ポリスチレンスルホン酸ナトリウム
ポリスチレンスルホン酸ナトリウム（SPS）は、主に獣医療において高カリウム血症（血中カリウム濃度が異常に高い状態）の補助治療として使用される、非吸収性の**陽イオン交換樹脂**です。 > **臨床上のポイント：** 効果が現れるまでに時間がかかる（数時間から数日）ため、SPSは急性で生命を脅かす高カリウム血症の単独治療として使用するべきではありません。緊急時には、より即効性のある治療（静脈内グルコン酸カルシウム、レギュラーインスリンとブドウ糖、または炭酸水素ナトリウムなど）を優先する必要があります。 重要なポイント： * 胃腸管内でナトリウムイオンとカリウムイオンを交換することで作用します。 * 経口投与の場合、便秘を防ぎ樹脂とカリウムの複合体の排出を促進するため、下剤（ソルビトールなど）と一緒に投与されることがよくあります。 * 高カリウム血症の根本的な原因（急性腎障害、尿路閉塞、副腎皮質機能低下症など）を常に特定し、同時に治療する必要があります。
作用機序: 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.
動物種別の用量
- 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.
用量は獣医療従事者向けの臨床リファレンスです。必ず最新の添付文書と個々の患者で確認してください。
投与経路
禁忌
- 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
有害事象
- Constipation (fecal impaction reported rarely)
- Anorexia
- Vomiting
- Nausea
- Hypokalemia (from overuse)
- Hypocalcemia
- Hypomagnesemia
- Sodium retention / Hypernatremia
薬物相互作用
- 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.
モニタリング
- 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)
過量投与
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.
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。