LETROPUREN 2,5 mg Filmtabletten

Description

Pharmacokinetics

• Absorption

Letrozole is rapidly and completely absorbed from the gastrointestinal tract, with an average bioavailability of 99.9%. Ingestion of food slightly reduces the rate of absorption. The mean time to maximum plasma concentration (Tmah) of letrozole is 1 hour when taken on an empty stomach and 2 hours when taken with food; the mean maximum concentration (Cmah) is 129±20.3 nmol/l when taken on an empty stomach and 98.7±18.6 nmol/l when taken with food, but the absorption rate of letrozole (assessed by the area under the ‘concentration-time’ curve (AUC)) does not change. Small changes in the rate of absorption are not considered to be of clinical significance, and letrozole can therefore be taken independently of meals.

• Distribution

The binding of letrozole to plasma proteins is approximately 60% (mainly albumin – 55%). The concentration of letrozole in erythrocytes is approximately 80% of the plasma concentration. After administration of 2.5 mg of radioactively labelled letrozole, approximately 82% of the radioactivity in plasma remained unchanged, so systemic exposure of metabolites is very low.

Letrozole undergoes rapid and substantial distribution in tissues. The apparent volume of distribution at equilibrium is approximately 1.87±0.47 l/kg.