納洛酮
解毒劑；鴉片類拮抗劑
**納洛酮 (Naloxone)** 是一種純鴉片類拮抗劑，在獸醫學中主要用於逆轉鴉片類促效劑的作用（如呼吸抑制、鎮靜和煩躁不安）。它是鴉片類藥物過量時的救命解毒劑。 除了主要用途外，目前也在研究將其用於治療各種類型的休克（敗血性、低血容性、心因性），以及透過阻斷內源性腦內啡來抑制追尾等自殘行為。 **臨床要點：** 納洛酮本身沒有鎮痛作用。當用於逆轉鴉片類藥物引起的呼吸抑制時，它會同時逆轉鴉片類藥物的鎮痛效果，可能導致疼痛突然恢復並引發兒茶酚胺釋放。
作用機制: Naloxone acts as a competitive antagonist at opioid receptors. It binds primarily to the **mu (μ)** receptor, but also has affinity for **kappa (κ)** and **sigma (σ)** receptors. By occupying these receptors without activating them, it displaces opioid agonists → **rapid reversal of opioid-induced respiratory and CNS depression**. At very high doses, naloxone may exhibit additional pharmacologic activity, including **GABA antagonism** and the ability to increase dopamine levels.
各物種劑量
Cats
- Opioid reversal · 0.01-0.02 mg/kg · IM, IV, or SC · As needed
- Neonatal opioid reversal (following caesarian sections) · 1 drop of naloxone (0.4 mg/mL from a 1-mL syringe) · Sublingual · As needed · Administered under the tongue.
- Adjunctive treatment of hyperthermia · 0.01 mg/kg · IM or SC · Once · Used in cats with body temperatures exceeding 41.1°C (106°F) following anesthesia; temperature returned to normal in <30 minutes.
- Opioid overdose / reversal · 0.01-0.02 mg/kg · IV · prn · Short duration (30-40 min) · Repeated doses may be required for longer-acting opioids.
- Opioid overdose / reversal · 0.04 mg/kg · IM/SC/intratracheal · prn · Short duration
- Prolonged opioid antagonism · 0.02 mg/kg/h · IV · CRI · As needed · Administered as a continuous rate infusion if a longer duration of opioid antagonism is required.
Horses
- Opioid reversal · 0.01-0.022 mg/kg · IV · As needed · To reverse sedative and excitatory effects of narcotic agonists. Note: ARCI UCGFS Class 3 Drug.
- Limit increases in locomotor activity secondary to narcotic agonists · 0.01 mg/kg · IV · As needed
- Treatment of opioid gastrointestinal tract dysfunction · 10-50 micrograms/kg · IV · As needed · Will induce movement and passage of contents.
SmallMammals
- Opioid reversal in rodents · 0.01-0.1 mg/kg · SC or IP · As needed
- Opioid reversal in rabbits · 0.005-0.1 mg/kg · IM or IV · As needed
- Opioid reversal in hamsters, gerbils, mice, rats, guinea pigs, chinchillas · 0.01-0.1 mg/kg · SC, IP · As needed
Dogs
- Opioid reversal · 0.01-0.02 mg/kg · IM, IV, or SC · As needed
- Opioid reversal · 0.04 mg/kg · IV, IM or SC · As needed
- Dysphoria associated with post-surgical opioids · 4 micrograms/kg diluted to 10 mL and given in 1-mL increments every minute · IV · Titrated to effect · Used if patient is clearly dysphoric or returns to whining state shortly after opioid administration.
- Neonatal opioid reversal (following caesarian sections) · 1 drop of naloxone (0.4 mg/mL from a 1-mL syringe) · Sublingual · As needed · Administered under the tongue; repeat doses can be sent home with owner if longer acting opioids are involved.
- Adjunctive treatment of pulseless electrical activity (PEA) in CPCR · 0.02-0.04 mg/kg · IV · As needed · May be effective in augmenting cardiac output by blocking endogenous endorphins or exogenous narcotics.
- Opioid overdose / reversal · 0.01-0.02 mg/kg · IV · prn · Short duration (30-40 min) · Repeated doses may be required for longer-acting opioids.
- Opioid overdose / reversal · 0.04 mg/kg · IM/SC/intratracheal · prn · Short duration
- Prolonged opioid antagonism · 0.02 mg/kg/h · IV · CRI · As needed · Administered as a continuous rate infusion if a longer duration of opioid antagonism is required.
劑量為持牌獸醫專業人員的臨床參考。請務必對照最新藥品說明書及個別病患確認。
給藥途徑
IVIMSCSublingualIntratracheal
禁忌症
- Hypersensitivity to naloxone
- Indiscriminate use in animals that have undergone major surgery or trauma (due to severe pain from analgesia reversal)
不良反應
- Reversal of analgesia (return of pain)
- Acute withdrawal syndrome in opioid-dependent patients
- CNS excitement (especially if used in meperidine overdose)
- Seizures (at very high doses, likely secondary to GABA antagonism)
- Acute severe discomfort or pain (due to sudden loss of analgesia)
- Antanalgesic effects in opioid-naïve subjects
- Transient elevation of unconsciousness (at low doses)
藥物相互作用
- Opioid partial-agonists (butorphanol, pentazocine, nalbuphine) · Naloxone may antagonize the effects of these agents (respiratory depression, analgesia). It should not be relied upon to treat respiratory depression caused by buprenorphine.
- Clonidine · Naloxone may reduce the hypotensive and bradycardic effects of clonidine; potentially useful for clonidine overdoses.
- Yohimbine · Naloxone may increase the CNS effects of yohimbine (anxiety, tremors, nausea, palpitations) and increase plasma cortisol levels.
- Opioid Agonists (e.g., Morphine, Methadone, Fentanyl) · Naloxone reverses the analgesic, sedative, and respiratory depressant effects of opioid agonists. · major
- Buprenorphine · Buprenorphine binds tightly to opioid receptors; naloxone may not fully reverse its effects or may require much higher doses. · moderate
監測
- Respiratory rate and depth
- CNS function (level of sedation/arousal)
- Pain associated with opiate reversal
- Respiratory rate and effort
- Level of consciousness / sedation score
- Pain score (monitor for acute pain upon reversal)
- Heart rate and blood pressure
過量
Naloxone is considered a very safe agent with a very wide margin of safety. However, massive overdoses have initiated seizures in a few patients, which is theorized to be secondary to GABA antagonism.
VetSheet 藥物參考供持牌獸醫專業人員作臨床決策輔助之用,不能取代專業判斷或廠方最新藥品說明書。