Levocarnitine
Levocarnitine (L-carnitine) is a naturally occurring amino acid derivative synthesized in vivo from methionine and lysine, essential for normal fat utilization and energy metabolism. In veterinary medicine, it is primarily utilized as a nutraceutical adjunct for: * **Dilated Cardiomyopathy (DCM)** in dogs (especially American Cocker Spaniels and Boxers, where up to 90% may have a carnitine deficiency). * **Feline Hepatic Lipidosis**, where it facilitates hepatic lipid metabolism and clearance. * Protection against **doxorubicin-induced cardiomyopathy**. * Adjunctive treatment for **valproic acid toxicity**. **Clinical Pearl:** Only the L-isomer (levocarnitine) is biologically active and beneficial. Racemic mixtures containing D-carnitine must be avoided as they competitively inhibit L-carnitine uptake and can induce a deficiency.
Mechanism: Levocarnitine acts as an essential cofactor for the **carnitine palmitoyltransferase (CPT)** system. It binds to long-chain free fatty acids in the cytosol, forming acylcarnitine, which is then transported across the inner mitochondrial membrane. Inside the mitochondria โ the fatty acids undergo **beta-oxidation** โ generating **ATP** (cellular energy). This mechanism is particularly crucial for the myocardium, which relies heavily on fatty acid oxidation for energy, and for the liver during states of lipid mobilization (e.g., feline hepatic lipidosis).
Dosing by species
- Adjunctive dietary therapy in cats with severe hepatic lipidosis ยท 250 mg PO once daily ยท PO ยท q24h ยท Use Carnitor; also supplement with taurine (250 mg once to twice daily), Vitamin E (10 Units/kg/day), water soluble vitamins and determine B12 status (treat while awaiting data at 1 mg/cat SC).
- Supplementation in cats with liver disease ยท 250-500 mg/day ยท PO ยท q24h
- Trial for treating canine dilated cardiomyopathy (large or giant breed dog) ยท 2 grams PO q8-12h ยท PO ยท q8-12h ยท Approximately 1 teaspoonful of pure powder
- Adjunctive therapy of dilated cardiomyopathy in American Cocker spaniels ยท 1 gram PO q8-12h ยท PO ยท q8-12h ยท Give with taurine. Approximately 1/2 teaspoonful.
- Severe myocardial failure in Boxers ยท 2-3 grams PO q12h ยท PO ยท q12h ยท 2-4 months ยท To determine if they respond
- Adjunctive treatment of American cocker spaniels with dilated cardiomyopathy ยท 1 g PO q12h ยท PO ยท q12h ยท Give with taurine 500 mg q12h PO
- Dilated cardiomyopathy in American Cocker spaniels ยท 1 g PO q8h ยท PO ยท q8h
- Dilated cardiomyopathy in Boxer dogs ยท 2 g PO q8h ยท PO ยท q8h
- Documented systemic carnitine deficiency ยท 50-100 mg/kg PO q8h ยท PO ยท q8h
- Myocardial carnitine deficiency only ยท 200 mg/kg PO q8h ยท PO ยท q8h
Routes of administration
Contraindications
- Use of D-carnitine or racemic (D,L) mixtures (competitively inhibits L-carnitine uptake)
Adverse effects
- Gastrointestinal upset (loose stools, diarrhea, nausea, vomiting) - usually mild and dose-dependent
- Increased body odor (reported in human patients)
Drug interactions
- Valproic acid ยท Patients receiving valproic acid may require higher dosages of levocarnitine due to drug-induced carnitine depletion.
Monitoring
- Clinical efficacy (improvement in cardiac or hepatic signs)
- Periodic blood chemistries (recommended in humans, value in veterinary medicine is undetermined)
Overdose
Levocarnitine is a relatively safe drug. * **Minor overdoses**: Need only to be monitored. * **Massive overdoses**: Consider gut emptying (emesis or gastric lavage). Refer to a veterinary poison control center for more information.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturerโs current label.