The influence of thiopentone and alfathesin on succinylcholine-induced fasciculations and myalgias.

Thiopentone doses corresponding to 5.238 mg x kg-1, that is 2UD95 (UD95:unconsciousness dose 95) inhibit the intensity of succinylcholine-induced fasciculations compared with UD95. Alfathesin doses corresponding to 0.570 mg x kg-1, also 2UD95 (calculated as alphaxalone at a concentration of 9 mg/ml in alfathesin), do not have any greater effect on the degree of fasciculations compared to UD95. Furthermore, neither induction agent influences the incidence, distribution and duration of succinylcholine-induced myalgias. The inhibition of the degree of fasciculations caused by thiopentone is believed to be a consequence of a postsynaptic depressant effect of thiopentone at the neuromuscular junction. The evaluation of the degree of succinylcholine-induced fasciculations must take into consideration the dose of thiopentone administered at induction of anaesthesia.