“Gravel” is back in the news in another report out of Tennessee. Here is the article from WCYB.com
There is one error in the article. The drug that is thought to be in “gravel” is alpha-PVP, not alpha-PDD. I'm not even sure what alpha-PDD is, but I'm guessing it's just a typographical error.
But, with as quick as these drugs change and products evolve, I wouldn't be surprised if there was another drug or two (or ten) being used in "gravel" instead of alpha-PVP. In my own experience and in talking with other colleagues in the field, alpha-PVP is still widely available in the US, even after the enactment of various state laws and the placement of the compounds into Schedule I by the US federal government.