펜타닐

아편양 진통제 (뮤 수용체 작용제)

**펜타닐(Fentanyl)**은 매우 강력한 합성 페닐피페리딘 유도체로, 수의학에서 중등도에서 중증의 통증 관리에 광범위하게 사용되는 **2급 아편양 진통제**입니다. **주요 약리학적 특징:** * **역가:** 모르핀보다 약 75~100배 더 강력합니다. * **지용성:** 펜타닐은 지용성이 매우 높아 혈액-뇌 장벽을 빠르게 통과하며(정맥 주사 시 작용 발현이 매우 빠름), **경피 투여(패치)**에 매우 적합합니다. * **지속 시간:** 단회 정맥 주사 시, 뇌에서 다른 조직으로 빠르게 재분포되기 때문에 작용 시간이 매우 짧습니다(15~30분). 따라서 지속적인 진통을 위해 **지속적 정맥 주입(CRI)** 또는 **경피 패치**를 통해 투여하는 것이 가장 일반적입니다. **임상 적용:** * 수술 후 통증의 보조적 조절. * 중증의 만성 통증, 둔통 또는 비특이적 광범위 통증(예: 암, 췌장염, 대동맥 혈전색전증) 관리. * 수술 전후에 사용하여 흡입 마취제의 최소 폐포 농도(MAC)를 크게 낮추어 심혈관계 기능이 저하된 환자에게 안정성을 제공합니다. > **임상 요점:** 경피 패치는 매우 편리하지만 개체 간 흡수율의 차이가 매우 큽니다. 펜타닐 패치에 의존할 때는 항상 '구조(rescue)'용 주사 진통제를 준비해 두어야 합니다.

작용 기전: Fentanyl is a highly selective **full agonist at the mu-opioid receptor (MOR)**. **Mechanism Pathway:** 1. **Receptor Binding:** Fentanyl binds to presynaptic and postsynaptic mu-receptors primarily located in the central nervous system (limbic system, spinal cord, thalamus, midbrain) and peripheral tissues. 2. **G-Protein Activation:** Binding activates inhibitory G-proteins (Gi/Go). 3. **Cellular Effects:** * Inhibits **adenylate cyclase**, decreasing intracellular cAMP. * Promotes the opening of **inward-rectifying potassium (K+) channels**, leading to neuronal hyperpolarization. * Inhibits the opening of **voltage-gated calcium (Ca2+) channels** on presynaptic nerve terminals. 4. **Analgesia:** This cascade profoundly inhibits the release of excitatory, nociceptive neurotransmitters (such as **Substance P** and **glutamate**) and decreases the excitability of postsynaptic neurons, effectively blocking pain transmission.

동물 종별 용량

Cats

Perioperative pain · 2-3 micrograms/kg IV plus 2-3 micrograms/kg/hour IV infusion · IV/CRI · Continuous · Perioperative
Pain management · 1-3 micrograms/kg IV, followed by a CRI at 1-4 micrograms/kg/hr · IV/CRI · Continuous · Loading dose followed by CRI
Surgical analgesia · CRI at 10-30 micrograms/kg/hr · CRI · Continuous · Intraoperative
Analgesia · 2-4 micrograms/kg/hour · CRI · Continuous
Induction · 0.001-0.002 mg/kg IV · IV · Single dose
MAC reduction during general anesthesia · 10-20 micrograms/kg/hr CRI · CRI · Continuous · Intraoperative
Severe to excruciating pain in the emergent patient · Fentanyl at 1050 micrograms/kg, administered IV titrated to effect; use the effective dose as an hourly CRI. · IV/CRI · Titrated to effect · Note: '1050' appears exactly as written in source text, likely a typo for 10-50.
Epidural for pain control · 0.004 mg/kg (4 micrograms/kg), diluted 0.2 mL with preservative-free saline or local anesthetic. · Epidural · Single dose · 1/2 hour · Onset in less than 10 minutes
Maintenance analgesia/heavy sedation in critically ill hypotensive animals · fentanyl at 0.5-0.8 micrograms/kg/minute (equivalent to 30-50 micrograms/kg/hr). · CRI · Continuous · Used in addition to a local line block. May combine with midazolam.
Transdermal Analgesia · 25 mcg/hr or 12.5 mcg/hr · Transdermal · q120h · Up to 5 days · Apply 6-24 hours prior to need. 12 mg patches are available for very small cats.

투여 경로

IVCRITransdermalEpiduralTopicalPO

금기

Known hypersensitivity to fentanyl or patch adhesive
Conditions where additional respiratory or CNS depression would be deleterious
No specific contraindications available in the monograph (use with caution in patients with respiratory compromise)

이상반응

Dose-related respiratory depression
CNS depression (sedation)
Circulatory depression (bradycardia)
Dysphoria or agitation (especially in cats)
Urine retention
Constipation
Contact dermatitis/rash at patch site
Altered thermoregulation (hypothermia or hyperthermia)
Respiratory depression
Severe bradycardia
Asystole (with rapid IV injection)
Reduction in heart rate

약물 상호작용

Azole Antifungals (ketoconazole, itraconazole, fluconazole) · May inhibit fentanyl metabolism, increasing risk of toxicity
CNS Depressants (other) · Additive CNS and respiratory depressant effects
Diuretics · Opiates may decrease diuretic efficacy in congestive heart failure patients
Macrolide Antibiotics (erythromycin, clarithromycin) · May inhibit fentanyl metabolism
Monoamine Oxidase Inhibitors (amitraz, selegiline) · Severe and unpredictable opiate potentiation; generally not recommended within 14 days of MAOI use
Skeletal Muscle Relaxants · Fentanyl may enhance neuromuscular blockade
Nitrous Oxide · High fentanyl doses combined with nitrous oxide may cause cardiovascular depression
Phenobarbital, Phenytoin · May increase the metabolism of fentanyl, reducing its efficacy
Rifampin · May increase the metabolism of fentanyl
Tricyclic Antidepressants (clomipramine, amitriptyline) · Fentanyl may exacerbate the effects of tricyclic antidepressants
Warfarin · Opiates may potentiate anticoagulant activity
Other anaesthetic drugs · Reduces the dose requirement for other anaesthetic agents · major

모니터링

Analgesic efficacy (pain scoring)
Heart rate (monitor for bradycardia)
Respiratory rate and depth
Body temperature (monitor for fever which increases patch absorption)
Neurologic status (sedation, dysphoria)
Heart rate and rhythm (monitor for bradycardia)
Blood pressure
Adequacy of analgesia
Body temperature (avoid external heat on patches)

과용량

**Clinical Signs of Overdose:** Profound respiratory and/or CNS depression, cardiovascular collapse, bradycardia, hypothermia, tremors, neck rigidity, and seizures. Newborns are particularly susceptible. **Treatment:** * **Naloxone** is the specific reversal agent of choice for treating respiratory depression. * Because naloxone's duration of action is often shorter than fentanyl's, **repeated doses or a CRI of naloxone** may be required. * Patients must be closely monitored for re-narcotization. * Mechanical respiratory support should be instituted in cases of severe respiratory depression.

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