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Pharmacokinetics of recombinant human erythropoietin in children with renal failure
J H Evans1, J T Brocklebank, C J Bowmer
1Department of Paediatrics and Child Health, St James's University Hospital, Leeds, UK.
Insights
Pharmacokinetics of recombinant human erythropoietin (rHuEpo) in children with kidney failure show poor bioavailability via subcutaneous and intraperitoneal routes. Children absorb rHuEpo better but clear it faster than adults.
Area of Science:
- Pharmacology
- Nephrology
- Pediatrics
Background:
- Recombinant human erythropoietin (rHuEpo) is crucial for treating anemia in end-stage renal failure.
- Understanding rHuEpo pharmacokinetics in pediatric populations is essential for optimizing treatment.
Purpose of the Study:
- To investigate the single-dose pharmacokinetics of rHuEpo in children (9-16 years) with end-stage renal failure.
- To compare rHuEpo absorption and disposition via intravenous (i.v.), subcutaneous (s.c.), and intraperitoneal (i.p.) routes in this population.
Main Methods:
- Single-dose administration of rHuEpo (40 units/kg) via i.v., s.c., and i.p. routes.
- Serum rHuEpo concentrations were measured over time.
- Pharmacokinetic parameters including half-life (t1/2), clearance, volume of distribution, and fraction absorbed were calculated.
Main Results:
- Intravenous rHuEpo had a short half-life (5.6 h).
- Subcutaneous administration showed a longer half-life (21.1 h) but poor bioavailability (0.40 absorbed fraction).
- Intraperitoneal administration also resulted in poor bioavailability (0.17 absorbed fraction) and a half-life of 9.5 h.
- Children demonstrated faster rHuEpo clearance compared to adults, despite better absorption via s.c. routes.
Conclusions:
- rHuEpo disposition is absorption-rate-limited for s.c. and i.p. routes in children.
- Bioavailability of rHuEpo is poor via extravascular routes in pediatric patients.
- Pediatric patients exhibit distinct rHuEpo pharmacokinetics compared to adults, requiring tailored dosing strategies.
Abstract:
The single-dose pharmacokinetics of recombinant human erythropoietin (rHuEpo; 40 units/kg1) were investigated in children (9-16 years) with end-stage renal failure. After an intravenous (i.v.) dose, serum rHuEpo concentrations declined in a monoexponential manner with a mean half-life (t1/2) of 5.6 +/- 3 h (+/- SEM; n = 9). Serum clearance and the apparent volume of distribution were estimated to be 10.1 +/- 0.9 ml h-1 kg-1 and 79.5 +/- 5.0 ml kg-1 (n = 9) respectively. Subcutaneous (s.c.) delivery resulted in serum values that peaked at 10 h, and thereafter concentrations declined slowly with a t1/2 of 21.1 +/- 4.5 h (n = 9). Serum rHuEpo concentrations were maximal at 14 h after i.p. administration and the t1/2 was 9.5 +/- 1.0 h (n = 3). The mean fraction absorbed of SC rHuEpo was 0.40 whereas after i.p. administration this fraction was only 0.17. These results show that after both s.c. and i.p. delivery, disposition of the hormone is rate-limited by absorption, and bioavailability for these extravascular routes is poor. In addition, comparison of the results with those available for adults indicates that rHuEpo is better absorbed but more rapidly cleared in children.