Journal of applied physiology
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Clinical experience and laboratory studies suggest that neonates are more sensitive than adults to the ventilatory depressant effects of morphine. Similar sensitivity has been cited, but not demonstrated, for fentanyl. To examine this issue, we determined ventilatory pharmacodynamics of morphine and fentanyl in 28 dogs aged 2-35 days. ⋯ For fentanyl, there was a small maturational increase in C50 and no change in keo. We conclude that there are marked maturational changes in the ventilatory depressant effects of morphine resulting from maturational changes in sensitivity rather than in equilibration. Maturational changes in the ventilatory effects of fentanyl are much smaller in magnitude than those for morphine.