Erlotinib
Erlotinib. EGFR tyrosine kinase inhibitor — competitive ATP-site blockade. First-line therapy for EGFR-mutant non-small-cell lung cancer. CYP3A4… Oral half-life 36 h.
EGFR tyrosine kinase inhibitor — competitive ATP-site blockade. First-line therapy for EGFR-mutant non-small-cell lung cancer. CYP3A4 substrate. Acneiform rash (~75%) correlates with response. Smoking induces CYP1A2-mediated clearance, lowering levels.
PK: ITS CITATION WAS A RIFAMPICIN INTERACTION STUDY REPORTING ONLY EXPOSURE RATIOS — none of the four stored values. A population fit of 4068 samples from 1047 patients, using "a 1-compartment model with first-order absorption" — this registry exact model shape — supplies three verbatim: "the oral clearance was 3.95 L/h, the oral volume of distribution was 233 L, and the absorption rate was 0.95 h(-1). The median erlotinib half-life ... was 36.2 hours". THE THIRD SURVIVING ka OF THE BATCH, AND IT REFUTES THE STORED ONE: 0.95 is nearly double 0.5, and it independently checks out, reproducing a 4.2 h peak against this drug observed 4 h while 0.5 gives 6.8 h. CLASS 6 IS CONFIRMED HERE FROM THE PAPER OWN WORDS rather than from record shape: it NAMES its 233 L the "oral volume of distribution", and the only intravenous erlotinib study publishes no volume at all — so F is pinned to 1. The measured absolute bioavailability is 59% with a 55-63% interval, and a competing 76% median in patients is recorded rather than silently dropped. Exposure also moves with smoking, food and gastric pH.
Pharmacokinetics
- Oral — t½ 36.2 h · F 100% · ka 0.95 h⁻¹ · Vd 233 L
Sources: PMID:9354447, PMID:16890575, PMID:16490804, PMID:18176118