聚苯乙烯磺酸鈉
聚苯乙烯磺酸鈉 (SPS) 是一種不被吸收的**陽離子交換樹脂**，主要作為獸醫病患高血鉀症（血液中鉀離子過高）的輔助治療。 > **臨床要點：** 由於其作用緩慢（需數小時至數天），SPS **不應**作為急性、危及生命的高血鉀症的單一療法。在緊急情況下，應優先使用作用更快的療法（例如靜脈注射葡萄糖酸鈣、常規胰島素加葡萄糖，或碳酸氫鈉）。 重點： * 它的作用機制是在胃腸道中將鈉離子與鉀離子進行交換。 * 口服時通常會與瀉藥（如山梨醇）一起給予，以防止便秘並加速樹脂-鉀複合物的排出。 * 必須始終找出並同時治療導致高血鉀的潛在原因（例如急性腎損傷、尿道阻塞、腎上腺皮質機能低下）。
作用機制: SPS acts as a cation exchange resin in the gastrointestinal tract. * **Mechanism:** After oral or rectal administration, the resin exchanges its **sodium ions** for hydrogen ions in the acidic environment of the stomach. As it travels into the large intestine, where potassium concentration is higher, it exchanges these ions for **potassium ions**. * **Binding Capacity:** While theoretically capable of exchanging up to 3.1 mEq of potassium per gram, in vivo it typically exchanges approximately **1 mEq of potassium per gram** of resin. * **Excretion:** The resin, now bound to potassium, is excreted unchanged in the feces, thereby physically removing potassium from the body. * **Sodium Load:** Because it releases sodium in exchange for potassium, it delivers a significant sodium load to the patient, which can be problematic in sodium-restricted individuals.
各物種劑量
- Life-threatening hyperkalemia in neonatal foals · 15 grams of resin in 100 mL of 10% dextrose · Enema · Once/As directed · As needed · Monitor serum potassium and sodium closely.
- Hyperkalemia · 2 grams of resin/kg divided into 3 daily doses (suspended in 3-4 mL water/gram or commercial suspension). Severe hyperkalemia: 3-4 times the normal amount may be given. · PO/Enema · q8h · As needed · If PO, give with a cathartic. If enema, do NOT use a cathartic (must retain in colon for at least 30 mins). Enema prep: add 15g per 100 mL of 1% methylcellulose or 10% dextrose.
- Mild hyperkalemia (<6 mEq/L) · 2 grams/kg in 3-4 divided doses with 20% sorbitol · PO/Enema · q6-8h · As needed · May also be given as an enema without sorbitol.
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
- Patients on severely restricted sodium diets
- Severe congestive heart failure (CHF)
- Severe hypertension
- Oliguric or anuric acute kidney injury (where sodium load cannot be excreted)
- Conditions predisposing to severe constipation or bowel obstruction
不良反應
- Constipation (fecal impaction reported rarely)
- Anorexia
- Vomiting
- Nausea
- Hypokalemia (from overuse)
- Hypocalcemia
- Hypomagnesemia
- Sodium retention / Hypernatremia
藥物相互作用
- Antacids (Calcium or Magnesium containing) · SPS may bind with magnesium or calcium, preventing bicarbonate ion neutralization and potentially leading to systemic metabolic alkalosis. Concurrent use is not recommended.
- Laxatives (Calcium or Magnesium containing) · Similar to antacids, can lead to metabolic alkalosis and reduced potassium-binding efficacy.
監測
- Serum electrolytes (sodium and potassium at least once daily; calcium, magnesium)
- Acid/base status
- ECG (if warranted to monitor cardiac effects of hyper/hypokalemia)
- Fecal output and consistency (monitor for constipation/impaction)
過量
Overdosage or overuse may lead to severe electrolyte imbalances, including **hypokalemia** (low potassium), **hypocalcemia** (low calcium), and **hypomagnesemia** (low magnesium), as well as significant **sodium retention**. Treatment is symptomatic and supportive. Discontinue the drug immediately and correct electrolyte deficits based on frequent serum chemistry monitoring.
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