BACE1-IN-5 (Compound 15) is a β-site amyloid precursor protein cleaving enzyme 1 ( BACE1 ) inhibitor with an IC 50 of 9.1 nM, and also inhibits cellular amyloid-β (Aβ) with an IC 50 of 0.82 nM. BACE1-IN-5 has a medicinal chemistry that improves hERG inhibition and P-gp efflux.