美索巴莫
**美索巴莫 (Methocarbamol)** 是一種中樞性骨骼肌鬆弛劑，在結構上與癒創木酚甘油醚 (guaifenesin) 相關。在獸醫學中廣泛用於治療骨骼肌的急性發炎和創傷，以及控制嚴重的肌肉痙攣和震顫。 **臨床要點：** * 高度有效且經常作為挽救生命的干預措施，用於治療**貓的百滅寧 (permethrin) 中毒**和狗的**震顫性黴菌毒素**（例如發霉食物）中毒。 * 提供口服和注射兩種劑型。 * 注射劑型含有聚乙二醇 (PEG) 300，可能會加重原有的腎臟病理變化；因此，對於患有嚴重腎臟疾病的病患，應謹慎使用或避免使用靜脈注射劑型。 * 不會直接放鬆收縮的骨骼肌，而是透過中樞神經系統抑制來發揮作用。
作用機制: The exact mechanism of action of methocarbamol is not fully understood, but it is known to act centrally rather than peripherally. * **Central CNS Depression:** It is believed to cause skeletal muscle relaxation by general central nervous system depression, likely depressing polysynaptic reflexes in the **internuncial neurons** of the spinal cord. * **No Peripheral Action:** It has **no direct relaxant effects** on striated muscle, nerve fibers, or the motor endplate. * **Secondary Effects:** Produces a secondary sedative effect due to its generalized CNS depressant properties.
各物種劑量
- Relief of moderate conditions · 44 mg/kg IV · IV · As directed · Administer half the estimated dose rapidly, then wait until animal starts to relax and continue administration to effect.
- Controlling severe effects of strychnine and tetanus · 55-220 mg/kg IV · IV · As directed · Do not exceed 330 mg/kg/day. Administer half the estimated dose rapidly, then wait until animal starts to relax and continue administration to effect.
- General muscle relaxation (Tablets) · Initially, 132 mg/kg/day PO divided q8h-q12h, then 61-132 mg/kg divided q8-12h · PO · q8h-q12h · Discontinue if no response in 5 days
- Adjunctive treatment (control of seizures/muscle tremors) of permethrin toxicity · initially administered at 50-150 mg/kg IV · IV · As directed · First half is given IV slowly over approximately 5-10 minutes and the second half of the dose being given as needed to effect. The dose can be repeated up to a maximum of 330 mg/kg/day; in severely affected cases, the total daily dose can be calculated and given over 24 hours as a constant rate infusion.
- General muscle spasms, tetanus, toxicities · 20-45 mg/kg · PO · q8h · As needed · Very high doses may be required for tetanus. Recommended not to exceed 330 mg/kg. Limited literature in cats.
- Moderate conditions · 4.4-22 mg/kg IV to effect · IV · As directed · ARCI UCGFS Class 4 Drug
- Severe conditions · 22-55 mg/kg IV · IV · As directed
- General muscle relaxation · 15-25 mg/kg IV by slow infusion · IV · As directed
給藥途徑
禁忌症
- Food-producing animals
- Renal disease (injectable formulation only, due to PEG 300 vehicle)
- Known hypersensitivity to methocarbamol
- Subcutaneous (SC) administration
- No specific contraindications available, but use with caution in renal or hepatic impairment.
不良反應
- Sedation
- Salivation
- Emesis
- Lethargy
- Weakness
- Ataxia
藥物相互作用
- CNS Depressants (e.g., opioids, benzodiazepines, barbiturates) · Additive CNS depression may occur when given concurrently.
- Pyridostigmine · May cause severe weakness (reported in a human patient with myasthenia gravis).
- Other CNS depressants · Additive CNS depression · moderate
監測
- Level of muscle relaxation
- Degree of sedation
- Respiratory rate and effort (especially with high IV doses or concurrent CNS depressants)
- Degree of muscle relaxation
- CNS depression/sedation levels
- Renal and hepatic function (if prolonged use)
過量
**Signs of Toxicity:** Overdosage is generally characterized by profound CNS depressant effects, including loss of righting reflex and prostration. Excessive doses in dogs and cats may manifest as emesis, salivation, severe weakness, and ataxia. **Management:** * **Decontamination:** If the overdose occurred recently via oral administration, emptying the gut (e.g., emesis induction or gastric lavage) may be indicated. **Do not induce emesis** if the patient's continued consciousness and airway protection are not assured. * **Supportive Care:** Treat other clinical signs supportively if severe. Monitor respiratory and cardiovascular function closely.
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