ビタミンC / アスコルビン酸
**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.
投与経路
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
薬物相互作用
- Deferoxamine · Concurrent use may exacerbate tissue iron toxicity, particularly in the heart. · major
- Urine acidifying agents · May have additive acidifying effects, potentially increasing the risk of crystalluria. · moderate
モニタリング
- 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)
過量投与
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**.
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。