ビタミンC / アスコルビン酸
Ascorbic Acid
L-ascorbic acid
別名: Vitamin C · Ascor L 500 · L-ascorbic acid · Antiscorbutic vitamin · Ascorbate
VetSheet 獣医チームが監修更新日 2026年4月5日エビデンスに基づく獣医学リファレンス
動物種別用量
この薬剤の用量データは VetSheet の薬事集にまだ収載されていません。以下のその他の項目は完全です。処方前に最新の添付文書をご確認ください。
概要
アスコルビン酸（ビタミンC）は、コラーゲン合成、組織修復、抗酸化防御に不可欠な水溶性ビタミンです。
犬、猫、馬などの多くの動物は体内で十分なビタミンCを合成できますが、モルモットや霊長類、一部のコウモリや鳥類などの特定の動物は合成酵素（L-グロノラクトンオキシダーゼ）を持たないため、食事からの摂取が必要です。
獣医療では、主に以下の目的で使用されます：
- モルモットなどの感受性動物における壊血病の治療と予防。
- 救急医療や溶血性疾患における補助的な抗酸化療法。
- 尿の酸性化。
- メトヘモグロビン還元作用を活かした特定の薬物中毒（馬のレッドメープル中毒やアセトアミノフェン中毒など）の管理。
作用機序
Ascorbic acid acts as a vital coenzyme and a powerful water-soluble antioxidant.
- Collagen Synthesis: It is an essential cofactor for the enzymes prolyl hydroxylase and lysyl hydroxylase → facilitates the hydroxylation of proline and lysine residues → allows for the formation of a stable collagen triple helix.
- Antioxidant Activity: Scavenges reactive oxygen species (ROS) → protects lipid membranes, DNA, and proteins from oxidative damage.
- Methemoglobin Reduction: Assists in the reduction of methemoglobin back to functional hemoglobin, which is beneficial in certain oxidative toxicities.
- Iron Absorption: Enhances the gastrointestinal absorption of non-heme iron and regulates iron transport.
安全性・警告
禁忌
- Patients with a history of urate or calcium oxalate urolithiasis
- Use with caution in patients with iron storage diseases (e.g., hemochromatosis)
- Patients with a history of calcium oxalate or urate urolithiasis (due to urine acidification)
有害事象
- Gastrointestinal upset (diarrhea) with high oral doses
- Pain or tissue irritation at the injection site (IM or SC)
- Increased risk of calcium oxalate urolithiasis with chronic high-dose administration
- Gastrointestinal upset (diarrhea) at high oral doses
- Pain at injection site (IM/SC)
- Potential to acidify urine, which may increase the risk of oxalate or urate urolithiasis
注意事項
Use with extreme caution in animals prone to calcium oxalate urolithiasis, as ascorbic acid is partially metabolized to oxalate and excreted in the urine. Intravenous administration should be performed slowly to avoid adverse cardiovascular events. Injectable solutions should be protected from light.
医薬品相互作用
Concurrent use may exacerbate tissue iron toxicity, particularly in the heart.
May have additive acidifying effects, potentially increasing the risk of crystalluria.
監視
- Clinical signs of disease resolution (e.g., improvement of scurvy symptoms in guinea pigs)
- Urine pH (if utilized specifically as a urinary acidifier)
- Resolution of clinical signs of scurvy (in susceptible species)
- Urine pH (if using high doses)
薬物動態
半減期
吸収
Readily absorbed from the gastrointestinal tract (primarily the jejunum) via active transport mechanisms.
分布
Widely distributed to all body tissues; particularly high concentrations are found in glandular tissue, leukocytes, the liver, and the lens of the eye.
代謝
Reversibly oxidized to dehydroascorbic acid; partially metabolized in the liver to inactive compounds, including oxalic acid.
消失
Excreted primarily in the urine. A renal threshold exists; once tissue saturation is reached, excess ascorbic acid is excreted unchanged in the urine.
過剰投与
Ascorbic acid is generally very safe due to its water-soluble nature; excess amounts are rapidly excreted in the urine. Massive acute overdoses may cause gastrointestinal disturbances (such as diarrhea) or mild acidosis. Chronic overdosage significantly increases the risk of calcium oxalate urolithiasis.
製品
製剤
- Injection: 500 mg/mL in 50 mL vials (0.025% EDTA, preservative-free)
- Injectable: 100 mg/ml
- Oral: various strength tablets, capsules, powders and liquids
動物用医薬品
- Ascor L 500® (McGuff): 500 mg/mL injection in 50 mL vials
- Various injectable solutions (100 mg/ml) (POM)
- Various oral supplements (General Sale)
ヒト用医薬品
- Various over-the-counter oral tablets, capsules, chewables, and liquids
- Generic injectable formulations
- Various tablets, capsules, chewables, powders, and liquids
規制ステータス
Injectable forms are typically POM (Prescription Only Medicine), while oral forms are General Sale.
Injectable forms are POM-V; oral forms are General Sale List (GSL).
規制データなし: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
保管・安定性
Store intact vials at controlled room temperature and protect from light. Preservative-free solutions should be used promptly after opening, and any unused portion should be discarded.
飼主向け情報
重要なポイント: ほとんどの犬や猫は体内でビタミンCを合成できるため、獣医師の指示がない限りサプリメントは不要です。
- モルモットは自分でビタミンCを作ることができないため、毎日の食事や専用のサプリメントでの補給が必要です。
- ビタミンCは光や空気に触れると劣化しやすいため、涼しく暗い場所に保管してください。
- 高用量が処方された場合、便の状態を観察し、下痢が見られたら獣医師に相談してください。
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