L Carnitine Injections Nuceria Health, Miami, FL L Carnitine Oral Bioavailability NOW l Carnitine Supplement 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 Frontiers L carnitine prevents lenvatinib induced muscle toxicity without impairment of the anti angiogenic efficacy