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The relation between pharmacokinetics and endocrine effects of buserelin implants in patients with mastalgia
Author(s) -
Klijn Jan G. M.,
Geel Bert,
Jong Frank H.,
Sandow Jurgen,
Krauss Birgit
Publication year - 1991
Publication title -
clinical endocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.055
H-Index - 147
eISSN - 1365-2265
pISSN - 0300-0664
DOI - 10.1111/j.1365-2265.1991.tb03763.x
Subject(s) - buserelin , endocrinology , medicine , creatinine , urinary system , pharmacokinetics , renal function , excretion , urology , agonist , receptor
Summary Six patients with mastalgia were treated with polylactide/ glycolide SO: 50 implants containing 6 6 mg buserelin once every 4 weeks, to study the relationship between buserelin pharmacokinetics and suppression of pituitary‐ovarian function. On the first treatment day there was an initial rise in plasma and urinary buserelin levels followed by a rapid fall during the next 2 days. After a plateau phase (60–80 μg/g creatinine) urinary buserelin/creatinine ratios decreased slowly to a mean value of 25 μg/g creatinine 4 weeks after Implantation. Plasma oestradiol concentrations dropped to castrate values within 2 weeks of treatment reaching a mean concentration of 17 pmol/l compared to 27 pmol/l (P<0.01) determined In 680 postmenopausal control women. After the last implant injection urinary buserelin/creatinine ratios remained relatively high (> 5 μg/g creatinine) during more than 8 weeks followed by an exponential decrease (half‐life of buserelin release: 15 days) to undetectable buserelin levels at 16–22 weeks after the last implantation. A rise of suppressed plasma oestradiol concentrations to above castrate levels was found 15–20 weeks after the last buserelin Implantation, at a time when urinary buserelin excretion had decreased below 0.2 μg/g creatinine. It Is concluded that after initial suppression of pituitary‐ovarian function only very low concentrations of buserelin are needed to maintain suppression of ovarian activity by using slow release preparations.