceding fourteen days

Exclusion Criteria:

• Excluded from entry into the main ATAC trial (1033IL/0029)
• Patients whose concurrent treatment includes diazepam or drugs which might affect tamoxifen steady state levels or steroid hormone status. These include ketoconazole (antifungal) or related compounds