Amitraz
Amitraz is a formamidine acaricide and insecticide used primarily in veterinary medicine for the treatment of generalized demodicosis in dogs, as well as for flea and tick control. * **Clinical Pearl:** Amitraz is highly effective against *Demodex* mites but requires strict adherence to safety protocols due to its potent alpha-2 adrenergic agonist effects in mammals. * It is available as a liquid concentrate for dilution (e.g., Mitaban) and in impregnated collars (e.g., Preventic). * **Toxicity Warning:** It is highly toxic to cats, rabbits, and horses. Use in these species is generally avoided or done strictly extra-label with extreme caution.
Mecanismo: Acts as a **monoamine oxidase (MAO) inhibitor** in susceptible mites → alters neurotransmitter breakdown → CNS toxicity and death. Additionally, acts as an **alpha-2 adrenergic agonist** in mammals → inhibits insulin release → transient hyperglycemia and sedation. Also inhibits **prostaglandin synthesis**.
Dosificación por especie
- Generalized demodicosis (Labeled Protocol) · 250 ppm (one 10.6 mL bottle in 2 gallons of warm water) · topical · q14d · 3-6 treatments (or until 30 days past two negative skin scrapings) · Apply to entire animal and air dry. DO NOT rinse or towel dry.
- Generalized demodicosis (Extra-label Protocol 1) · 250 ppm, 500 ppm, or 1000 ppm · topical · q7d · Until 30 days past two negative skin scrapings · Step up concentration if lower doses fail. Increased risk of toxicity at higher doses.
- Generalized demodicosis (Extra-label Protocol 2) · 0.125% solution (1 mL of 12.5% Taktic in 100 mL water) · topical · q24h · Until 30 days past two negative skin scrapings · Rub onto one-half of the dog's body and alternate sides daily.
- Otic demodicosis · 1 mL of 12.5% Taktic in 8.5 mL mineral oil · topical · q3-7d · Until resolved · Discontinue if irritation develops.
- Generalized mite infestations (canine demodicosis, sarcoptic acariasis and cheyletiellosis) · Diluted as a dip, left on the coat · topical · As directed (typically weekly or bi-weekly depending on specific product label) · Until clinical and microscopic resolution · Clipping long-haired coats will improve penetration. Animals should not be bathed or allowed to swim for 48 hours after application.
- Follicular demodicosis (Demodex cati) · 0.0125% (125 ppm) · topical · q7-14d · Until resolved · Extra-label. Monitor very closely for side effects. Use E-collar until dry.
- Surface demodicosis (Demodex gatoi) · 0.0125% (125 ppm) · topical · q7d · 12 weeks · Extra-label. Monitor very closely for side effects. Use E-collar until dry.
Vías de administración
Contraindicaciones
- Cats and rabbits (highly toxic, though extra-label protocols exist)
- Chihuahuas and toy breeds (use with extreme caution)
- Puppies less than 4 months of age
- Dogs with deep pyodermas and draining tracts (treat infection first)
- Brittle diabetic patients
- Pregnant or nursing animals
Efectos adversos
- Transient sedation (up to 72 hours)
- Ataxia
- Bradycardia
- Vomiting and diarrhea
- Hypothermia
- Transient hyperglycemia
- Pruritus, erythema, and edema at application site
- Seizures (rare)
Interacciones farmacológicas
- Corticosteroids · Immunosuppression can worsen demodicosis; concomitant use is contraindicated.
- Selegiline · Concurrent use of MAO inhibitors increases risk of toxicity.
- Amitriptyline · Concurrent use with tricyclic antidepressants is not recommended.
- Clomipramine · Concurrent use with tricyclic antidepressants is not recommended.
- Alpha-2 agonist sedatives (e.g., dexmedetomidine, xylazine) · Additive or synergistic CNS depression and cardiovascular effects (bradycardia). · major
- Other ectoparasiticides · Potential for increased toxicity. · moderate
Monitoreo
- Resolution of clinical signs (negative skin scrapings)
- Blood glucose levels (especially in diabetic patients)
- Heart rate and body temperature
- Signs of excessive sedation or CNS depression
Sobredosis
Toxicity can be significant, especially if amitraz-containing collars are ingested. * **Signs:** Ataxia, severe CNS depression, bradycardia, hypothermia, and marked hyperglycemia. * **Treatment:** Emesis (if asymptomatic), endoscopic retrieval of ingested collars, activated charcoal, and cathartics. * **Antidotes:** **Yohimbine** (0.11-0.2 mg/kg IV) or **Atipamezole** can effectively reverse the alpha-2 adrenergic mediated signs (sedation, bradycardia, hyperglycemia). Repeated doses may be necessary due to the short half-life of the reversal agents.
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