Assessing the In Vitro and In Vivo Performance of L Carnitine Loaded Nanoparticles in Combating Obesity Acetyl L Carnitine vs L Carnitine: 4 Key Differences Momentous L Carnitine is often marketed as a fat burner, but most people dont realize that oral and injectable L Carnitine are not the same..Oral L Carnitine has poor absorption (only 20% bioavailability), L Carnitine injection is recommended at 1 ampule every 2 3 days for best results. The L Carnitine is taken intravenously either by normal injection or using a butterfly needle. After taking this L Carnitine, you