Regarding drug product degradation, can acid or base hydrolysis occur in non-aqueous liquid formulations? If no, should I perform acid/base hydrolysis in forced degradation study of such formulations?
Yes you need to do so. On stability there is always water involved, Also you need to know all the potential degradation products involving acid, base, peroxides, heat, light, etc.
Hydrolysis will not occur, if your reaction doesn't have water at all. On the other hand, setting truly dry conditions is very difficult. You should remove a slight amount of water from your substrates, flasks, and the atmosphere. (It is impossible to remove the moisture in the air, unless the air is exchanged to pure nitrogen or argon.
In addition, you should consider about the alcoholysis or aminolysis, when you use alcohols or amines as solvents.