| Abstract: | AIMS: The aim of this open, randomised, crossover, parallel-group study was to compare the pharmacokinetics and neutrophil responses of lenograstim when administered subcutaneously (s.c.) and intravenously (i.v.). METHODS: A total of 27 healthy male volunteers was recruited. Lenograstim doses (0.5, 2, 5, or 10 microg kg(-1)) were administered s.c. or i.v. once-daily for 5 days, and then, after a 10-day washout period, vice versa for a further 5 days. Lenograstim concentrations and absolute neutrophil counts (ANCs) were measured predosing and postdosing on days 1 and 5. RESULTS: Maximum serum concentrations of lenograstim were higher following i.v. dosing (mean 5.2-185.5 vs 0.7-30.0 ng ml(-1) after s.c. dosing on day 1) and attained sooner (median 0.5-0.8 vs 4.7-8.7 h on day 1). However, apparent elimination half-lives of lenograstim were longer following s.c. dosing (mean 2.3-3.3 vs 0.8-1.2 h after i.v. dosing on days 1 and 5). ANCs increased in a dose-dependent manner with both routes of lenograstim, but more prolonged rises and higher ANC peaks were attained following s.c. doses. ANCs peaked on day 6 following 5 microg kg(-1) s.c. doses (mean peak=26.3x10(9) cells l(-1)), but on day 2 after 5 microg kg(-1) i.v. doses (mean peak = 12.4 x 10(9) cells l(-1)). Irrespective of route, the most common adverse events were headaches and back/spine pain; at doses of up to 5 microg kg(-1) these were mild and generally well tolerated. CONCLUSIONS: While supporting the use of both s.c. and i.v. administered lenograstim to treat neutropenia, these results demonstrate that neutrophil responses are more sustained and prolonged with the s.c. route. |
