鏈脲佐菌素
鏈脲佐菌素是一種最初源自*Streptomyces achromogenes*的**抗腫瘤抗生素**，儘管市售產品為人工合成。在獸醫學中，它主要利用其對胰腺β細胞的靶向毒性，成為治療犬隻**復發性、無法手術切除或轉移性胰島素瘤**的關鍵藥物。 * **臨床要點**：胰島素瘤是分泌過量胰島素的胰腺功能性腫瘤，會導致危及生命的低血糖。鏈脲佐菌素能選擇性破壞這些腫瘤細胞，有助於控制低血糖並減緩腫瘤進展。 * 由於其嚴重的毒性特徵，通常僅保留用於手術切除不完全或無法手術的難治性病例。
作用機制: Streptozocin acts primarily as an **alkylating agent**. * **DNA Damage**: It cross-links DNA strands → inhibits **DNA synthesis** and prevents precursor incorporation into DNA. * **Beta-Cell Toxicity**: The drug enters cells via the **GLUT2 transporter**, which is highly expressed on pancreatic beta cells. Once inside, it causes a species-specific diabetogenic effect in dogs by reducing **nicotinamide adenine dinucleotide (NAD)** and ATP concentrations → irreversible beta cell necrosis. * While it possesses antibacterial activity against gram-positive and gram-negative bacteria, its severe cytotoxicity precludes its use as an antibiotic.
各物種劑量
- Recurrent insulinoma after surgery (investigational) · Begin saline diuresis: Give normal saline at 18-20 mL/kg/hour for 7-8 hours. Over the 4th-5th hour, give streptozocin in the saline solution at a dose of 500 mg/m 2 IV. Give an antiemetic (e.g., butorphanol) at the end of the 7-hour period. · IV · Once · 7-8 hours total · Requires aggressive fluid therapy.
- Pancreatic islet cell tumors · Normal saline is given IV at 18.3 mL/kg/hr for 3 hours, then streptozocin is administered at 500 mg/m 2 over two hours with the saline diuresis continuing. After streptozocin infusion completed, continue saline diuresis for another 2 hours. Butorphanol is administered as an antiemetic immediately after streptozocin. · IV · May repeat at 3 week intervals · Until evidence of tumor progression, recurrence of hypoglycemia, or drug toxicity · Monitor for myelosuppression and nephrotoxicity.
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 without a confirmed histologic diagnosis of insulinoma
- Patients with completely resectable tumors
- Pregnancy (unless benefits outweigh risks; FDA Category C)
不良反應
- Serious, permanent renal toxicity
- Severe and protracted vomiting and nausea
- Mild myelosuppression
- Elevated liver enzymes
- Severe tissue necrosis if extravasated (vesicant)
藥物相互作用
- Doxorubicin · Streptozocin may prolong the half-life of doxorubicin; dosage adjustment may be required.
- Myelosuppressive drugs (e.g., carmustine) · Additive or synergistic myelosuppression may occur.
- Nephrotoxic drugs (aminoglycosides, amphotericin B, cisplatin) · May cause additive nephrotoxicity when used concurrently.
- Niacinamide (nicotinamide) · Can block the diabetogenic effects of streptozocin without altering its antineoplastic activity; this may be beneficial or detrimental depending on the clinical goal.
監測
- Blood glucose (to assess efficacy)
- Baseline and post-treatment renal function tests (including urinalysis)
- CBC (for myelosuppression)
- Baseline and pre-retreatment liver function tests
- Hydration status (especially for the first few days after treatment or if vomiting is a problem)
過量
Severe toxicity may result if acutely overdosed, primarily manifesting as **acute renal failure**, **severe gastrointestinal distress**, and **myelosuppression**. Dosages must be calculated carefully based on body surface area (m^2). Treatment is supportive, focusing on aggressive fluid diuresis and management of uremia and cytopenias.
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