The problem with propentofylline is that its oral bioavailability only 4%, so that means you have to start taking a lot of tablets to ensure you get a reasonable dose. A box of 60 x 100 mg tablets costs around $70. I was taking oral doses of around 5 to 10 of these tablets in one go.
Then I read here that propentofylline suppositories in coconut oil-based gels achieve 100% bioavailability, so I started experimenting with 200 to 300 mg of propentofylline in coconut oil and applied this sublingually and on the mucous membranes of my mouth; or at other times just on my skin transdermally.
The only side effect I had occurred when I took propentofylline with my morning coffee, and this made me feel very strange, as if not enough blood or oxygen was getting to my brain. So coffee and propentofylline are not a good combination. But apart from that, I had no side effects at all from propentofylline.
Note that propentofylline is not licensed for human use (it is a veterinary drug), but has been used in human trials for a number of health conditions.