Pharmacokinetics and safety of neratinib during co-administration with loperamide in healthy subjects

Purpose To evaluate the effects of multiple doses of loperamide on the pharmacokinetics and safety of a single oral dose of neratinib. Methods This was an open-label, two-period, fixed-sequence study. Twenty healthy adult subjects received an oral dose of neratinib 240 mg daily on Days 1–4 of Period 1 followed by a 7-day washout. In Period 2, oral neratinib 240 mg was administered with loperamide 4 mg followed by two further doses of loperamide 2 mg 8 and 16 h later on Days 1–4. Pharmacokinetic sampling was performed for 72 h following each neratinib dose. Safety was monitored throughout the study. Results A median t max of ~ 6 h was observed for neratinib during both periods. Apparent clearance and volume of distribution were similar for Periods 1 and 2: mean CL ss / F 308.2 and 322.1 L/h; mean V zτ / F 7995 and 10,318 L, respectively. The half-life of neratinib increased in the presence of loperamide from 18.0 to 22.2 h. Mean exposure was within the same range without and with loperamide administration: C max 61.2 ng/mL and 49.5 ng/mL; AUC last 1086 ng h/mL and 1153 ng h/mL, and AUC tau 779 ng h/mL and 745 ng h/mL, respectively. Treatment-emergent adverse events were mainly mild in intensity, with the most frequent events being diarrhea (45%) and constipation (35%). Conclusions Neratinib administered alone and concomitantly with multiple oral doses of loperamide is generally safe and well tolerated. Loperamide has minimal effects on neratinib pharmacokinetic parameters.