The bioavailability of Tamoplex (tamoxifen). Part 3. A steady-state study in breast cancer patients.

The bioavailability of two tamoxifen preparations (Tamoplex and Nolvadex) was compared in a multiple dose two-way cross-over design in twelve breast cancer patients. The formulations were found to be bioequivalent. Mean steady-state serum levels of tamoxifen and N-desmethyltamoxifen were 133 ng/ml and 242 ng/ml, respectively, at a single daily dose of three tablets of Tamoplex 10 mg and 128 ng/ml and 248 ng/ml, respectively, at a single daily dose of three tablets of Nolvadex 10 mg. While there was a large interpatient as well as intrapatient variability in steady-state levels of tamoxifen and N-desmethyltamoxifen, their ratio appeared to be constant in the individual patient.