[The bioavailability of midodrin and alpha-2,5-dimethoxyphenyl-beta-aminoethanol hydrochloride].
The pharmacokinetics of midodrin (alpha-2,5-dimethoxyphenyl-beta-glycinamidoethanol hydrochloride, ST 1085) and its main metabolite ST 1059 (alpha-2,5-dimethoxyphenyl-beta-aminoethanol hydrochloride) have been investigated in 12 male healthy volunteers. 2.5 mg midodrin hydrochloride were applied intravenously, as drinking solution or as tablet (Gutron) according to a randomized cross-over design. Plasma and urine samples collected up to 24 h after application were analyzed by high-performance liquid chromatography with fluorescence detection. The mean maximum concentration in plasma for midodrin was ca. 10 ng/ml 20-30 min after oral administration, for ST 1059 ca. 5 ng/ml after 1 h. Midodrin was eliminated with a terminal half-life of 0.5 h. The half-life of ST 1059 was determined to be 3 h. The mean area under the plasma-level vs. time curve (AUC) of ST 1059 after administration of 2.5 mg midodrin i.v. was 28.7 ng X h/ml, and as drinking solution or as tablet 25.7 and 25.6 ng X h/ml, respectively. The data of 10 volunteers could be used for the calculations of the bioavailability of ST 1059 by the AUC. Assuming an interval of equivalence of 0.75-1.25 because of the relatively small number of volunteers, the three galenical formulations are considered to be equivalent.
D000284:Administration, Oral; D000316:Adrenergic alpha-Agonists / Q000008:administration & dosage / Q000097:blood / Q000378:metabolism*; D000328:Adult; D001682:Biological Availability; D002851:Chromatography, High Pressure Liquid; D004983:Ethanolamines / Q000378:metabolism*; D006801:Humans; D007275:Injections, Intravenous; D007700:Kinetics; D008297:Male; D008879:Midodrine / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000097:blood / Q000378:metabolism*
D000316:Adrenergic alpha-Agonists; D004983:Ethanolamines; C006146:ST 1059; D008879:Midodrine
Untersuchungen zur Bioverfügbarkeit von Midodrin und alpha-2,5-Dimethoxyphenyl-beta-aminoethanol-hydrochlorid.