レボカルニチン / L-カルニチン
レボカルニチン（L-カルニチン）は、メチオニンとリジンから生体内で合成される天然のアミノ酸誘導体であり、正常な脂肪利用とエネルギー代謝に不可欠です。 獣医学では、主に以下の補助療法として栄養補助食品として使用されます： * **犬の拡張型心筋症（DCM）**（特にコッカースパニエルやボクサー。最大90%がカルニチン欠乏症の可能性があります）。 * **猫の肝リピドーシス**（肝臓の脂質代謝とクリアランスを促進します）。 * **ドキソルビシン誘発性心毒性**に対する保護。 * **バルプロ酸毒性**の補助治療。 **臨床のポイント：** L-異性体（レボカルニチン）のみが生物学的に活性であり有益です。D-カルニチンを含むラセミ混合物は、L-カルニチンの取り込みを競合的に阻害し、欠乏症を引き起こす可能性があるため避ける必要があります。
作用機序: 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 → the fatty acids undergo **beta-oxidation** → 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).
動物種別の用量
- Adjunctive dietary therapy in cats with severe hepatic lipidosis · 250 mg PO once daily · PO · q24h · 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 · 250-500 mg/day · PO · q24h
- Trial for treating canine dilated cardiomyopathy (large or giant breed dog) · 2 grams PO q8-12h · PO · q8-12h · Approximately 1 teaspoonful of pure powder
- Adjunctive therapy of dilated cardiomyopathy in American Cocker spaniels · 1 gram PO q8-12h · PO · q8-12h · Give with taurine. Approximately 1/2 teaspoonful.
- Severe myocardial failure in Boxers · 2-3 grams PO q12h · PO · q12h · 2-4 months · To determine if they respond
- Adjunctive treatment of American cocker spaniels with dilated cardiomyopathy · 1 g PO q12h · PO · q12h · Give with taurine 500 mg q12h PO
- Dilated cardiomyopathy in American Cocker spaniels · 1 g PO q8h · PO · q8h
- Dilated cardiomyopathy in Boxer dogs · 2 g PO q8h · PO · q8h
- Documented systemic carnitine deficiency · 50-100 mg/kg PO q8h · PO · q8h
- Myocardial carnitine deficiency only · 200 mg/kg PO q8h · PO · q8h
投与経路
禁忌
- Use of D-carnitine or racemic (D,L) mixtures (competitively inhibits L-carnitine uptake)
有害事象
- Gastrointestinal upset (loose stools, diarrhea, nausea, vomiting) - usually mild and dose-dependent
- Increased body odor (reported in human patients)
薬物相互作用
- Valproic acid · Patients receiving valproic acid may require higher dosages of levocarnitine due to drug-induced carnitine depletion.
モニタリング
- Clinical efficacy (improvement in cardiac or hepatic signs)
- Periodic blood chemistries (recommended in humans, value in veterinary medicine is undetermined)
過量投与
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 の薬剤リファレンスは、獣医療従事者向けの臨床意思決定支援を目的としており、専門的判断やメーカーの最新添付文書に代わるものではありません。