In fact, most Doctors have to re-adjust the dosage for their
elderly patients on medications because the
elderly respond differently to meds.
So I guess what I'm saying is that your "elderly friend" should contact her/his Doctor immediately and let her/his Doctor know of these "agitate/angry" responses to her/his meds.
Tarrie, since you came her on behalf of your elderly friend, maybe you can guide your friend in the process.