維生素C / 抗壞血酸
**抗壞血酸**（維生素C）是一種水溶性維生素，對膠原蛋白合成、組織修復和抗氧化防禦至關重要。 雖然大多數家畜（如狗、貓、馬）能在肝臟中自行合成足夠的維生素C，但某些物種（最著名的是**天竺鼠、非人類靈長類動物**以及某些蝙蝠和鳥類）缺乏L-古洛糖酸內酯氧化酶，因此需要透過飲食補充。 在獸醫學中，抗壞血酸主要用於： * 治療和預防易感物種（如天竺鼠）的壞血病。 * 在重症監護或溶血事件中作為輔助抗氧化療法。 * 作為尿液酸化劑。 * 協助處理特定毒性反應（例如馬的紅楓葉中毒或普拿疼中毒），因其具有還原變性血紅素的特性。
作用機制: 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.
給藥途徑
禁忌症
- 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)
不良反應
- 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
藥物相互作用
- 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
監測
- 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
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 藥物參考供持牌獸醫專業人員作臨床決策輔助之用,不能取代專業判斷或廠方最新藥品說明書。