硫酸亞鐵
硫酸亞鐵是一種口服鐵劑，在獸醫學中主要用於治療**缺鐵性貧血**（通常繼發於慢性失血，如嚴重的跳蚤/鉤蟲感染或胃腸道出血），並作為接受**紅血球生成素 (epoetin)** 治療的慢性腎病患畜的輔助療法。 **臨床要點：** 口服鐵劑的劑量計算容易混淆。必須區分*鐵鹽*（硫酸亞鐵）劑量和*元素鐵*劑量。一般硫酸亞鐵含有約 20% 的元素鐵（每克含 200 毫克元素鐵），而乾燥（脫水）硫酸亞鐵含有約 30% 的元素鐵（每克含 300 毫克元素鐵）。
作用機制: Iron is an essential trace mineral required for the transport and utilization of oxygen. Dietary or supplemental iron is absorbed primarily in the **duodenum** and proximal jejunum → binds to the transport protein **transferrin** in the plasma → transported to the bone marrow → incorporated into porphyrin to form **heme**. Heme is a critical component of **hemoglobin** (in red blood cells) and **myoglobin** (in muscle). Ionized iron also acts as an essential cofactor for several metabolic enzymes, including **cytochrome oxidase**, **succinic dehydrogenase**, and **xanthine oxidase**. While iron does not directly stimulate erythropoiesis, it provides the necessary building blocks to correct hemoglobin deficits caused by iron deficiency.
各物種劑量
- Hematinic · 0.5-2 g PO per day · PO · q24h · 2 weeks or more
- Iron deficiency anemia · 50-100 mg (total dose) PO once daily · PO · q24h
- Iron deficiency anemia · 30-200 mg (total dose) PO per day · PO · q24h · 2 weeks or more
- Adjunct to epoetin (erythropoietin) therapy · 50-100 mg (total dose) PO per day · PO · q24h · Many cats do not tolerate oral iron therapy and are better treated with iron dextran at 50 mg IM q3-4 weeks.
- Adjunct to epoetin (erythropoietin) therapy · 5-50 mg per cat PO once daily · PO · q24h
- Adjunct to epoetin (erythropoietin) therapy · 50-100 mg per cat PO once daily · PO · q24h
- Adjunct to epoetin (erythropoietin) therapy · 10 mg/kg PO once daily · PO · q24h
- Hematinic · 8-15 g PO per day · PO · q24h · 2 weeks or more
- Hematinic · 2-8 g PO per day · PO · q24h · 2 weeks or more
劑量為合格獸醫專業人員的臨床參考。請務必對照最新藥品仿單及個別病患確認。
給藥途徑
禁忌症
- Hemosiderosis
- Hemochromatosis
- Hemolytic anemias
- Known hypersensitivity to iron products
- Gastrointestinal ulcerative diseases (relative contraindication due to GI irritation)
不良反應
- Mild gastrointestinal upset (nausea, vomiting)
- Black or dark-colored feces (normal and harmless)
- Constipation or diarrhea
藥物相互作用
- Antacids · May bind to iron and decrease oral absorption; administer at least two hours apart.
- Calcium (Oral) · May bind to iron and decrease oral absorption; administer at least two hours apart.
- Chloramphenicol · May delay the response to iron administration; avoid using in patients with iron deficiency anemia.
- Fluoroquinolones (e.g., enrofloxacin) · Iron may significantly reduce the absorption of oral fluoroquinolones; administer at least two hours apart.
- H2-Receptor Antagonists (e.g., famotidine) · Increased gastric pH may decrease iron absorption.
- Penicillamine · Iron can decrease the efficacy of penicillamine by decreasing its absorption; space doses as far apart as possible.
- Proton-Pump Inhibitors (e.g., omeprazole) · Increased gastric pH may decrease iron absorption.
- Tetracyclines · Oral iron preparations can bind to orally administered tetracyclines, decreasing the absorption of both compounds.
- Thyroxine · Iron may reduce the absorption of oral thyroxine; administer at least two hours apart.
- Vitamin C (Ascorbic Acid) · May enhance the gastrointestinal absorption of iron.
監測
- Clinical efficacy (resolution of anemia signs)
- Hemograms (CBC)
- Serum iron (Normal: Dogs 80-180 mcg/dL, Cats 70-140 mcg/dL)
- Total iron binding capacity (TIBC) (Normal: Dogs 280-340 mcg/dL, Cats 270-400 mcg/dL)
- Serum transferrin saturation
過量
Ingestion of iron-containing products can result in **life-threatening toxicity**. As little as 400 mg of elemental iron can be fatal in a child. **Clinical Signs of Toxicity:** * **Phase 1 (30 mins to several hours):** Acute gastrointestinal irritation, distress, vomiting (possibly hemorrhagic), abdominal pain, and diarrhea. * **Phase 2 (12-48 hours):** The patient may appear asymptomatic, but this can be a deceptive latent phase. * **Phase 3:** Peripheral vascular collapse, hypotension, cyanosis, pulmonary edema, fulminant hepatic failure, coma, and death. * **Long-term Sequelae:** Animals that survive may exhibit gastric scarring, strictures, and persistent digestive disturbances. **Treatment:** * Must be handled as an absolute emergency. * **Decontamination:** Empty the stomach using gastric lavage with a large bore tube (avoid emetics if hemorrhagic vomiting is already present). Lavage with tepid water or 1-5% sodium bicarbonate solution. * Oral milk of magnesia may help bind the drug in the GI tract. * **Antidote:** **Deferoxamine** is a specific chelating agent used to bind absorbed iron. * **Supportive Care:** IV fluids for shock, treatment of acidosis, prophylactic antibiotics, oxygen, and management of coagulation abnormalities or seizures.
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