Injectable L-Carnitine is a naturally occurring amino acid derivative (MW ~161.2 g/mol) that facilitates the transport of long-chain fatty acids across the mitochondrial inner membrane for beta-oxidation. While oral L-carnitine has poor bioavailability (5-18%), subcutaneous injection achieves near-100% bioavailability, making it a significantly more effective delivery method. It is FDA-approved in IV form (Carnitor) for primary carnitine deficiency and dialysis patients. SC injectable use for fat oxidation enhancement is off-label but widely used in metabolic optimization clinics.
Category: Metabolic / Fat Oxidation. Evidence rating: B (meaningful human data).
Clinical status: FDA-approved (IV, for carnitine deficiency). SC injection widely used off-label for metabolic optimization.
L-Carnitine binds long-chain fatty acyl-CoA molecules and shuttles them across the mitochondrial inner membrane via the carnitine palmitoyltransferase (CPT) system. CPT-I on the outer membrane converts fatty acyl-CoA to acylcarnitine; the carnitine-acylcarnitine translocase moves it across; CPT-II…
Safety considerations: Generally well tolerated; long safety record in approved IV formulations; SC injection site pain/burning (common with higher concentrations); Rare: nausea, diarrhea, body odor (fishy smell at very high doses).
Reviewed by the PeptideAtlas Editorial Team.
| Molecular formula | C7H15NO3 |
|---|---|
| Molecular weight | ~161.2 g/mol |
| CAS number | 541-15-1 |
| Half-life | ~2-4 hours (plasma) |
| Bioavailability | ~100% SC/IM; 5-18% oral |
| Production method | synthetic |
| Anti-doping status | not-listed |
| US regulatory status | FDA-approved as Carnitor (IV/oral) for primary carnitine deficiency and ESRD dialysis. SC injectable available from compounding pharmacies. |
Oral L-carnitine has only 5-18% bioavailability, and gut bacteria convert much of it to TMAO (a potential cardiovascular risk factor). SC injection achieves ~100% bioavailability, avoids TMAO production, and reliably increases muscle carnitine stores.
L-Carnitine facilitates fat transport into mitochondria but does not directly cause fat loss. It enhances the body ability to USE fat as fuel, particularly during exercise. Without a caloric deficit and physical activity, carnitine alone will not produce significant fat loss.
Injectable L-Carnitine is a naturally occurring amino acid derivative (MW ~161.2 g/mol) that facilitates the transport of long-chain fatty acids across the mitochondrial inner membrane for beta-oxidation. While oral L-carnitine has poor bioavailability (5-18%), subcutaneous injection achieves near-100% bioavailability, making it a significantly more effective delivery method. It is FDA-approved…
On the PeptideAtlas A–F scale, L-Carnitine (Injectable) is rated B (Moderate Evidence). Multiple human studies but not broadly approved for searched use
FDA-approved (IV, for carnitine deficiency). SC injection widely used off-label for metabolic optimization.