Эдрофоний

Description

Edrophonium is a short-acting, reversible acetylcholinesterase inhibitor, a quaternary ammonium compound. Competitively blocks the enzyme mainly in the area of ​​the neuromuscular synapse, increasing the concentration of acetylcholine in the synaptic cleft. It acts quickly (the effect develops within 30–60 seconds after administration) and does not last long (on average about 10 minutes).

Basic Attributes

• CAS No.: 312-48-1
• Chemical formula: C10H16NO
• Molecular weight: 166.244
• Exact weight: 166.123
• UNII: 70FP3JLY7N
• DSSTox ID: DTXSID4046943
• ATC code (Anatomical-therapeutic-chemical classification): V - Various
• PSA specifications: 20.2
• XLogP3: 1.8

Physico-chemical characteristics

• Appearance: liquid
• Melting point: 162–163 °C
• Solubility in water: 4.86 × 10⁻² g/l

Mechanism of action

Reversibly inhibits acetylcholinesterase, slowing down the hydrolysis of acetylcholine at the neuromuscular junction. An increase in acetylcholine concentrations temporarily enhances neuromuscular transmission. The low PSA value (20.2) and moderate lipophilicity (XLogP3 1.8) ensure rapid penetration to the site of action and equally rapid elimination, which explains the short duration of the effect.

Scope of application

Historically, Tensilon was used in the diagnostic test for the differential diagnosis of myasthenia gravis, an autoimmune neuromuscular disease in which antibodies destroy postsynaptic nicotinic acetylcholine receptors. Administration of edrophonium provides short-term relief of muscle weakness, which has been used to distinguish between myasthenic and cholinergic crises, as well as Lambert-Eaton syndrome.

Current status

Since 2018, it has been withdrawn from circulation in the United States and a number of other countries due to the lack of sensitivity and specificity of the Tensilon test and the associated risks of side effects with intravenous administration of an anticholinesterase drug.

Storage and transportation

Store in the original tightly closed container in a cool, dry place, away from heat and open flame. Follow the general rules for handling pharmaceutical substances that are sensitive to moisture.

Differential diagnosis

The value of the Tensilon test was the speed of response: in true myasthenia gravis, an injection of edrophonium within a minute reduced ptosis, diplopia and weakness of the limbs, while in cholinergic crisis (overdose of other anticholinesterase drugs), the symptoms, on the contrary, intensified, since excess acetylcholine was already saturating the synapse. In Lambert-Eaton syndrome, where the defect is localized presynaptically, the response to edrophonium was usually weaker and less pronounced than in myasthenia gravis. Such differentiation was especially important in mechanically ventilated patients, when the clinical picture of weakness could be caused by different causes requiring opposing treatment.