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Bone Effects: Osteoporosis and/or bone fractures have been reported with the use of Femara. Therefore, monitoring of overall bone health is recommended during treatment (see ADVERSE REACTIONS and PHARMACOLOGY: PHARMACODYNAMICS under ACTIONS).
Menopausal status: In patients whose menopausal status is unclear, luteinising hormone (LH), follicle-stimulating hormone (FSH) and/or estradiol levels should be measured before initiating treatment with Femara. Only women of confirmed postmenopausal endocrine status should receive Femara.
Fertility: The pharmacological action of letrozole is to reduce estrogen production by aromatase inhibition. In premenopausal women, the inhibition of estrogen synthesis leads to feedback increases in gonadotropin (LH, FSH) levels. Increased FSH levels in turn stimulate follicular growth, and can induce ovulation.
Interactions: Co-administration of Femara with tamoxifen, other anti-estrogens or estrogen-containing therapies should be avoided as these substances may diminish the pharmacological action of letrozole. The mechanism of this interaction is unknown (see INTERACTIONS).
Driving and Using Machines: Since fatigue and dizziness have been observed with the use of Femara and somnolence has been reported uncommonly, caution is advised when driving or using machines.
Renal impairment: Femara has not been investigated in patients with creatinine clearance <10 mL/min. The potential risk/benefit to such patients should be carefully considered before administration of Femara.
Hepatic impairment: In patients with severe hepatic impairment (Child-Pugh score C), systemic exposure and terminal half-life were approximately doubled compared to healthy volunteers. Such patients should therefore be kept under close supervision (see PHARMACOLOGY: PHARMACOKINETICS under ACTIONS).
