MPPP mentioned here is a street name for 4-Methyl-alpha-pyrrolidinopropiophenone: MEPPP. It's a synthetic Cathinone. There is also an unrelated synthetic heroin with a street name MPPP.

4-Methyl-alpha-pyrrolidinopropiophenone is a stimulant drug and substituted cathinone. 4-MePPP was sold in Germany as a designer drug in the late 1990s and early 2000s along with a number of other pyrrolidinophenone derivatives. Although it has never achieved the same international popularity as its better-known relations alpha-PPP and MDPV, 4-MePPP is still sometimes found as an ingredient of grey-market "bath salt" blends such as "NRG-3".

4'-Methyl-α-pyrrolidinopropiophenone Experiences:

• Cat tried some MPPP. He is 5"8' and 180 and insufflated between 150-200 mg to start. Immediately he jerked back in pain because it tends to burn your nose quite a lot if you're not used to it. That started to wear off as soon as Cat blew his nose. Within 5 min Cat was wide awake and talking much faster, with increased energy. In 30 min Cat started to become easily bored with things and started randomly cleaning around the house. This amused and entertained Cat. At the 3 hour mark, Cat started to feel less driven to do things and sat down to watch tv and play xbox. Total effects began to wear off at 6 hours although sleep would not come until 12+ hours. Even then sleep was fitful at best. No desire to eat until the next day.
  • SWIM experimented with this chemical some, probably snorting doses of around 100-200mg. Makes you more alert, but doesn't really produce any euphoria or give any worthwhile effects that would make SWIM want to do it again. Its somewhat comparable to a milder version of MDPV which requires a higher dose and is not as dose sensitive. SWIM never got an anxiety feeling like to much was taken
    • My reply is going to be similar to others. I received 5g's of 4'-Methyl-α-pyrrolidinopropiophenone a little more than a week ago, after sharing a small gram portion with an Elf I know, I had about 4grams left so i decided to load a small vial with approximately 1.5 grams and I carried it in my pocket all week and refilled it once. And I used a small amount each day. I was doing unknown amounts each time I was using a key to snort (bump) the material into my nostril. I noticed no ill / negative effects other than a sharp stinging which went away after the second of third day, and i also noticed one of the worst most disgusting drips down the back of the throat I have ever experienced. If one was going to try this material I would have to suggest having something sweet to drink other than water thats how bad the taste is. I am down to my last gram and have no urge to get anymore, why? Because the positive effects were as negligible as the negative effects. The very first time there was a "sense" of euphoria but it lasted only ten minutes. There was definitely an increase in energy similar to taking adderall(amphetamines) but it was short lived and repetitive snorting was necessary but not unlike cocaine in the sense that it was short lived. There was no hang over and no urge to do it. The only reason I did it everyday was because I had a lot of stuff to get done and it gave me just the right amount of energy I needed. This substance is not in any way comparable to methylone, MDPV or anything like that. Most people would consider this chemical a waste of time.

MPPP (4'-Methyl-α-pyrrolidinopropiophenone) Experiences Thread:
https://drugs-forum.com/threads/mppp-4-methyl-a-pyrrolidinopropiophenone-experience-reports.163241/

4-methyl-alpha-pyrrolidinopropiophenone Monograph (PDF 7 pages):
http://www.swgdrug.org/Monographs/4-methyl-alpha-pyrrolidinopropiophenone.pdf

4'-Methyl-.alpha.-pyrrolidinopropiophenone (hydrochloride) Safety Data Sheet (PDF 5 pages):
https://www.caymanchem.com/msdss/10446m.pdf