多殺菌素
多殺菌素 (Spinosad) 是一種全身性口服大環內酯類殺蟲劑，源自天然土壤細菌 *Saccharopolyspora spinosa*。主要用於預防和治療犬隻的跳蚤 (*Ctenocephalides felis*) 感染。 **主要臨床優勢：** * **起效迅速：** 30分鐘內開始殺死跳蚤，4小時內完全殺滅，能在成蟲產卵前將其殺死，有效打破跳蚤生命週期。 * **防水性佳：** 由於是全身性（口服）給藥，其療效完全不受游泳、洗澡或使用皮膚病洗毛精的影響。 **臨床要點：** * 雖然主要作為除蚤成蟲劑，但初步研究顯示，在較高的仿單標示外劑量下，24小時內對壁蝨 (*R. sanguineus*) 也有很高的殺滅效果（儘管未正式標示用於控制壁蝨）。 * *貓咪使用注意事項：* 雖然本專論指出未核准用於貓，但 FDA 後來已核准了貓專用的 Comfortis 劑型。請務必參考最新的產品標示以獲取貓咪劑量資訊。
作用機制: Spinosad targets the insect nervous system through a unique mechanism distinct from other parasiticides: * **Primary Pathway:** Acts as an agonist at the **nicotinic acetylcholine D-alpha receptors** → causes motor neuron activation → leads to involuntary muscle contractions and tremors → prolonged exposure results in paralysis and rapid flea death. * **Secondary Pathway:** Opens **GABA-gated chloride channels** in insects, similar to the mechanism of other macrocyclic lactones, further contributing to neuromuscular paralysis. Because mammalian nicotinic receptors are structurally different from insect receptors, spinosad exhibits a high margin of safety in dogs.
各物種劑量
- Flea infestation · 50-75 mg/kg · PO · q28d · Give with or immediately after food.
- Prevention or treatment of fleas infestations · 30-60 mg/kg (minimum dosage of 30 mg/kg) PO once monthly with food. · PO · q30d · 1 month · Must be given with food for optimal absorption.
- Flea infestation · 45-70 mg/kg · PO · q28d · Give with or immediately after food.
劑量為持牌獸醫專業人員的臨床參考。請務必對照最新藥品說明書及個別病患確認。
給藥途徑
禁忌症
- Cats (per this specific monograph's label status)
- Dogs with known pork or soy allergies (chewable tablets contain pork proteins and hydrolyzed soy)
- Dogs and cats weighing < 1.2 kg
- Dogs and cats < 14 weeks of age
- Dogs with MDR1 mutation (relative contraindication due to increased risk of adverse effects)
不良反應
- Vomiting (most common)
- Depression/lethargy
- Anorexia
- Ataxia
- Diarrhea
- Pruritus
- Trembling
- Hypersalivation
- Seizures (rare)
- Vomiting (occasional)
- Lethargy (rare)
- Diarrhoea (rare)
- Anorexia (rare)
- Ataxia (rare)
藥物相互作用
- Ivermectin · Concurrent use with high extra-label doses of ivermectin (e.g., for demodicosis) increases the risk of neurotoxicity. However, spinosad is safe to use with standard low-dose heartworm preventatives.
- Macrocyclic lactones (e.g., avermectins, ivermectin) · Increased risk of severe neurological toxicity. Do not use in combination. · major
- Digoxin · Competition for P-glycoprotein efflux pump, potentially increasing digoxin levels. · moderate
- Doxorubicin · Competition for P-glycoprotein efflux pump, potentially increasing doxorubicin toxicity. · moderate
監測
- Flea control efficacy
- Adverse gastrointestinal or neurologic effects
- Efficacy of flea control
- Gastrointestinal tolerance (vomiting)
- Adverse neurological signs
過量
Spinosad has a wide margin of safety. The oral LD50 in mice is >5000 mg/kg. In canine dose tolerance studies (up to 16.7X the normal dose for 10 days), the primary sign was **routine vomiting**. No significant changes in hematology or coagulation were noted, though mild elevations in ALT and phospholipidosis (vacuolation) of lymphoid tissue occurred.
VetSheet 藥物參考供持牌獸醫專業人員作臨床決策輔助之用,不能取代專業判斷或廠方最新藥品說明書。