Disclosed are 2,2'-bipyridyl compounds, as well as pharmaceutical compositions and methods of use thereof. One embodiment is a compound having the structureand pharmaceutically acceptable salts, prodrugs and N-oxides thereof (and solvates and hydrates thereof), wherein R1, Z and n are as described herein. In certain embodiments, a compound disclosed herein inhibits GDF8, and can be used to treat disease by blocking GDF8 signaling.本發明揭示2,2'-聯吡啶基化合物以及其醫藥組合物及使用方法。一個實施例為具有以下結構之化合物及其醫藥學上可接受之鹽、前藥及N-氧化物(及其溶劑合物及水合物)，其中R1、Z及n如本文所描述。在某些實施例中，本文所揭示之化合物抑制GDF8，且可用於藉由阻斷GDF8信號傳導來治療疾病。
