Median Effective Doses (ed50) of Halothane in Adults and Children

Median effective doses of halothane (ED50), determined in 73 pediatric subjects and 31 adults grouped according to age, were: 1.20 per cent at 0 to 6 months; 1.16 per cent at 6 to 24 months; 1.07 per cent at 24 to 48 months; and 0.9 per cent in adults. The dose-response curves for all groups did not deviate significantly from parallelism. Halothane was 1.28 and 1.12 times more potent in producing anesthesia in adults than in the 0-to-6-months and 6-to-24-months group. Potency in the 24-to-48-months group did not differ significantly from potency in adults or in younger children. In contrast, taking hypotension as a measure of circulatory effect, halothane is a less potent cardiovascular depressant in adults than in young children.