1. Clinical Overview
Levo-carnitine (L-carnitine) is a naturally occurring amino acid derivative that is essential for the transport of long-chain fatty acids into the mitochondrial matrix for beta-oxidation and energy production. The 'NA' designation typically refers to its formulation as a nutritional supplement or as a prescription drug for specific deficiencies. In the Indian market, it is used both as a prescription medicine for primary and secondary carnitine deficiencies and as a widely available over-the-counter supplement for various conditions.
| Onset | Duration | Bioavailability |
|---|---|---|
| Oral: 2-4 hours for measurable metabolic effects; Intravenous: Within 1-2 hours. | Approximately 6-12 hours, depending on dose and route of administration. | Oral: 5-18% (due to extensive first-pass metabolism and active transport saturation). |
2. Mechanism of Action
L-carnitine is a cofactor required for the transport of activated long-chain fatty acids (acyl-CoA esters) from the cytosol into the mitochondrial matrix. This transport is mediated by the carnitine palmitoyltransferase (CPT) system (CPT I and CPT II) and the carnitine-acylcarnitine translocase. Inside the mitochondria, fatty acids undergo beta-oxidation to produce acetyl-CoA, which enters the Krebs cycle for ATP generation.
3. Indications & Uses
- Primary systemic carnitine deficiency (SCD)
- Secondary carnitine deficiency in hemodialysis patients
- Carnitine deficiency due to inborn errors of metabolism (e.g., organic acidurias, mitochondrial disorders)
4. Dosage & Administration
Adult Dosage: Deficiency States: Oral: 990 mg to 2,970 mg per day in 2-3 divided doses. IV: 50 mg/kg as a bolus or infusion, up to a maximum of 3 g per dose. Hemodialysis: IV: 20 mg/kg post-dialysis (typically 1-3 g).
Administration: Oral: Take with meals to reduce GI upset. Tablets/Capsules should be swallowed whole. Liquid formulations can be taken directly or mixed with drinks. IV: Must be diluted and administered as a slow infusion over 2-3 minutes or as a 2-3 hour infusion for larger doses. Never administer as a rapid IV bolus.
5. Side Effects
Common side effects may include:
- Nausea
- Vomiting
- Abdominal cramps
- Diarrhea
- Body odor (fishy or ammonia-like)
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Valproic Acid / Valproate | Valproate depletes carnitine levels. Concurrent use may require higher L-carnitine doses to prevent deficiency. | Major |
| Warfarin | Theoretical interaction; L-carnitine may potentiate anticoagulant effect. Monitor INR closely. | Moderate |
| Thyroid Hormones (Levothyroxine) | L-carnitine may inhibit peripheral action of thyroid hormone. Monitor thyroid function. | Moderate |
| Acitretin, Isotretinoin | May increase risk of myalgia and elevated CPK. Monitor. | Moderate |
| Zidovudine (AZT) | L-carnitine may reduce AZT-induced myopathy. | Minor (Beneficial) |
7. Patient Counselling
- Do take with food to minimize stomach upset.
- Do inform your doctor if you are on dialysis or have kidney problems.
- Do report any fishy body odor to your doctor.
- Don't take double doses to make up for a missed dose.
- Don't stop taking suddenly if prescribed for a metabolic disorder.
8. Toxicology & Storage
Overdose: Diarrhea, abdominal cramps, nausea, vomiting, body odor. Severe overdose (very rare) may cause myasthenia-like syndrome (muscle weakness), seizures, or uremic odor in dialysis patients.
Storage: Store at room temperature (15-30°C), protected from light and moisture. Keep oral solutions tightly closed. Do not freeze. Keep out of reach of children. For IV solutions, use immediately after dilution; discard any unused portion.