Well the issue in reality is that there was never a connection confirmed to M99 by the Miami Metro homicide dept to the victims of the BHB. New Blood made a huge mistake by allowing Angela to make a connection to Dexter and the BHB based on getting photos from the MMHD and having a picture of a victims severed head that had a circle around the "wheel mark on his neck that was proof of a drug in the victims system. That was never brought to light in the original.

Leon the Miami records should have never had a relation to either of the drugs because there was never a connection to M99 and the BHB in the original Dexter. So switching the drugs doesn't really matter unless you get technical about it by understanding that Ketamine wouldn't cause instant paralysis like M99 does. the use of Ketamine in New Blood was because Michael C. Halls band had a single released around the New Blood release and the song is called Ketamine

What they really need to do is explain how Angela searched "Ketamine and Homicides" and the first article was about the BHB. The search result was the ultimate reason for her then going into the Miami Metro database and getting BHB related photos. However these photos need an explanation as well because of two reasons. Who was the victim that's head was photographed and why was there a circle around a "wheel mark" on his neck? The fact that this related information was never brought to light in the original series makes her findings absurd. She should have been able to make a connection to Dexter being the BHB by what happened two the two guys in New Blood that he injected one and attempted the other. That to me was a huge blunder in New Blood

There is a huge difference when it comes to Angela searching "Ketamine" related murders in Miami and the first article was the Bay Harbor Buthcher which makes no sense at all. But realistically the search of either drugs shouldn't have given a related article because never did they confirm a pattern or connection to M99 and the victims. The only time was when Masuka ran a drug on the wife of the husband who was the Coyote or the Cuban people smuggler and Dexter covered it up never to be referred to again in the series.