I believe prolintane was specifically developed to counter the sedative action of opioids.
Although related to pyrovalerone, it's a much milder stimulant. I believe it's still used medically for that purpose so I wouldn't be surprised to find it turning up on one of those dark markets.
I should add that I have never and will never use a dark market. People seem to forget that however secure an application is, it's only as secure as the OS it's running on. I would be EXTREMELY surprised if Telegram was truly secure, for example. In fact, I'm pretty sure that it has now been hacked.