I'm pretty sure it would be simply L-Carnitine or Carnitine. Supposing there are multiple forms of Carnitine available by prescription there are various forms of Carnitine available.
L-Carnitine-L-Tartrate is a pretty common on, usually under the registered name CarniPure
Glycine Propionyl-L-Carnitine is a newer one that is increasing in popularity in bodybuilding supplements, usually under the registered name GPLC
Acetyl-L-carnitine is another common and popular form of carnitine. Typically taken for memory support due to it's ability to cross the blood/brain barrier.
Is it worth it? Pending the cost, I would say yes.