米氮平
米氮平是一種非典型四環類抗憂鬱藥，在獸醫學中主要被廣泛用作犬貓的強效**食慾促進劑**和**止吐藥**。 * **臨床要點**：對於患有慢性腎病 (CKD)、鬱血性心衰竭、胃腸道疾病、肝病或腫瘤的病患特別有益，能同時改善噁心與食慾不振。 * 可安全地與其他止吐藥物併用，以治療頑固性嘔吐或化療引起的噁心嘔吐 (CINV)。 * 主要限制劑量的副作用為嗜睡，但在貓咪身上常觀察到矛盾的興奮現象（如異常鳴叫、變得過度親人）。 > **重要提示**：應始終使用最低有效劑量以減少鎮靜副作用。犬隻每日劑量不應超過 30 毫克，因為較高劑量反而會失去促進食慾的效果。
作用機制: Mirtazapine has a complex, multi-receptor pharmacological profile (often classified as a NaSSA - Noradrenergic and Specific Serotonergic Antidepressant): * **Central pre-synaptic α2-adrenergic receptors**: Antagonism blocks the negative feedback loop → **increases Norepinephrine (NE)** release → stimulates appetite via other α-receptors. * **5-HT3 receptors**: Potent antagonism in the Chemoreceptor Trigger Zone (CRTZ) and GI tract → provides robust **anti-nausea and antiemetic** effects. * **5-HT2 receptors**: Antagonism contributes to its anxiolytic profile. * **H1 (Histamine) receptors**: Potent antagonism → produces prominent **sedative effects**. * **Peripheral α1-adrenergic & Muscarinic receptors**: Moderate antagonism → may cause occasional orthostatic hypotension and mild anticholinergic effects.
各物種劑量
- As an appetite stimulant and/or antiemetic · 3.75 mg (¼ of a 15 mg tablet) · PO · q72h (every 3 days)
- As an appetite stimulant and/or antiemetic · 3 mg per cat · PO · q72h (every 3 days)
- As an appetite stimulant and/or antiemetic · 3-4 mg per cat · PO · q72h (every 3 days)
- Appetite stimulation · 1.9 mg/cat · PO · q48h · Can double dose if needed or increase frequency to q24h but not both.
- As an appetite stimulant and/or antiemetic · 0.6 mg/kg · PO · q24h · Not to exceed 30 mg per day for appetite stimulation
- As an appetite stimulant and/or antiemetic · >75 lb. = 15 mg PO q12h or 30 mg PO q24h (once daily) · PO · q12h or q24h
- Appetite stimulation / Management of social fears · 1.1-1.3 mg/kg · PO · q24h · Anecdotal use for social fears.
劑量為合格獸醫專業人員的臨床參考。請務必對照最新藥品仿單及個別病患確認。
給藥途徑
禁忌症
- Hypersensitivity to mirtazapine
- Use of monoamine oxidase inhibitors (MAOIs, e.g., selegiline) within the past 14 days
- Pre-existing haematological disease
不良反應
- Drowsiness/sedation
- Vocalization (especially in cats)
- Increased affection (cats)
- Hypotension
- Tachycardia
- Sedation (common and can be profound)
- Increased vocalization (especially in cats)
- Altered behavior and increased interaction with others
- Blood dyscrasias (reported in humans)
藥物相互作用
- CLONIDINE · Mirtazapine may cause increases in blood pressure
- DIAZEPAM (and other benzodiazepines) · Minimal effects on mirtazapine blood levels, but may cause additive impairment of motor skills
- FLUVOXAMINE · May cause increased serum concentrations of mirtazapine
- LINEZOLID · Increased risk for serotonin syndrome
- SELEGILINE, AMITRAZ · Increased risk for serotonin syndrome; MAO inhibitors considered contraindicated with mirtazapine
- TRAMADOL · Increased risk for serotonin syndrome
- Other behaviour-modifying drugs (e.g., SSRIs, MAOIs) · Increased risk of serotonin syndrome · major
監測
- Increased appetite
- Decreased episodes of vomiting
- Weight gain
- Adverse effects (sedation, vocalization, tachycardia)
- Appetite and body weight
- Behavioral changes (sedation, vocalization)
- Complete blood count (due to human risk of blood dyscrasias)
- Hepatic and renal function parameters
過量
Ingestion of upwards of 10-fold to 30-fold the therapeutic dose in humans exhibits minimal toxicity requiring no acute intervention other than observation. > **Treatment**: Despite the wide safety margin, standard overdose protocols (including the administration of **activated charcoal**) and monitoring are recommended in acute overdose situations.
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。