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Effect of metrifonate on neuromuscular transmission
Abstract:
The least detectable effect of acute cholinesterase inhibition (produced by edrophonium) in a normal subject is described. It consists of repetitive activity following the muscle response to a single nerve stimulus. Repetitive activity does not follow a second response at an interval of 30 msec. or 80 msec. There is no change in amplitude of the response to a single stimulus; nor to a second stimulus with the smallest dose of edrophonium. With higher doses of edrophonium the amplitude of the second response is reduced. 55 children were studied during treatment of urinary schistosomiasis with metrifonate (3 doses at 2 weekly intervals). No change in evoked muscle action potential amplitude attributable to treatment was detected. 3 children developed some repetitive activity 6 hours after their third dose, when erythrocyte cholinesterase inhibition was approximately 50%.
Insights
Acute cholinesterase inhibition from edrophonium causes muscle repetitive activity. This effect was also observed in children treated with metrifonate for schistosomiasis, indicating potential neuromuscular side effects.
Area of Science:
- Neuroscience
- Pharmacology
- Clinical Medicine
Background:
- Cholinesterase inhibitors are used in various medical conditions.
- Understanding their least detectable effects is crucial for patient safety.
- Edrophonium and metrifonate are examples of cholinesterase inhibitors with distinct clinical applications.
Purpose of the Study:
- To describe the earliest detectable neuromuscular effect of acute cholinesterase inhibition.
- To investigate the effects of metrifonate treatment on neuromuscular function in children with schistosomiasis.
Main Methods:
- Single nerve stimulation and recording of muscle action potentials were used to assess neuromuscular function.
- Edrophonium was administered to normal subjects to determine dose-dependent effects.
- Erythrocyte cholinesterase inhibition levels were monitored in children treated with metrifonate.
Main Results:
- Acute cholinesterase inhibition with edrophonium produced repetitive muscle activity following a single nerve stimulus.
- This repetitive activity was not observed at short intervals (30 or 80 msec) between stimuli.
- No significant changes in evoked muscle action potential amplitude were detected in children treated with metrifonate, although 3 developed repetitive activity at high cholinesterase inhibition levels.
Conclusions:
- Repetitive muscle activity is the least detectable effect of acute cholinesterase inhibition.
- Metrifonate treatment for schistosomiasis can lead to cholinesterase inhibition and potentially cause neuromuscular side effects like repetitive activity.