Effect of impaired renal function on tamoxifen.

There is no information available in the literature on the blood levels of tamoxifen in patients with decreased renal function. As serious side effects of tamoxifen administered at high doses have been reported, a patient with decreased renal function and metastatic breast cancer was studied to determine the blood levels of tamoxifen while under therapy. Since no abnormally elevated levels of tamoxifen were found in this patient during the month of therapy, results of this study indicate that tamoxifen can be administered to patients with some degree of renal impairment without the risk of giving rise to abnormally elevated blood levels.