大觀黴素
大觀黴素（Spectinomycin）是一種**氨基環醇類抗生素（aminocyclitol antibiotic）**，在結構上與氨基糖苷類（aminoglycosides）相似，但缺乏氨基糖和糖苷鍵。 **臨床要點：** * **抑菌與殺菌：** 由於與真正的氨基糖苷類在結構上的差異，大觀黴素是**抑菌劑（bacteriostatic）**而非殺菌劑。 * **安全性：** 它顯著缺乏傳統氨基糖苷類（如慶大黴素或阿米卡星）常見的嚴重腎毒性和耳毒性。 * **抗菌譜：** 對多種革蘭氏陽性和陰性菌（包括大腸桿菌、克雷伯氏菌、變形桿菌、腸桿菌、沙門氏菌、鏈球菌、葡萄球菌和黴漿菌）具有相對廣泛的抗菌活性。 * **局限性：** 對厭氧菌、多數綠膿桿菌、披衣菌或梅毒螺旋體的作用極小或無效。 * **主要用途：** 主要用於經濟動物（豬、家禽、牛）的呼吸道和腸道感染，偶爾也標示外使用於狗、貓和馬。
作用機制: Spectinomycin works by binding to the **30S ribosomal subunit** of susceptible bacteria. **Mechanism Pathway:** Drug enters bacterial cell → Binds specifically to the 30S ribosomal subunit → **Inhibits mRNA translation** and translocation → Halts protein synthesis → **Bacteriostatic effect** (prevents bacterial replication and growth). *Note: Unlike true aminoglycosides, spectinomycin does not cause misreading of the messenger RNA, which explains why its action is bacteriostatic rather than bactericidal.*
各物種劑量
- For acute infectious gastroenteritis · 5-12 mg/kg · IM · q12h
- For bronchopneumonia and fibrinous pneumonia · 33 mg/kg · SC · q8h · Suggested withdrawal time is 60 days.
- For susceptible infections · 22-39.6 mg/kg/day · IM · divided three times daily
- For bovine respiratory disease · 10-15 mg/kg · SC · once daily (q24h) · for 3-5 consecutive days · Inject in the neck; not more than 50 mL per site.
- For susceptible infections · 20 mg/kg · IM · three times daily
- For pneumonia · 20 mg/kg · IM · q8h · May cause local myositis. Insufficient data to comment on use.
- For airsacculitis associated with M. meleagridis or chronic respiratory disease associated with E. coli in turkey poults (1-3 days old) · 0.1 mL (10 mg) · SC · once · Inject in the base of the neck.
- For control and to lessen mortality due to infections from M. synoviae, S. typhimurium, S. infantis, and E. coli in newly hatched chicks · 2.55 mg/0.2 mL · SC · once · Dilute injection with normal saline to a concentration of 2.55 mg/0.2 mL and inject SC.
給藥途徑
禁忌症
- Patients with known hypersensitivity to spectinomycin
不良反應
- Neuromuscular blockade (reversible with parenteral calcium)
- Swelling or soreness at injection sites (especially SC in cattle)
- Transient ataxia (reported in turkey poults at high injected doses)
- Mild increases in BUN, ALP, and SGPT (reported in humans)
- Decreases in hemoglobin, hematocrit, and creatinine clearance (reported in humans)
藥物相互作用
- chloramphenicol · Antagonism has been reported when used concurrently.
- tetracycline · Antagonism has been reported when used concurrently.
監測
- Clinical efficacy (resolution of infection symptoms)
- Injection site monitoring for swelling or myositis
過量
Because the drug is negligibly absorbed after oral administration, **significant systemic toxicity is highly unlikely via the oral route**. Injected overdoses may cause neurological or neuromuscular signs. For example, injected doses of 90 mg produced transient ataxia in turkey poults. If severe neuromuscular blockade occurs following massive parenteral overdose, parenteral calcium administration may be required to reverse the blockade.
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