Disclosed are methods for treating Alzheimer's disease, and other diseases, and/or inhibiting beta-secretase enzyme, and/or inhibiting deposition of A beta peptide in a mammal, by use of hydrazine compounds of formula (I) wherein the variables R
1
-R
9
are defined herein.
Disclosed are compounds of formula (I) and pharmaceutically acceptable salts and esters thereof, useful in treating and/or preventing Alzheimer's disease and other similar diseases, wherein RN, RC, R1, R2 and R20 are defined herein. These compounds include inhibitors of the beta-secretase enzyme that are useful in the treatment of Alzheimer's disease and other diseases characterized by deposition of A beta peptide in a mammal. The compounds of the invention are useful in pharmaceutical compositions and methods of treatment to reduce A beta peptide formation.