Abstract
Theophylline half-life (HL) doubles between childhood and adulthood. Effects of pubertal changes on HL was studied to investigate dose changes required in adolescence.
Seventy asthmatics taking theophylline chronically were studied: in 48 patients, HL was determined from 3 serum levels (8, 10, 12 hrs after dose) and in 22, HL, volume of distribution (Vda) and clearance were computed from 21 timed levels over 24 hours. Age (8-18), Tanner stage (I-V), sex, height (121-182 cm), weight (23-83 kg) and skin fold thicknesses (3.6-36.3 mm) were recorded. Growth variables (height & weight velocity & lean body mass) were derived from anthropometric measurements. Stepwise multiple regression analysis was performed with HL as dependent variable. Half-life was significantly related (p<0.01) to developmental stage (Tanner r=0.42, and age r=0.33) and body size (height r=0.39, LBM r=0.33, weight r=0.31). LBM (kg/kg) calculated by Lohman equation and Vda (1/kg) were related (r=0.59; p<.01). Best equations for HL contained 2 variables and were: (for sex, ♂ = 0 and ♀ = 1).
HL = 4.57 + 1.31 sex + 0.0687 height (r=0.48)
HL - 3.54 + 1.32 sex + 0.0725 LBM (r=0.43)
Thus, half-life is related to age, sex and body size during adolescence. The dose and dosing interval must be monitored closely during adolescence because metabolic -rate (HL) and body composition (Vda) both change rapidly during the teenage years.
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Hein, K., Dell, R., Reuben, N. et al. INFLUENCE OF PUBERTAL DEVELOPMENT ON THEOPHYLLINE KINETICS. Pediatr Res 21 (Suppl 4), 175 (1987). https://doi.org/10.1203/00006450-198704010-00051
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DOI: https://doi.org/10.1203/00006450-198704010-00051