Genzifen Special Precautions

Menstruation is suppressed in a proportion of premenopausal women receiving Tamoxifen (Genzifen) for the treatment of breast cancer.
An increased incidence of endometrial cancer and uterine sarcoma (mostly malignant mixed Mullerian tumors) has been reported in association with Tamoxifen (Genzifen) treatment. The underlying mechanism is unknown, but may be related to the estrogen-like effect of Tamoxifen (Genzifen). Any patients receiving or having previously received Tamoxifen (Genzifen), who report abnormal gynaecological symptoms, especially vaginal bleeding, should be promptly investigated.
Nonetheless, the possibility that Tamoxifen (Genzifen) may affect the development of endometrial pathology, including neoplasia, should be kept in mind when designing treatment regimens.
Investigations in different in vivo and in vitro systems have shown that Tamoxifen (Genzifen) has a genotoxic potential following hepatic activation. Gonadal tumors in mice and liver tumors in rats receiving Tamoxifen (Genzifen) have been reported in long-term studies. The clinical relevance of these findings has not been established.
A number of second primary tumours, occurring at sites other than the endometrium and the opposite breast, have been reported in clinical trials, following the treatment of breast cancer patients with Tamoxifen (Genzifen). No causal link has been established and the clinical significance of these observations remains unclear.
In delayed microsurgical breast reconstruction, Tamoxifen (Genzifen) may increase the risk of microvascular flap complications. In an uncontrolled trial in 28 girls aged 2-10 years with McCune Albright Syndrome (MAS), who received 20 mg once a day for up to 12 months duration, mean uterine volume increased after 6 months of treatment and doubled at the end of the one-year study. While this finding is in line with the pharmacodynamic properties of Tamoxifen (Genzifen), a causal relationship has not been established.
Tamoxifen (Genzifen) contains lactose. Patients with rare hereditary problems of galactose intolerance, the Lapp lactase deficiency or glucose-galactose malabsorption should not take this medicine.
In the literature it has been shown that CYP2D6 poor metabolisers have a lowered plasma level of endoxifen, one of the most important active metabolites of Tamoxifen (Genzifen).
Concomitant medications that inhibit CYP2D6 may lead to reduced concentrations of the active metabolite endoxifen. Therefore, potent inhibitors of CYP2D6 (e.g. paroxetine, fluoxetine, quinidine, cinacalcet or bupropion) should whenever possible be avoided during Tamoxifen (Genzifen) treatment.
Effects on ability to drive and use machines: Tamoxifen (Genzifen) is unlikely to impair the ability of patients to drive or use machinery. However, fatigue has been reported with the use of Tamoxifen (Genzifen) and caution should be observed when driving or using machinery while such symptoms persist.