Arimidex Adverse Reactions

Unless specified, the following frequency categories were calculated from the number of adverse events reported in a large phase III study conducted in 9366 postmenopausal women with operable breast cancer treated for 5 years (ATAC Study). (See Table 2.)

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The table as follows presents the frequency of pre-specified adverse events in the ATAC study, irrespective of causality, reported in patients receiving trial therapy and up to 14 days after cessation of trial therapy. (See Table 3.)

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The ATAC trial data showed that patients receiving ARIMIDEX had an increase in joint disorders (including arthritis, arthrosis, and arthralgia) compared with patients receiving tamoxifen. Patients receiving ARIMIDEX had an increase in the incidence of fractures (including fractures of spine, hip and wrist) compared with patients receiving tamoxifen. These differences were statistically significant. Fracture rates of 22 per 1000 patient-years and 15 per 1000 patient-years were observed for the ARIMIDEX and tamoxifen groups, respectively, after a median follow up of 68 months. The observed fracture rate for ARIMIDEX is similar to the range reported in age-matched postmenopausal populations. It has not been determined whether the rates of fracture and osteoporosis seen in ATAC in patients on anastrozole treatment reflect a protective effect of tamoxifen, a specific effect of anastrozole, or both.
The incidence of osteoporosis was 10.5% in patients treated with ARIMIDEX and 7.3% in patients treated with tamoxifen.
Patients receiving ARIMIDEX had a decrease in hot flushes, vaginal bleeding, vaginal discharge, endometrial cancer, venous thromboembolic events (including deep venous thrombosis) and ischaemic cerebrovascular events compared with patients receiving tamoxifen. These differences were statistically significant.
Results from the ATAC trial bone substudy, at 12 and 24 months demonstrated that patients receiving ARIMIDEX had a mean decrease in both lumbar spine and total hip bone mineral density (BMD) compared to baseline. Patients receiving tamoxifen had a mean increase in both lumbar spine and total hip BMD compared to baseline.
Slight increases in total cholesterol have also been observed in clinical trials with ARIMIDEX, although the clinical significance has not been determined.