Xenazole Adverse Reactions

Summary of the safety profile: Letrozole was generally well tolerated across all studies as first-line and second-line treatment for advanced breast cancer, as adjuvant treatment of early breast cancer and as extended adjuvant treatment in women who have received prior standard adjuvant therapy with tamoxifen. Approximately one third of the patients treated with letrozole in the metastatic and neoadjuvant settings, approximately 81% of the patients in the adjuvant setting (in both letrozole and tamoxifen arms), 87-88% of the patients in the sequential treatment arms, at a median treatment duration of 60 months, and approximately 80% of the patients in the extended adjuvant setting (both letrozole and placebo arms at a median treatment duration of 60 months) experienced adverse reactions. Generally, the observed adverse reactions are mild or moderate in nature, and many are associated with estrogen deprivation.
The most frequently reported adverse reactions in the clinical studies were hot flushes, arthralgia, nausea and fatigue. Many adverse reactions can be attributed to the normal pharmacological consequences of estrogen deprivation (e.g. hot flushes, alopecia and vaginal bleeding). The following adverse drug reactions, listed in Table 9, were reported from clinical studies and from post marketing experience with letrozole.
Tabulated summary of adverse drug reactions from clinical trials and from post marketing experience with letrozole: Adverse reactions are ranked under headings of frequency, the most frequent first, using the following convention: Very common (≥10%); Common (≥1%, to <10%); Uncommon (≥0.1%, to <1%); Rare (≥0.01%, <0.1%); Very rare (<0.01%) and Not known (cannot be estimated from the available data). (See Table 9.)

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Description of selected adverse drug reactions: Cardiac adverse reactions: In the adjuvant setting, in addition to the data presented in Table 5, the following adverse events were reported for letrozole and tamoxifen, respectively (median treatment duration of 5 years): angina requiring surgery (1.0% vs. 1.0%); cardiac failure (1.1% vs. 0.6%); hypertension (5.6% vs. 5.7%); cerebrovascular accident/transient ischaemic attack (2.1% vs. 1.9%).
In the extended adjuvant setting for letrozole (median duration of treatment 5 years) and placebo (median duration of treatment 3 years), respectively: angina requiring surgery (0.8% vs. 0.6%); new or worsening angina (1.4% vs. 1.0%); myocardial infarction (1.0% vs. 0.7%); thromboembolic event* (0.9% vs. 0.3%); stroke/transient ischaemic attack* (1.5% vs. 0.8%) were reported.
Events marked * were statistically significantly different in the two treatment arms.
Skeletal adverse reactions: For skeletal safety data from the adjuvant setting, please refer to Table 5.
In the extended adjuvant setting, significantly more patients treated with letrozole experienced bone fractures or osteoporosis (bone fractures, 10.4% and osteoporosis, 12.2%) than patients in the placebo arm (5.8% and 6.4%, respectively). Median duration of treatment was 5 years for letrozole, compared with 3 years for placebo.