Neostigmine
**Neostigmine** is a reversible acetylcholinesterase inhibitor used primarily in veterinary medicine for the diagnosis and management of **myasthenia gravis**, as well as to antagonize the effects of non-depolarizing neuromuscular blocking agents. Because of its polar structure, it has poor penetration into the central nervous system (CNS). > **CLINICAL WARNING:** Administration can precipitate a life-threatening **cholinergic crisis**. It is highly recommended to use a combined formulation with glycopyrronium or have atropine drawn up and ready for immediate intravenous administration to control severe muscarinic side effects (e.g., severe bradycardia, asystole, bronchoconstriction). **Clinical Pearl:** Compared to edrophonium (Tensilon), neostigmine has a slower onset of action but a significantly longer duration of effect (30 minutes to 2 hours), making it useful for diagnostic exercise testing in dogs with brief collapse episodes.
กลไกการออกฤทธิ์: Neostigmine acts as a reversible inhibitor of the enzyme **acetylcholinesterase** at the neuromuscular junction (NMJ) and autonomic synapses. Inhibition of **acetylcholinesterase** → Decreased breakdown of **acetylcholine (ACh)** → Accumulation of ACh in the synaptic cleft → Prolonged and enhanced stimulation of **nicotinic** and **muscarinic receptors** → Improved muscle contraction (in myasthenia gravis) and reversal of non-depolarizing neuromuscular blockade.
ขนาดยาตามชนิดสัตว์
- Diagnosis of myasthenia gravis / Antagonism of non-depolarizing neuromuscular block · 0.05 mg total dose (historical) · IV · Single dose · N/A · Historical dose; recent reports indicate this can cause cholinergic crisis. Recommended to use combined formulation with glycopyrronium. Pre-treat with atropine if using for MG diagnosis.
- Diagnosis of myasthenia gravis / Antagonism of non-depolarizing neuromuscular block · 0.05 mg total dose (historical) · IV · Single dose · N/A · Extrapolated from general text. Extreme caution due to risk of feline asthma exacerbation.
ขนาดยาเป็นข้อมูลอ้างอิงทางคลินิกสำหรับสัตวแพทย์ผู้มีใบอนุญาต โปรดตรวจสอบกับฉลากล่าสุดและผู้ป่วยแต่ละรายเสมอ
วิธีการให้ยา
ข้อห้ามใช้
- Mechanical gastrointestinal obstruction
- Mechanical urinary tract obstruction
- Peritonitis
อาการไม่พึงประสงค์
- Nausea and vomiting
- Increased salivation (ptyalism)
- Diarrhoea
- Muscle fasciculations and cramps
- Weakness and paralysis (with overdose)
- Severe bradyarrhythmias or asystole
- Miosis and nystagmus
- Hypotension
- Bronchoconstriction and increased bronchial secretions
อันตรกิริยาระหว่างยา
- Aminoglycosides · May antagonize the neuromuscular effects of neostigmine · moderate
- Clindamycin · May antagonize the neuromuscular effects of neostigmine · moderate
- Halogenated inhalational anaesthetics · May antagonize the neuromuscular effects of neostigmine · moderate
- Quinine and related compounds · May increase clinical severity of myasthenia gravis and reduce neostigmine effectiveness · moderate
- Beta-blockers · May reduce effectiveness in myasthenia gravis; concurrent use may result in severe bradycardia · major
- Suxamethonium · Neostigmine inhibits its metabolism, prolonging and enhancing its clinical effect (combined use not recommended) · major
- Non-depolarizing muscle relaxants · Neostigmine antagonizes their effect (therapeutic use) · major
- Atropine · Antagonizes the muscarinic effects of neostigmine (used therapeutically to manage side effects) · moderate
การติดตาม
- Heart rate and rhythm (ECG monitoring recommended during IV administration)
- Respiratory rate, effort, and airway patency
- Signs of cholinergic crisis (excessive salivation, urination, defecation, miosis)
- Muscle strength and fasciculations
การได้รับยาเกินขนาด
**Cholinergic Crisis** can occur with overdosage, presenting with both muscarinic and nicotinic effects (SLUDGE signs: Salivation, Lacrimation, Urination, Defecation, Gastrointestinal distress, Emesis), miosis, bradycardia, hypotension, muscle cramps, fasciculations, weakness, paralysis, bronchoconstriction, ataxia, seizures, and coma. **Management:** * **Maintenance of respiration** is the absolute priority. * Administer **Atropine** to control muscarinic signs (note: atropine does *not* antagonize nicotinic effects like muscle weakness and paralysis). * If muscle twitching is severe, control with small doses of a **competitive neuromuscular blocker**. * The cholinesterase reactivator **pralidoxime** can be used as an adjunct to atropine. * Provide intensive supportive care as required.
ข้อมูลอ้างอิงยาของ VetSheet มีไว้สำหรับสัตวแพทย์ผู้มีใบอนุญาตเพื่อช่วยในการตัดสินใจทางคลินิก ไม่ใช่สิ่งทดแทนการวินิจฉัยของผู้เชี่ยวชาญหรือฉลากล่าสุดของผู้ผลิต