Disposition of pulse dose methylprednisolone in adult and paediatric patients with the nephrotic syndrome.

The disposition of a large pulse-dose of methylprednisolone was examined in paediatric and adult patients with the nephrotic syndrome. Plasma concentrations and urinary excretion rates were measured by high performance liquid chromatography. Most of the dose was metabolized, as indicated by urinary recovery of less than 10 percent of the dose. There was only slight age-dependence of the plasma clearance and volume of distribution of the steroid, although the T1/2 and mean transit time were shorter in younger patients. The pharmacokinetic parameters of the large doses (12-20 mg/kg) were similar to low dose (0.5-1 mg/kg) data from asthmatic patients. The limited variability of the pharmacokinetics of methylprednisolone suggests that tissue sensitivity may be a more important indicator of drug dosage needs in nephrotic syndrome.