Abstract
The only report of neonatal T pharmacokinetics indicated half-life varied from 3.3-33 hours in 8 patients. The longest half-life occurred in an infant with a poor cardiovascular status. Adult dogs eliminate T by renal tubular base transport without detectable metabolism by a chemically non-specific assay. This transport system is saturable and immature in infants at birth thus placing infants at risk for limited T excretion. We have developed a chemically-specific microassay for T by gas chromatography-mass spectrometry and used it to study 12 T eliminations following pulse and infusion doses in 10 infants. T half-life varied from 1.5-29.6 hrs and showed a significant correlation with the logarithm of urine output from 0.40-2.35 ml/kg/hr (R=0.77, p<0.01). In 2 infants studied twice, the longer half-life occurred during lower urine output. In 2 infants who failed to void for 3-4 hrs after a T dose, concentrations measured every 30 min did not decrease until voiding resumed. This suggests that T is not significantly metabolized in infants and that decreased urine production prolongs T half-life exponentially. The variation in T half-life in these patients and those previously reported may be explained by variation in urine output. During oliguria, pulse doses of T may need to be decreased in frequency and infusion doses decreased in magnitude to avoid T accumulation and adverse effects.
Article PDF
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Ward, R., Kendig, J., Daniel, C. et al. RELATIONSHIP BETWEEN URINE OUTPUT AND TOLAZOLINE (T) HALF-LIFE. Pediatr Res 18 (Suppl 4), 162 (1984). https://doi.org/10.1203/00006450-198404001-00415
Issue Date:
DOI: https://doi.org/10.1203/00006450-198404001-00415