목시덱틴

아버멕틴계 항기생충약

**목시덱틴(Moxidectin)**은 소동물 및 대동물 수의학에서 광범위하게 사용되는 강력한 2세대 매크로라이드계(아버멕틴/밀베마이신 하위 클래스) 항기생충 약물입니다. 주요 약리학적 특징은 다음과 같습니다: * **광범위한 효능**: 다양한 체내 선충(회충, 구충, 편충, 심장사상충 유충) 및 체외 절지동물(벼룩, 진드기, 이, 소파리 유충)에 효과적입니다. * **높은 지용성**: 목시덱틴은 이버멕틴보다 약 100배 더 높은 지용성을 가집니다. 이로 인해 조직에 광범위하게 분포하고 반감기가 연장되며, 서방형 제제(예: 6개월 지속형 심장사상충 예방 주사)의 개발이 가능합니다. * **ABCB1 (MDR1) 안전성**: ABCB1-1∆ 유전자 돌연변이가 있는 개는 매크로라이드계 약물에 민감하지만, FDA 승인을 받은 표준 라벨 용량(바르는 약 및 경구용 심장사상충 예방)의 목시덱틴은 이러한 품종에도 일반적으로 안전한 것으로 간주됩니다. 그러나 라벨 외 고용량 사용(예: 모낭충증 치료)은 심각한 신경 독성을 유발할 수 있습니다. 바르는 스팟온(주로 이미다클로프리드와 혼합), 서방형 주사제, 경구용 겔, 푸어온(등에 붓는) 용액 등 다양한 제형으로 제공됩니다.

작용 기전: Moxidectin exerts its antiparasitic effects by disrupting the neurological function of invertebrates: * **Glutamate-Gated Chloride Channels (GluCl)**: Moxidectin binds selectively and with high affinity to GluCl channels present in invertebrate nerve and muscle cells → **increases membrane permeability to chloride ions** → causes cellular hyperpolarization → results in flaccid paralysis and death of the parasite. * **GABA Receptors**: It also enhances the release of gamma-aminobutyric acid (GABA) at presynaptic neurons, further blocking post-synaptic stimulation. **Mammalian Safety**: Mammals do not possess GluCl channels. Furthermore, the **P-glycoprotein (P-gp)** efflux pump at the mammalian blood-brain barrier actively prevents moxidectin from entering the central nervous system, protecting mammalian GABA receptors from exposure.

동물 종별 용량

Cats

Prevention of heartworm disease, adult fleas, ear mites, hookworms, and roundworms (Advantage Multi) · 10 mg/kg imidacloprid/1 mg/kg moxidectin once a month by topical administration · topical · q30d · For cats 2-5 lb = 0.23 mL; 5.1-9 lb = 0.4 mL; 9.1-18 lb = 0.8 mL.
Feline Aelurostrongylosis (Aelurostrongylus abstrusus) · One to three topical applications of 1 mg/kg moxidectin (in combination with imidacloprid) · topical · 1-3 applications
Flea, mite, nematode treatment and heartworm prevention · 10 mg/kg body weight imidacloprid and 1.0 mg/kg body weight moxidectin · topical · monthly · Ongoing for prevention · Apply via spot-on pipette. Severe effects may be seen if applied to cats with adult heartworm disease.
Flea/tick control and heartworm/nematode prevention (Bravecto Plus) · 280 mg/ml fluralaner and 14 mg/ml moxidectin (volume based on weight) · topical · q12w for flea/tick control, q8w for heartworm prevention · Ongoing · Not for use in kittens <9 weeks or cats <1.2 kg.

Sheep

Internal parasites · 0.2 mg/kg [1 mL per 11 lb (1 mL per 5 kg) bodyweight] PO (drench) · PO · single dose
Gastrointestinal helminthes in Camelids (NWC) · 0.2 mg/kg · PO · single dose · Regimen of choice for camelids.

Horses

Gastrointestinal parasites (Oral Gel) · Dial in the weight of the animal on the syringe · PO · single dose · Horses weighing more than 1250 lb require additional gel from a second syringe.

투여 경로

POSCtopicalTopical

금기

Hypersensitivity to the drug
Dogs not tested for heartworm infection prior to use
Sick, debilitated, or underweight dogs (specifically for the 6-month injectable)
Female dairy cattle of breeding age
Horses intended for food purposes
Foals younger than 4 months of age
Kittens < 9 weeks of age
Dogs < 7 weeks of age
Dogs with Class 4 heartworm disease
Cats < 1.2 kg (for fluralaner combination)
Breeding males (for fluralaner combination)

이상반응

Dogs: Lethargy, vomiting, ataxia, anorexia, diarrhea, nervousness, weakness, polydipsia, pruritus
Dogs (Injectable): Rare but serious reports of anaphylaxis, liver disease, autoimmune hemolytic disease, convulsions
Cats: Recumbency (rare)
Horses: Minimal at labeled doses; CNS depression and coma reported in foals at high doses
Cattle: Minimal to nonexistent at labeled doses
Transient pruritus at application site
Erythema at application site
Hypersalivation (if licked)
Emesis and haematemesis
Diarrhoea
Lethargy
Pyrexia
Tachypnoea
Mydriasis
Severe systemic reactions in cats with adult heartworm disease

약물 상호작용

Benzodiazepines · Effects may be potentiated by moxidectin; concurrent use is generally not advised.
P-glycoprotein Inhibitors (Amiodarone, Carvedilol, Clarithromycin, Cyclosporine, Diltiazem, Erythromycin, Itraconazole, Ketoconazole, Quinidine, Spironolactone, Tamoxifen, Verapamil) · May inhibit the efflux pump at the blood-brain barrier, potentially increasing the risk of moxidectin neurotoxicity, especially in dogs with the ABCB1-1∆ mutation.
P-glycoprotein substrates · Increased risk of neurological toxicity due to competitive inhibition at the blood-brain barrier · major
Other macrocyclic lactones · Additive toxicity and increased risk of adverse neurological effects · major

모니터링

Heartworm status prior to initiation of therapy
Fecal egg count reduction testing (FECRT) in horses (target >95% reduction to monitor for resistance)
Signs of neurotoxicity, especially in herding breeds or animals with low body fat
Heartworm status (antigen/microfilariae testing) prior to initiating preventative therapy
Resolution of clinical signs of parasitic infection
Application site for erythema or pruritus

과용량

Moxidectin generally has a wide margin of safety when administered at labeled doses. * **Dogs**: Dosages up to 300X (1120 mcg/kg) demonstrated little to no effects in normal dogs. However, in dogs with the **ABCB1 (MDR1) mutant genotype**, toxicity can be seen at doses as low as 90 mcg/kg. * **Clinical Signs of Toxicity**: Dysorexia, hypersalivation, mydriasis, fasciculations, ataxia, tremors, seizures, vomiting, hyperesthesia, and recumbency/coma. * **Treatment**: Supportive care. **Intravenous fat emulsion (IVFE)** has been successfully used to treat toxicity associated with macrocyclic lactones due to their highly lipid-soluble nature.

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