펜토바르비탈

바르비투르산계 마취제 / 진정제 / 항경련제

**펜토바르비탈(Pentobarbital)**은 수의학에서 주로 전신 마취, 화학적 보정 및 난치성 뇌전증 지속상태 관리에 사용되는 단기 작용형 옥시바르비투르산계 약물입니다. 과거에는 전신 마취제로 널리 사용되었으나, 치료 지수가 좁고 심폐 억제 작용이 강해 현재는 더 안전하고 용량 조절이 용이한 약물(예: 프로포폴 또는 알팍살론)로 대부분 대체되었습니다. **임상 요점:** * **뇌전증 지속상태:** 난치성 발작 환자를 '바르비투르산 혼수' 상태로 유도하는 데 자주 사용됩니다. 그러나 표준 용량에서는 진정한 항경련 특성이 거의 없는 전신 마취제로 작용하여, 발작의 신체적 증상은 멈추게 하지만 뇌의 기저 발작 활동은 중단시키지 못할 수 있습니다. * **호흡 지원:** 펜토바르비탈로 치료받는 환자는 심각한 호흡 억제로 인해 일반적으로 기계적 환기 및 중환자실 모니터링이 필요합니다. * **안락사:** 훨씬 높은 용량에서 펜토바르비탈은 대부분의 동물용 안락사 용액의 주요 활성 성분입니다. * **효소 유도:** 장기 사용 시 간의 사이토크롬 P450 효소를 강력하게 유도하여 병용하는 많은 약물의 대사를 촉진합니다.

작용 기전: Pentobarbital exerts its profound central nervous system (CNS) depressant effects by interacting with the inhibitory neurotransmitter system. * **GABA_A Receptor Modulation:** Binds to the barbiturate site on the **GABA_A receptor** → increases the *duration* of chloride channel opening → enhances chloride influx → hyperpolarization of the postsynaptic neuronal membrane. * **Glutamate Inhibition:** At higher anesthetic doses, it also depresses the actions of the excitatory neurotransmitter glutamate via **AMPA receptors**. * **Result:** Dose-dependent CNS depression ranging from mild sedation to general anesthesia, coma, and fatal respiratory depression.

동물 종별 용량

Cats

For chemical restraint for ventilatory support · 1-3 mg/kg/hour · IV · CRI · Switch to shorter acting drug like propofol ~12 hours prior to weaning. Adjunctive drugs: Midazolam 0.3-0.5 mg/kg/hr; Medetomidine 0.3-1 mcg/kg/hr (caution with medetomidine).
As a sedative · 2-4 mg/kg · IV · single dose
As a sedative · 2-4 mg/kg · PO · q6h
For status epilepticus · 5-15 mg/kg to effect · IV · single dose
For status epilepticus · 3-15 mg/kg SLOWLY to effect · IV · single dose · Goal is heavy sedation, not surgical planes of anesthesia. May need to repeat in 4-8 hours.
For anesthesia · 25 mg/kg · IV · single dose · An additional 10 mg/kg IV may be given if initial dose is inadequate.
Euthanasia · 80 mg/kg in debilitated animals, up to 120-160 mg/kg in younger and fitter animals · IV · once · single dose · Rapid IV injection. Premedication recommended to prevent narcotic excitement.

Swine

General · 30 mg/kg to effect · IV · single dose
As an anesthetic · 15-30 mg/kg · IV · single dose

Sheep

As an anesthetic · 20-30 mg/kg · IV · single dose

투여 경로

IVPOIPITIC

금기

Severe hepatic impairment
Severe respiratory depression or airway obstruction
Porphyria
Hypovolemia or severe cardiovascular instability (relative contraindication)
Intramuscular (IM) administration (painful and slow to act)
Use of euthanasia-specific solutions for seizure control or anesthesia

이상반응

Profound respiratory depression (apnea)
Depression of myocardial metabolism
Vasodilation and decreased venous return
Hypotension and decreased cardiac perfusion
Poikilothermia (hypothermia)
Decreased urinary output
Seizure-like movements or excitement during recovery from anesthesia
Excitement and injury during induction/recovery in large animals (especially horses)
Narcotic excitement (if not premedicated)
Agonal gasping (reflexive, not a sign of pain)
Muscle twitching
Vocalization (rare, usually associated with excitement phase)

약물 상호작용

Oral Anticoagulants (Warfarin) · Decreased effect by lowering serum concentration (due to hepatic enzyme induction)
Beta-blockers · Decreased effect by lowering serum concentration
Chloramphenicol · Decreased effect by lowering serum concentration
Clonazepam · Decreased effect by lowering serum concentration
Corticosteroids · Decreased effect by lowering serum concentration
Cyclosporine · Decreased effect by lowering serum concentration
Doxorubicin · Decreased effect by lowering serum concentration
Doxycycline · Decreased effect (may persist for weeks after barbiturate is discontinued)
Estrogens · Decreased effect by lowering serum concentration
Griseofulvin · Decreased effect by lowering serum concentration
Methadone · Decreased effect by lowering serum concentration
Metronidazole · Decreased effect by lowering serum concentration
Quinidine · Decreased effect by lowering serum concentration

모니터링

Levels of consciousness and/or seizure control
Respiratory rate, rhythm, and depth (capnography and pulse oximetry highly recommended)
Cardiac signs (heart rate, blood pressure, ECG)
Body temperature (monitor for poikilothermia)
Routine blood counts and liver function tests (if used chronically)
Absence of heartbeat (auscultation)
Absence of respiration
Loss of corneal reflex
Pupillary dilation

과용량

**Overdose** of pentobarbital leads to profound central nervous system depression, progressing rapidly to coma, severe respiratory depression (apnea), cardiovascular collapse, and death. * **Treatment:** There is no specific reversal agent for barbiturates. Treatment is entirely supportive. * **Interventions:** Immediate intubation and mechanical ventilation are required. Intravenous fluids and vasopressors (e.g., dopamine) should be administered to support blood pressure and cardiac output. Maintain body temperature to prevent severe hypothermia.

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