柳氮磺吡啶 / 磺胺沙拉嗪
柳氮磺吡啶 (Sulfasalazine) 是一種獨特的局部作用前驅藥，透過偶氮鍵結合了磺胺類抗生素（**磺胺吡啶**）和水楊酸類抗發炎藥（**美沙拉嗪**或 **5-ASA**）。 - **主要用途**：它是治療犬貓**特發性炎症性腸病 (IBD)**，特別是**漿細胞-淋巴細胞性結腸炎**（大腸性腹瀉）的基石療法。也曾作為犬血管炎的輔助治療。 - **限制**：對小腸疾病無效，因為它需要結腸細菌來活化。 - **臨床要點**：雖然對結腸炎非常有效，但在獸醫學中使用需要仔細監測，因為有導致犬隻發生**乾眼症 (KCS)** 的風險，若未及早發現可能造成不可逆的傷害。貓對水楊酸鹽天生敏感，因此需要謹慎給藥。
作用機制: Sulfasalazine acts as a targeted delivery vehicle to transport anti-inflammatory medication directly to the colon. - **Delivery**: The intact drug passes mostly unabsorbed (only 10-33% absorbed) through the stomach and small intestine. - **Activation**: In the colon, **bacterial azoreductase enzymes** cleave the diazo bond. - **Mechanism**: - **5-Aminosalicylic Acid (5-ASA / Mesalamine)** → Acts locally on the colonic mucosa to inhibit **cyclooxygenase (COX)** and **lipoxygenase (LOX)** pathways → Decreases production of pro-inflammatory **prostaglandins** and **leukotrienes**. It also acts as a local free radical scavenger. - **Sulfapyridine** → Provides local antibacterial effects, though it is rapidly absorbed systemically and is responsible for the majority of the drug's adverse effects (e.g., KCS, hepatotoxicity).
各物種劑量
- Inflammatory large bowel disease · 10-20 mg/kg PO once daily. · PO · q24h · Unspecified · Use cautiously in cats because of their sensitivity to salicylates.
- Inflammatory large bowel disease · 10-20 mg/kg PO q24 hours (once daily) tapered to the lowest effective dose · PO · q24h · Unspecified
- Inflammatory large bowel disease · 10-20 mg/kg PO q8-12h (maximum of 10 days) · PO · q8-12h · Maximum 10 days
- Inflammatory large bowel disease · 10-20 mg/kg PO q8-24h; up to a maximum of 10 days treatment · PO · q8-24h · Maximum 10 days
- All uses (Management of colitis) · 10-20 mg/kg · PO · q8-12h
- General · 10-20 mg/kg PO 2-3 times a day · PO · q8-12h · Unspecified
- General · 25 mg (total dose) PO twice daily · PO · q12h · Unspecified
- Inflammatory large bowel disease · 20-40 mg/kg PO q8h for 3 weeks, followed by 20-40 mg/kg q12h for 3 weeks, and 10-20 mg/kg q12h for 3 weeks. · PO · q8h then q12h · 9 weeks
- Inflammatory large bowel disease · 20-48.4 mg/kg (maximum total dose of one gram in refractory patients) PO q8h. · PO · q8h · Minimum 4 weeks · May consider an initial dose of 12.5 mg/kg, q8h. After signs resolve, reduce dosage by 25% at 2 week intervals.
給藥途徑
禁忌症
- Hypersensitivity to sulfasalazine, sulfonamides, or salicylates
- Intestinal or urinary obstructions
- Doberman pinschers (highly susceptible to sulfonamide-induced polysystemic immune complex disease)
- Dobermanns (appear to be highly sensitive to adverse effects associated with sulfapyridine)
- Patients with known hypersensitivity to sulfonamides or salicylates
不良反應
- Keratoconjunctivitis sicca (KCS) in dogs
- Anorexia
- Vomiting
- Cholestatic jaundice
- Hemolytic anemia
- Leukopenia
- Decreased sperm counts
- Allergic dermatitis
- Keratoconjunctivitis sicca (KCS)
藥物相互作用
- Chlorpropamide · Hypoglycemic effects could be potentiated
- Digoxin · Sulfasalazine may reduce absorption of digoxin · moderate
- Ferrous sulfate (or other iron salts) · May decrease the blood levels of sulfasalazine if administered concurrently
- Folic acid · Oral absorption of folic acid may be inhibited
- Warfarin · Potentially sulfasalazine could potentiate warfarin
- Folate · Measurement of serum folate concentration may be affected · minor
- Thyroxine · May cause a reduction in serum thyroxine concentrations · minor
監測
- Clinical efficacy (resolution of diarrhea/colitis signs)
- Schirmer tear tests (STT) prior to therapy and on rechecks (especially in middle-aged to older dogs) to monitor for KCS
- Complete Blood Count (CBC) occasionally with chronic therapy
- Liver function tests occasionally with chronic therapy
- Schirmer tear test (STT) periodically
- Clinical signs of KCS (ocular discharge, blepharospasm)
- Liver enzymes (due to risk of cholestatic jaundice)
- Thyroid panel (if on long-term therapy)
過量
Massive overdoses could cause significant **salicylate and/or sulfonamide toxicity**. - **Treatment**: Standard protocols for decontamination (empty stomach, cathartics, etc.) should be considered. - **Supportive Care**: Urine alkalinization and forced diuresis may be beneficial in selected cases to enhance elimination.
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