Influence of concentration and injection volume on the bioavailability of subcutaneous growth hormone: comparison of administration by ordinary syringe and by injection pen.
In order to study whether the bioavailability of subcutaneously injected growth hormone (GH) is dependent on the concentration/volume injected, the relative GH bioavailability was evaluated in 14 GH-deficient patients. In a cross-over study the patients received, in random order two separate subcutaneous GH injections (Norditropin) 4 IU administered by means of an ordinary syringe (4 IU ml) and an injection pen with cartridge (Nordiject 24) (12 IU/ml). Blood samples were drawn over a 14 hr period and assayed for serum concentrations of GH and IGF-I. The mean value (+/- S.D.) of the relative absorption fraction (Fpen/sy) was 1.09 +/- 0.39. Mean values of Cmax were 8.6 ng/ml +/- 4.8 and 8.3 ng/ml +/- 7.5 for syringe and pen respectively. Corresponding values for Tmax were 311 min. +/- 131 for syringe and 309 min. +/- 104 for pen. Although a considerable interindividual variation was seen, the relative absorption fraction did not differ significantly from 1 (2 P = 0.78). Further there was no significant difference in neither Cmax (2 P = 0.39) nor Tmax (2 P = 0.55). IGF-I serum profiles tended to be higher following syringe compared to pen injection (2 P = 0.054). On the basis of this study we conclude that in this dosage regimen. GH bioavailability following pen injection equals that of injection by syringe (i.e. no effect of a three fold increase/decrease in GH concentration/volume respectively).
Blok
G J
GJ
Department of Endocrinology, Free University Hospital, Amsterdam, The Netherlands.
van der Veen
E A
EA
Susgaard
S
S
Larsen
F
F
D000328:Adult; D001682:Biological Availability; D005260:Female; D013006:Growth Hormone / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D006801:Humans; D007277:Injections, Jet / Q000295:instrumentation; D007279:Injections, Subcutaneous / Q000295:instrumentation; D008297:Male; D008875:Middle Aged
D013006:Growth Hormone