I took it for four weeks and struggled immensely. It turned it out it was elevating my liver enzyme levels tremendously.
My suggestion if you start the drug: get weekly blood tests in the early days. My neurologist told me I could wait a month before getting a test. In retrospect, I should have listened to my body and had my blood checked earlier.
I’ve been off it now for three weeks and feel much better. Only taking mestinon and prednisone, and waiting for the effects of a thymectomy earlier this year to take hold.