Repeated doses of suxamethonium in the myasthenic patient.

The neuromuscular block of successive doses of suxamethonium 100 mg, monitored by electromyography, was investigated in a myasthenic patient (class IIB), undergoing thymectomy. The results suggest that successive doses of suxamethonium in the myasthenic patient are followed by a progressive prolongation of the neuromuscular block. This may be attributed to rapid desensitisation of the myasthenic endplate receptors and the rapid development of phase II block, as evidence by a progressive decrease of the T4/T1 ratio.