Injectable carnitine vs oral version comparison? Injectable vs Oral L Carnitine: Which Works Better? AWP 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 Enhanced Bioavailability of L Carnitine After Painless Intradermal Delivery vs. Oral Administration in Rats Pharmaceutical Research Springer Nature Link L Carnitine Injection Home Delivered 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),