COMMON BRAND NAME(S): Tykerb
GENERIC NAME(S): LAPATINIB DITOSYLATE
Description: Lapatinib is a 4-anilinoquinazoline tyrosine kinase inhibitor of both Epidermal Growth Factor Receptor (EGFR [ErbB1]) and Human Epidermal Receptor Type 2 (HER2 [ErbB2]) receptors. It blocks the phosphorylation and activation of downstream 2nd messengers (Erk1/2 and Akt) which regulate cellular proliferation and survival of ErbB- and ErbB2-expressing tumours.
Onset: 30 sec (IV); 3-4 min (IM).
Duration: 5-10 min (IV); 12-25 min (IM).
Absorption: Variable and incompletely absorbed. Systemic exposure is increased w/ food. Time to peak plasma concentration: Approx 4 hr.
Distribution: Plasma protein binding: >99% (albumin and α1 acid glycoprotein).
Metabolism: Undergoes extensive hepatic metabolism primarily via CYP3A4 and CYP3A5 isoenzymes, to a lesser extent via CYP2C19 and CYP2C8 isoenzymes.
Excretion: Via faeces approx 27% (parent lapatinib); approx 14% (metabolites). Terminal half-life: Approx 14 hr (single dose). Effective half-life: 24 hr (repeated dosing).