Head to a camera shop and ask for a lens cleaner solution for coated lenses.
They will probably sell you something containing Isobutlyl alcohol, or more commonly known as rubbing alcohol. It can be supplied coloured for safety or clear. (the clear is normally more expensive and concentrated but either is good, whilst they have a laugh at all the people who by "specialist glass cleaners for screens".
In the States it's known as Formula 23-H as classified by the US Treasury department, Bureau of Alcohol Tobacco and Firearms.
As for worrying about the coating on the glass, They naturally wear off over time anyway and in fairness are not that far removed from rain repellent coatings for glass windscreens.