Enhanced Bioavailability of L Carnitine After Painless Intradermal Delivery vs. Oral Administration in Rats Pharmaceutical Research Springer Nature Link L Carnitine Linus Pauling Institute Oregon State University Injectable carnitine vs oral version comparison? Assessing the In Vitro and In Vivo Performance of L Carnitine Loaded Nanoparticles in Combating Obesity 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),