替米考星
**替米考星 (Tilmicosin)** 是一種由泰樂菌素 (tylosin) 合成而來的半合成**巨環類抗生素**，主要在獸醫學中用於治療由*溶血性曼海姆菌*、*多殺性巴斯德桿菌*和*睡眠組織嗜血桿菌*引起的牛和羊呼吸道疾病 (BRD)。 * **主要特點**： * 具有高度脂溶性，能廣泛穿透組織。它會主動集中在**肺部組織**和肺泡巨噬細胞中，為呼吸道感染提供標靶治療。 * 主要透過**皮下 (SC)** 注射投予反芻動物，或作為含藥飼料添加劑投予豬隻。 > **嚴厲警告**：替米考星在許多物種中的安全範圍很窄。人類、豬、馬、駱駝科動物和非人類靈長類動物若意外注射，可能會因嚴重心血管毒性而**迅速致命**。
作用機制: Tilmicosin exerts its bacteriostatic effect by penetrating the bacterial cell membrane and reversibly binding to the **50S ribosomal subunit**. * **Mechanism**: Binds to the **50S subunit** → blocks the exit tunnel for newly synthesized peptides → inhibits translocation of peptidyl-tRNA → **premature termination of bacterial protein synthesis**. * It exhibits time-dependent antibacterial activity and has a prolonged post-antibiotic effect (PAE), especially against respiratory pathogens. Its accumulation in macrophages allows it to be delivered directly to the site of infection via chemotaxis.
各物種劑量
- Susceptible infections · 10 mg/kg SC (not more than 15 mL per injection site). · SC · Single dose · Subcutaneous injection under the skin in the neck, or if not accessible, behind the shoulders and over the ribs is suggested. Do not use in lambs less than 15 kg of body weight.
- Treatment of pneumonic pasteurellosis · 10 mg/kg SC every 72 hours · SC · q72h · Subcutaneous injection under the skin in the neck, or if not accessible, behind the shoulders and over the ribs is suggested.
- Susceptible infections · 10 mg/kg SC (not more than 15 mL per injection site) · SC · Single dose
- Susceptible infections (Rabbits) - Regimen 1 · 25 mg/kg SC once; repeat in 3 days if necessary. · SC · Once, repeat in 3 days PRN · Can cause weakness, pallor, tachypnea and sudden death. May cause acute death if given IV. SC injections can cause local swelling and necrosis.
- Susceptible infections (Rabbits) - Regimen 2 · 5 mg/kg SC on day 0, if no reaction, give 10 mg/kg SC on days 7 and 14. · SC · Days 0, 7, 14 · 14 days · Can cause weakness, pallor, tachypnea and sudden death. May cause acute death if given IV. SC injections can cause local swelling and necrosis.
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給藥途徑
禁忌症
- Intravenous (IV) administration (can be fatal)
- Use in automatically powered syringes
- Injection in swine, non-human primates, horses, and camelids
- Use in lactating ewes if milk is intended for human consumption
- Use in veal calves
- Use in female dairy cattle 20 months or older
不良反應
- Local tissue reaction and trim loss (if given IM)
- Edema at the site of subcutaneous injection
- Severe cardiovascular toxicity (fatalities) if given IV
- Fatalities in swine, non-human primates, and potentially horses if injected
- Severe reactions in camelids
藥物相互作用
- Epinephrine · Increased mortality associated with tilmicosin in swine.
- Other Macrolides / Lincosamides · Potential cross-resistance and competitive binding at the 50S ribosomal subunit (extrapolated from erythromycin).
監測
- Clinical efficacy (resolution of respiratory signs)
- Injection site reactions
- Slaughter withdrawal times (28 days for cattle/sheep injection; 7 days for swine feed)
過量
The **cardiovascular system** is the primary target of acute toxicity, likely due to calcium channel blockade leading to negative inotropic effects, tachycardia, and fatal arrhythmias. * **Cattle**: Doses up to 50 mg/kg IM did not cause death, but SC doses of 150 mg/kg caused fatalities, as did IV doses of 5 mg/kg. * **Swine**: Doses as low as 10 mg/kg caused increased respiration, emesis, and seizures; 20 mg/kg IM caused death in most animals tested. * **Monkeys**: 10 mg/kg caused no signs of toxicity; 20 mg/kg caused vomiting; 30 mg/kg caused death. > **HUMAN EXPOSURE**: In cases of human injection, **contact a physician immediately**. Apply ice to the injection site. Emergency medical telephone numbers: 1-800-722-0987 or 1-317-276-2000.
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