Neoethylene

Neoethylene was a type of drug compound used in 23rd century Federation medicine.

When the USS Enterprise (NCC-1701) was overrun with appeared to be "giant tribbles" in 2269, Doctor Leonard McCoy was able to remedy the situation by giving them "a simple shot" of neoethylene. As a result, the "giant tribbles", which were in reality tribble colonies with voracious appetites, broke down into their individual units with a slower metabolic rate. 

Neoacillin