[Differences in the effectiveness of levothyroxine preparations].
Three proprietary preparations of L-thyroxine were tested for their bioequivalence in a cross-over trial. Comparing the two most commonly prescribed preparations, during administration of preparation B (Euthyrox) serum concentrations of basal thyrotropin (TSH) was significantly higher than with preparation A (L-Thyroxin Henning) in both subgroups and in the cross-over calculation, as well as after stimulation with thyrotropin-releasing hormone (TRH) in one of the subgroups. During administration of a third preparation, C (Levothyroxine, enos), serum concentrations of total thyroxine (T4) and free thyroxine (fT4) were significantly lower than with preparation A, while basal and TRH-stimulated TSH levels were in all measurements highly significantly higher. Although there was the tendency for preparation B to be inferior, a greater effectiveness of preparation A could not be statistically proven for all data. But a markedly reduced bio-availability or effectiveness was demonstrated with respect to preparation C.
Wenzel
K W
KW
Klinikum Charlottenburg, Freie Universität, Berlin.
Mehrländer
U
U
D000328:Adult; D000368:Aged; D002986:Clinical Trials as Topic; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011897:Random Allocation; D013810:Therapeutic Equivalency; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood / Q000493:pharmacokinetics*
D013972:Thyrotropin; D013974:Thyroxine
Wirksamkeitsunterschiede von Levothyroxin-Präparaten.