Description
Generic
Letrozole
Indications
Letrozole is used to treat advanced/metastatic breast cancer in postmenopausal women who have hormone receptor-positive or unknown receptor status.
Pharmacology
Letrozole is a nonsteroidal aromatase inhibitor that is both potent and highly specific. It inhibits the aromatase enzyme by binding competitively to the haem of the cytochrome P450 subunit, resulting in a decrease in estrogen biosynthesis in all tissues. Letrozole works as an antitumor agent by preventing estrogen-dependent breast cancer cells from growing.
Dosage & Administration
Letrozole is taken once a day at a dose of 2.5 mg. Letrozole treatment should be continued as long as the tumor responds. If the tumor stops responding, as determined by tumor progression, the drug should be stopped. The normal adult dosage regimen does not need to be changed for elderly patients. Patients with mild to moderate hepatic impairment do not need to adjust their dosage.
Interaction
Even though cimetidine is a known inhibitor of one of the cytochrome P450 isoenzymes capable of metabolizing letrozole in vitro, clinical interaction studies with these drugs revealed that co-administration of letrozole with these drugs does not result in clinically significant drug reactions.
Contraindications
If you have a known or suspected hypersensitivity to letrozole, other aromatase inhibitors, or any of their ingredients, don’t take it. It’s not recommended for use during pregnancy, lactation, or in premenopausal women. It’s also not recommended if you have severe hepatic dysfunction.
Side Effects
Letrozole side effects are usually mild to moderate, and only rarely severe enough to require discontinuation. Many can be attributed to the underlying disease or the normal pharmacological effect of oestrogen deficiency (hot flushes, hair thinning).
Pregnancy & Lactation
At 0.03 mg/kg, teratogenicity and maternal toxicity were observed in pregnant rats after oral administration of letrozole. At doses greater than 0.003 mg/kg, embryotoxicity and foetotoxicity were observed, as well as an increase in the incidence of foetal malformation in the animals. However, letrozole has not been studied adequately or thoroughly in pregnant women, and its use in these patients is not recommended.
Precautions & Warnings
There is no need to adjust the dosage in breast cancer patients with moderate hepatic dysfunction, but caution is advised because letrozole elimination is primarily dependent on intrinsic metabolic clearance. At doses of 2.5 mg and 5 mg, renal impairment (calculated creatinine clearance: 20 to 50 ml/min) had no effect on steady-state plasma letrozole concentration.
Therapeutic Class
Hormonal Chemotherapy is a type of chemotherapy that uses hormones to kill cancer cells
Storage Conditions
Keep the temperature below 30°C and away from light and moisture. Keep out of children’s reach.
