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Population pharmacokinetic/pharmacodynamic (PK/PD) modelling of the hypothalamic-pituitary-gonadal axis following treatment with GnRH analogues
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
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2007 (English)In: British Journal of Clinical Pharmacology, ISSN 0306-5251, E-ISSN 1365-2125, Vol. 63, no 6, 648-664 p.Article in journal (Refereed) Published
Abstract [en]

Aims:To develop a population pharmacokinetic/pharmacodynamic (PK/PD) model of the hypothalamic–pituitary–gonadal (HPG) axis describing the changes in luteinizing hormone (LH) and testosterone concentrations following treatment with the gonadotropin-releasing hormone (GnRH) agonist triptorelin and the GnRH receptor blocker degarelix.MethodsFifty-eight healthy subjects received single subcutaneous or intramuscular injections of 3.75 mg of triptorelin and 170 prostate cancer patients received multiple subcutaneous doses of degarelix of between 120 and 320 mg. All subjects were pooled for the population PK/PD data analysis. A systematic population PK/PD model-building framework using stochastic differential equations was applied to the data to identify nonlinear dynamic dependencies and to deconvolve the functional feedback interactions of the HPG axis.ResultsIn our final PK/PD model of the HPG axis, the half-life of LH was estimated to be 1.3 h and that of testosterone 7.69 h, which corresponds well with literature values. The estimated potency of LH with respect to testosterone secretion was 5.18 IU l−1, with a maximal stimulation of 77.5 times basal testosterone production. The estimated maximal triptorelin stimulation of the basal LH pool release was 1330 times above basal concentrations, with a potency of 0.047 ng ml−1. The LH pool release was decreased by a maximum of 94.2% by degarelix with an estimated potency of 1.49 ng ml−1.ConclusionsOur model of the HPG axis was able to account for the different dynamic responses observed after administration of both GnRH agonists and GnRH receptor blockers, suggesting that the model adequately characterizes the underlying physiology of the endocrine system.

Place, publisher, year, edition, pages
2007. Vol. 63, no 6, 648-664 p.
Keyword [en]
GnRH agonist triptorelin, GnRH receptor blocker degarelix, Hypothalamic-pituitary-gonadal axis, NONMEM, Population PK/PD modelling, Systematic PK/PD model building framework
National Category
Pharmaceutical Sciences
URN: urn:nbn:se:uu:diva-13730DOI: 10.1111/j.1365-2125.2006.02820.xISI: 000246576800003PubMedID: 17096678OAI: oai:DiVA.org:uu-13730DiVA: diva2:41500
Available from: 2008-01-25 Created: 2008-01-25 Last updated: 2011-02-01Bibliographically approved

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Karlsson, Mats O.
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