부토르파놀

오피오이드 부분 효능제 / 진해제 / 진통제

**부토르파놀(Butorphanol)**은 다양한 동물 종의 수의학에서 널리 사용되는 합성 오피오이드 부분 효능제입니다. * **진통 작용**: 경도에서 중등도의 내장 통증에 대한 진통 효과를 제공합니다. "천장 효과(ceiling effect)"로 인해 고용량을 투여해도 진통 효과가 증가하지 않으므로 심한 통증(예: 주요 정형외과 수술)에는 적합하지 않습니다. * **진해 작용**: 개의 만성 비생산성 기침(예: 전염성 기관기관지염, 기관 허탈)을 억제하는 데 매우 효과적입니다. * **역전제**: 펜타닐, 메타돈, 모르핀과 같은 순수 뮤(mu) 효능제로 인한 심각한 호흡 및 중추신경계 억제를 역전시키면서도 카파(kappa) 수용체 매개 진통 효과를 어느 정도 유지하는 독특한 유용성이 있습니다. * **진정 작용**: 시너지 효과가 있는 진정 및 화학적 보정을 위해 알파-2 효능제(예: 덱스메데토미딘 또는 자일라진) 및 벤조디아제핀과 자주 병용됩니다. > **임상 요점**: 부토르파놀은 소동물에서 훌륭한 진해제 및 경미한 진정제이지만, 작용 시간이 매우 짧아(개의 경우 진통 작용이 보통 1시간 미만) 일차 진통제로서의 유용성은 제한적입니다. 반면, 말(예: 산통)에서는 매우 효과적이고 흔히 사용되는 내장 진통제입니다.

작용 기전: Butorphanol exerts its effects by interacting with specific opioid receptors in the central nervous system: * **Kappa (κ) and Sigma (σ) Agonist**: Activation of κ-receptors in the limbic system and spinal cord provides visceral analgesia and sedation. * **Mu (μ) Antagonist**: Competitively binds to and blocks μ-receptors. This antagonism is responsible for its ability to reverse pure μ-agonist drugs and is the reason for its analgesic "ceiling effect." * **Antitussive Mechanism**: Directly suppresses the **medullary cough center**, elevating the threshold to stimuli (like CO2) without depressing respiratory center sensitivity as profoundly as pure agonists. * **Cellular Pathway**: Binds to κ-receptors → inhibits adenylate cyclase → decreases intracellular cAMP → closes voltage-gated calcium channels and opens potassium channels → hyperpolarization and reduced neuronal excitability.

동물 종별 용량

Cats

As an analgesic · 0.1-0.5 mg/kg IV, IM, SQ · IV/IM/SC · PRN · Provides only mild to moderate analgesia; duration of sedative action 2-4 hours, but analgesic action may be 1 hour or less.
As a postoperative CRI · Loading dose of 0.1-0.2 mg/kg IV, then a CRI of 0.1-0.2 mg/kg/hr · IV · CRI · Usually in combination with ketamine (loading dose 0.1 mg/kg IV, CRI 0.4 mg/kg/hr).
As an epidural analgesic · 0.25 mg/kg diluted with preservative-free saline (0.2 mL) or local anesthetic epidurally · Epidural · Once · 2-4 hours · Onset of action less than 30 minutes.
As reversal agent for mu-agonist opiates · 0.05-0.1 mg/kg IV · IV · Once · Does not completely reverse analgesic effects.
In combination as an immobilizing agent (short procedures) · butorphanol 0.2 mg/kg; medetomidine 0.001-0.015 mg/kg; midazolam 0.05-0.2 mg/kg · IM · Once · For difficult cats and short procedures.
In combination as an immobilizing agent (more sedation) · butorphanol 0.2 mg/kg; medetomidine 0.015-0.02 mg/kg; midazolam 0.05-0.2 mg/kg; add ketamine 1-5 mg/kg when insufficient sedation · IM · Once

Ferrets

As a sedative/analgesic · Butorphanol alone 0.05-0.1 mg/kg IM, SC. Butorphanol/Xylazine: Butorphanol 0.2 mg/kg + Xylazine 2 mg/kg IM · IM/SC · Once
For injectable anesthesia · Butorphanol 0.1 mg/kg, Ketamine 5 mg/kg, medetomidine 80 micrograms/kg. Combine in one syringe and give IM. · IM · Once · May need to supplement with isoflurane (0.5-1.5%) for abdominal surgery.

투여 경로

POIMIVSCEpiduralCRI (Constant Rate Infusion)

금기

Known hypersensitivity to butorphanol
Lower respiratory tract conditions with copious mucous production (suppressing cough prevents clearance)
Caution in patients with head trauma, increased CSF pressure, or severe CNS dysfunction (e.g., coma)
Caution in severe liver disease, renal insufficiency, hypothyroidism, or Addison's disease
Caution in dogs with heartworm disease (safety not established)

이상반응

Sedation and ataxia
Anorexia or diarrhea (rare in small animals)
Respiratory depression (mild compared to pure agonists)
CNS excitement, head tossing, and increased ambulation (especially in horses at high doses or rapid IV administration)
Decreased gastrointestinal motility and potential ileus (horses)
Nystagmus, salivation, seizures, and hyperthermia (at massive overdoses in horses)

약물 상호작용

Other CNS Depressants (anesthetics, antihistamines, phenothiazines, barbiturates, tranquilizers) · May cause increased CNS or respiratory depression; dosage may need to be decreased.
Erythromycin · Could potentially decrease the metabolism of butorphanol, prolonging its effects.
Fentanyl (and other pure opiate agonists) · Butorphanol may antagonize analgesic effects, but will also reverse sedative and respiratory depressant effects.
Pancuronium · May cause increased conjunctival changes when used concurrently.
Theophylline · Could potentially decrease the metabolism of butorphanol.
Anaesthetic agents · Reduces the doses of other drugs required for induction and maintenance of anaesthesia · moderate
Full mu-opioid agonists (e.g., methadone, fentanyl) · Addition of butorphanol will reduce analgesia produced from the full mu agonist; combination is not recommended for analgesia · major
Acepromazine · Synergistic sedation · moderate
Alpha-2 agonists · Synergistic sedation and analgesia · moderate
Full mu-agonist opioids (e.g., methadone, fentanyl) · Butorphanol's mu-antagonist properties may block or partially reverse the analgesic effects of full mu-agonists. Higher doses of full mu-agonists may be required. · major

모니터링

Analgesic and/or antitussive efficacy
Respiratory rate and depth
Appetite and bowel function
CNS effects (sedation vs. excitement)

과용량

Acute life-threatening overdoses are unlikely (LD50 in dogs is 50 mg/kg). However, because veterinary injection comes in two highly different strengths (0.5 mg/mL and 10 mg/mL), inadvertent overdoses can occur in small animals. **Clinical Signs**: CNS effects (profound sedation or excitement), cardiovascular changes, and respiratory depression. **Treatment**: * Administer **intravenous naloxone** immediately to reverse opioid effects. * Provide supportive measures: IV fluids, oxygen therapy, vasopressors, and mechanical ventilation if required. * If seizures occur and persist, use **diazepam** for control.

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