I will probably use a template I already have for this issue
Really basic actually, it divides the medication in specific categories:
Morning , Afternoon , Night , before meals , after meals, etc...
This is basically to show the patient when and how many pills to take at a given time. It serves to simplify his prescription.
From Karsten's PDF I would advocate the use of separator lines between the fields to improve readability even more so for the visually challenged.
The regimen field I guess is the part where people will have the worst use for, everywhere it is used differently, so I sugest making some 3 or 4 templates as "default GNUmed" with these modifications in mind (if that is remotely possible ;) like hours to take the meds (at 8h or at hours 8-16-24) , hours separating each dose (Amoxicilin 8/8h or every 8h) ... of will the client ask us how we want it displayed?