Both postnatal and postmenstrual age contribute to the interindividual variability in tramadol glucuronidation in neonates

Besides PMA, there is an additional, independent impact of PNA since phenotypic glucuronidation activity is significantly lower in the first week of postnatal life. These findings should be taken into account in the assessment of compounds for whom glucuronidation is of pharmacokinetic, pharmacodynamic or toxicological relevance.