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At least 19 recordsLinked to original sources
PubMed1987

LRH agonist buserelin as a post-partum contraceptive: lack of biological activity of buserelin in breast milk.

To evaluate the possibility of using the LRH agonist buserelin as a contraceptive for lactating women we have investigated the passage of buserelin into breast milk and explored possible biological activity in the infant. Eleven mothers received 600 micrograms buserelin by nasal spray. Buserelin was measured by radioimmunoassay in the breast milk of these mothers, and values ranged from undetectable levels (less than 15 pg/ml) to 8800 pg/ml. The maximum amount of buserelin that an infant could ingest during an average feed would be 1-2 micrograms. In adult men ingestion of 600 micrograms buserelin dissolved in cows milk was without biological effect upon both serum and urinary levels of luteinizing hormone. There was no change in the levels of LH found in the urine of infants fed by women who had received 600 micrograms buserelin by nasal spray. We conclude that the small amount of buserelin passing into the breast milk of these volunteers was without biological activity when ingested by the infant.

Administration, Intranasal↗
PubMed1987

Metastatic cancer of the prostate managed with buserelin versus buserelin plus cyproterone acetate.

We recruited 71 previously untreated patients with metastatic prostatic carcinoma to 2 separate consecutive prospective phase 2 studies done by the same group of investigators according to the same protocols in which only the treatment regimens differed. Of the patients 58 were treated with the luteinizing hormone-releasing hormone analogue buserelin alone (0.4 mg. 3 times daily intranasally) and 13 were treated with buserelin combined with cyproterone acetate, a potent antiandrogen (50 mg. 3 times daily orally). The objective of the study was to investigate the efficacy, safety and tolerability of the medication used during at least 12 months by studying adequate endocrine parameters, the rate and duration of response, as well as the rate of progression and possible side effects. All endocrine parameters were studied in 1 laboratory. Modified response criteria of the National Prostatic Cancer Project were used. The endocrine studies showed an effective suppression of plasma testosterone to castration levels by buserelin after an initial increase during the first 2 weeks. Luteinizing hormone and follicle-stimulating hormones were lowered significantly and could not be re-stimulated by the intravenous application of luteinizing hormone-releasing hormone. There was no correlation of plasma testosterone with response and progression. However, a significant correlation existed between higher basal cortisol levels at entry, and after 3 and 6 months, and progression. Response is reported for all patients at the 12-month interval and did not seem to differ among treatment groups. The rate of progression after all patients had been treated for 1 year was 37.9 per cent in the buserelin group and 41 per cent in the buserelin plus cyproterone acetate group. Three early deaths occurred in the buserelin group. Except for impotence, only mild side effects were noted. Our study shows that treatment of metastatic prostatic cancer by means of the luteinizing-hormone-releasing hormone analogue buserelin is safe and effective. The results obtained are compatible with those obtained by castration. In our study a superiority of total androgen withdrawal over testicular suppression alone could not be shown.

Buserelin↗
PubMed1989

Administration of nasal Buserelin as compared with subcutaneous Buserelin implant for endometriosis.

One hundred infertile patients with laparoscopically confirmed ovarian endometriosis were treated with either intranasal (IN) Buserelin (Hoechst, AG, Frankfurt am Main, West Germany) (300 micrograms three times a day) or subcutaneous (SC) Buserelin implant (6.6 mg Buserelin). Serum estradiol was suppressed in the menopausal range in both groups, but the inhibition of the pituitary ovarian axis appeared more profound and consistent in the SC group than in the IN group. Laparoscopic findings proved that the SC Buserelin emerged superior to the IN Buserelin. Indeed, the score of endometriotic lesions and the ovarian cyst diameter were more reduced in the SC group than in the IN group. Moreover, the histologic study showed a lower incidence of active endometriosis and a lower mitotic index of ovarian endometrial epithelium in the SC group than in the IN group. In conclusion, the release of a gonadotropin-releasing hormone agonist by a biodegradable implant achieved better efficacy in reducing endometriotic lesions than the IN mode of administration.

Administration, Intranasal↗
PubMed1989

Serum concentration and urinary excretion of the luteinizing hormone-releasing hormone agonist buserelin in patients with endometriosis.

We studied the pharmacokinetics of iv and intranasally administered buserelin, a LHRH agonist peptide, in 14 women with endometriosis. Serum and urinary buserelin concentrations were determined by specific RIA (buserelin antiserum AS-639). Intact buserelin and the metabolites in urine were separated by reverse phase high performance liquid chromatography and measured by RIA. The mean serum buserelin concentrations were 101 +/- 33 (+/- SD) ng/mL 20 min and 1.12 +/- 0.12 ng/mL 360 min after its iv injection in 6 women, and the mean elimination half-life between 20 and 360 min was 51 min. In serum, intact buserelin was the main constituent (10 min, 90%; 120 min, 74%; 360 min, 52%), and the major metabolite was the buserelin-(5-9) pentapeptide (10 min, 0.6%; 120 min, 19%; 360 min, 12%). In the urine collected 0-1 h after buserelin administration, intact buserelin was 66% and the 5-9 pentapeptide was 28% of the total excretion. In the urine collected between 6-24 h after buserelin administration, intact buserelin accounted for 67% and the 5-9 pentapeptide for 32% of the total excretion. The urinary buserelin concentration was 1345 +/- 156 micrograms/g creatinine 1 h and 25 +/- 5 micrograms/g creatinine 6-24 h after buserelin administration. Serum LH, FSH, and estradiol concentrations increased acutely up to 10-fold above basal values; the mean peak LH, FSH, and estradiol values occurred at 180-240 min, 240 min, and 24 h, respectively. In therapeutic studies with buserelin nasal spray in 5 women, serum concentrations of 0.9-1.4 ng/mL were found 15 min after a single dose of 300 micrograms, intranasally, and the urinary excretion was 2.52-3.68 micrograms/24 h during daily administration of 3 doses of 300 micrograms at intervals of 8 h. These results confirm that buserelin is slowly inactivated and remains available to pituitary receptors for a prolonged period after its iv or intranasal administration.

Administration, Intranasal↗
PubMed1986

The prolonged action of the LHRH agonist buserelin (HOE 766) may be due to prolonged binding to the LHRH receptor.

Hemi-pituitary glands of ovariectomized rats were superfused for 4 h with either LHRH or the analog buserelin (HOE 766) at several concentrations, and thereafter with medium only for another 1.5 h. In a further experiment glands were exposed for 2.5 h to LHRH or buserelin at a single concentration (5 ng/ml) and subsequently for another 2.5 h to either the same agonist (LHRH or buserelin) alone (5 ng/ml), the agonist plus an LHRH-antagonist (ORG 30093, 1000 ng/ml), the LHRH- antagonist alone, or medium alone. LHRH and buserelin stimulated gonadotropin release equally well. After cessation of this stimulation, the gonadotropin release by the buserelin-treated pituitary glands and the glands, treated with the highest dose of LHRH (1000 ng/ml), continued, while the release by the glands, treated with the lower doses of LHRH, declined. The LHRH-antagonist completely blocked the release of LH, stimulated by buserelin or LHRH, as well as the prolonged activation of the release, caused by buserelin pre-treatment. In a superfusion experiment with pituitary cell aggregates of 14-day-old intact female rats, buserelin stimulated the release of LH much more effectively than LHRH itself. Moreover, the release caused by buserelin declined more slowly after cessation of the stimulation. Finally, in a pituitary cell monolayer culture the Kd's of LHRH, buserelin and the antagonist were determined as 4.7 X 10(-9) M, 2.4 X 10(-10) M and 4.6 X 10(-9) respectively. It was concluded that the estimates of the potencies of LHRH and buserelin depend on the choice of the test-system. It is suggested that the long duration of action of buserelin is at least partly due to prolonged binding to the LHRH-receptor.

Animals↗
PubMed1986

Pharmacokinetic characteristics of the gonadotropin-releasing hormone analog D-Ser(TBU)-6EA-10luteinizing hormone-releasing hormone (buserelin) after subcutaneous and intranasal administration in children with central precocious puberty.

A double antibody RIA was developed for the measurement of the long-acting GnRH agonist D-Ser(TBU)6EA10GnRH (buserelin). The antibody, raised in rabbits against a buserelin-hemocyanin conjugate, reacted with the intact molecule and also molecular fragments containing the C6-9 tetrapeptide sequence and permitted the measurement of buserelin activity in serum and urine. Natural GnRH, LH, and FSH did not cross-react in this assay system. The assay was applied to samples obtained from children receiving buserelin for the management of central precocious puberty either by once daily injection of 30 micrograms/kg or by nasal spray (in; 200 micrograms every 8 h). Urine and serum samples, chromatographed on Sephadex G-25, contained immunoreactive material corresponding closely in molecular size to [125I]buserelin. In unextracted serum samples taken at intervals after sc therapy in 11 girls, the peak immunoreactive buserelin levels of 52.2 +/- 14.8 ng/ml (mean +/- SEM) occurred at 30 min. The half-time of elimination was 74.9 +/- 36.9 min. Approximately 30% of the dose was detected in urine collected for 3 h after injection. Similar data were obtained in 3 normal adults given 10 micrograms/kg buserelin, iv. By contrast, after the administration of 200 micrograms buserelin by metered nasal spray, the mean peak serum concentration in 10 girls was 100-fold less (0.65 +/- 0.14 ng/ml), although the halftime of elimination was almost identical. Only 0.73% of the nasal dose was excreted by 3 h. Calculated relative bioavailability data indicated maximal nasal absorption of 6%. However, absorption after nasal administration varied greatly, and in 2 children, serum and urinary concentrations of buserelin after supervised administration were negligible. We conclude that in buserelin therapy, in the dose used in this study, does not represent optimal treatment for the initial management of patients with precocious puberty. The success of in therapy in sustaining initial effects of buserelin given by sc administration presumably reflects changes in receptor sensitivity induced by sc treatment.

Administration, Intranasal↗
PubMed1990

Buserelin. A review of its pharmacodynamic and pharmacokinetic properties, and clinical profile.

The gonadotrophin releasing hormone (GnRH) [luteinising hormone-releasing hormone (LHRH); gonadorelin] agonist buserelin is a promising new agent in the treatment of a variety of disorders in gynaecology and andrology, paediatrics and oncology. While a single dose of buserelin stimulates the release of pituitary gonadotrophins, multiple doses produce reversible pituitary desensitisation, and this specific blockade of gonadotrophin support to the gonads provides the basis for the drug's efficacy in conditions dependent on sex hormone secretion. Thus, buserelin provides comparable efficacy to orchidectomy or high dose estrogens in the treatment of hormone-sensitive prostate cancer and exhibits a lower incidence of adverse effects. During the early phase of treatment it may be particularly useful in combination with antiandrogens. Buserelin also appears promising in hormone-sensitive premenopausal breast cancer. Extensive studies have proven the value of buserelin in endometriosis, where it produces a transient remission with gradual recurrence of the disease on cessation of treatment. Surgical intervention is necessary in severe disease after buserelin-induced involution of the lesions. In patients with uterine leiomyoma, preliminary data suggest that buserelin may be beneficial in rendering surgery more conservative by reducing fibroid size, although it appears unlikely to preclude surgical intervention. The use of buserelin to induce a state of reversible hypogonadotrophism before administration of exogenous gonadotrophins is a promising strategy in the treatment of infertility associated with polycystic ovary syndrome and other conditions of infertility with underlying ovarian dysfunction; such a strategy also clearly enhances the efficiency of in vitro fertilisation programmes. Initial studies suggest its potential usefulness as a female contraceptive when administered intermittently in conjunction with a progestogen. Buserelin represents a first-line treatment of central precocious puberty. In endometriosis the adverse effect profile of buserelin is generally favourable, with hypoestrogenic effects such as hot flushes and vaginal dryness, and decreased libido, predominating. There is no apparent detrimental effect on lipid metabolism. The potential for adverse hypoestrogenic effects on bone mineral content with long term administration remains to be clarified. Thus, the GnRH agonist buserelin represents an advance in the treatment of a variety of gynaecological and andrological as well as paediatric and oncological conditions, infertility and other sex-hormone dependent conditions, with a low incidence of adverse treatment effects.

Animals↗
PubMed1989

A new way to induce oestrogen-deficiency osteopaenia in the rat: comparison of the effects of surgical ovariectomy and administration of the LHRH agonist buserelin on bone resorption and composition.

Prolonged administration of LHRH agonist suppresses pituitary gonadotrophin secretion, thereby lowering blood oestrogen. This study was undertaken to compare the osteopaenic effects of bilateral ovariectomy and chronic administration of the LHRH agonist, buserelin, in the rat. Four groups of animals which had their skeletons labelled with 45Ca were studied for 4 weeks. Group 1 underwent a sham-ovariectomy, group 2 were surgically ovariectomized, group 3 were given buserelin by daily s.c. injection and group 4 were given a continuous infusion of buserelin by osmotic minipump. Plasma concentrations of oestradiol were measured weekly. Bone resorption was assessed by measuring the urinary excretion of 45Ca and hydroxyproline and determining bone 45Ca content. Ovariectomy and buserelin treatments lowered blood oestradiol, increased biochemical indices of bone resorption and decreased femur and total body calcium and 45Ca values. The degree of oesteopaenia elicited by ovariectomy and buserelin treatment was similar. Bone responses to s.c. buserelin and to continuous buserelin infusion were alike. We attribute evidence of increases in bone resorption and induction of osteopaenia with buserelin treatment to hypo-oestrogenism. We have shown for the first time by bone analysis that buserelin induces osteopaenia as effectively as bilateral ovariectomy. This appears to be the first demonstration in the rat that long-term administration of LHRH agonist influences bone. Administration of buserelin provides a new way of inducing oestrogen-deficiency osteopaenia in the rat without removing the ovaries.

Animals↗
PubMed1990

Buserelin-mediated osteoporosis: effects of restoring estrogen on bone resorption and whole body calcium content in the rat.

In the rat, prolonged administration of the luteinizing, hormone-releasing hormone agonist buserelin (25 micrograms/kg body wt/day s.c.) lowers blood estradiol, raises bone resorption, and induces osteopenia. The present study was undertaken to determine whether withdrawal of buserelin normalizes blood estradiol, slows bone resorption, and corrects buserelin-mediated osteopenia. Four groups of female rats with 45Ca-labeled bones were studied: group 1A received 0.2 ml saline s.c. daily for 4 weeks; group 2A received 0.2 ml buserelin s.c. daily for 4 weeks; group 1B received 0.2 ml saline s.c. daily for 8 weeks; group 2B received 0.2 ml buserelin s.c. daily for 4 weeks followed by 0.2 ml saline s.c. daily for 4 weeks. Bone resorption was monitored by measuring urinary 45Ca and hydroxyproline. The rats in groups 1A and 2A were killed after 4 weeks and those in groups 1B and 2B after 8 weeks. The mineral contents of the femoral bones and the whole skeletons were measured. Buserelin lowered blood estradiol, elevated urinary 45Ca and urinary hydroxyproline, and lowered femur and total body calcium and 45Ca in group 2A vs. 1A (P less than 0.05). By contrast all these measurements became similar in groups 2B and 1B. Thus, osteopenia generated by a 4-week period of buserelin-mediated hypo-estrogenism is reversible by withdrawing buserelin for 4 weeks. Consequently, buserelin administration and withdrawal may be used to study effects of inducing and reversing estrogen-deficiency bone loss in the rat.

Animals↗
PubMed1992

Pharmacokinetics of the gonadotropin-releasing hormone agonist buserelin after injection of a slow-release preparation in normal men.

The pharmacokinetics of the gonadotropin-releasing hormone (GnRH) agonist buserelin (D-Ser(BUt)6-GnRH-(1-9) nonapeptide-ethylamide, Hoe 766, CAS 57982-77-1) after injection of a slow-release preparation was investigated in 16 healthy young male volunteers. Eight volunteers received a buserelin implant of 3.3 mg and 8 volunteers one of 6.6 mg by subcutaneous injection. In order to prevent androgen deficiency symptoms caused by the GnRH agonist all volunteers were injected with an initial loading dose of 400 mg of the androgen 19-nortestosterone hexyloxyphenylpropionate one week prior to the buserelin administration, followed by injections of 200 mg once every three weeks up to week 23. Maximal buserelin serum levels were measured two days after injection of the implant. Following a slow decrease in serum concentrations up to week 8, serum buserelin had disappeared by week 14 in the 3.3 mg group and by week 17 in the 6.6 mg group. The areas-under-the-serum-concentration-versus-time-curves (AUCs) for the 3.3 and 6.6 mg implants were 691 +/- 60 ng x h/ml and 1050 +/- 102 ng x h/ml, respectively (p less than 0.01). The mean residence times (MRTs) of buserelin after administration of 3.3 mg and 6.6 mg buserelin implant were 4.7 +/- 0.4 and 4.1 +/- 0.3 weeks, respectively (p greater than 0.05). Urinary excretion of buserelin showed a similar pharmacokinetic profile. However, urinary buserelin was still detectable at very low concentrations by the end of the study, i.e. 29 weeks after implant injection.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Pharmacokinetics and endocrine effects of the LHR analogue buserelin after subcutaneous implantation of a slow release preparation in prostatic cancer patients.

The pharmacokinetics and endocrine effects of the LHRH analogue buserelin [D-Ser(TBU)6-LHRH], released from biodegradable implants, were studied in 14 patients with stage C and D prostate cancer. Six patients received a subcutaneous implant of 3.3 mg buserelin monthly, and 8 patients received a subcutaneous implant of 6.6 mg buserelin every two months. Serum levels of buserelin decreased rapidly immediately after implantation. After 1-2 weeks a more gradual decline occurred, while in the two-monthly treated group a third phase of the elimination curve started after 5 weeks. Mean serum buserelin levels just before the next implantation in the two groups were not different. Urinary excretion of buserelin followed the same pattern. Serum LH levels in both groups became non-detectable 2 weeks after the first implant. This decrease of LH levels was accompanied by a suppression of serum testosterone to concentrations below 1 nmol/l (castration level). Side effects were not different from those observed with the intranasal application of buserelin. It is concluded that the subcutaneous application of buserelin is an easily administered form of treatment which has more profound and more reliable endocrine effects when compared with the intranasal administration of the drug. The greatest advantage of the new preparation is that the intervals between applications may be prolonged to at least 2 months.

Aged↗
PubMed1985

Radioimmunoassay of an analog of luteinizing hormone-releasing hormone, [D-Ser(tBu)]6des-Gly-NH2(10) ethylamide (Buserelin).

A sensitive and specific radioimmunoassay is described for plasma and urinary levels of [D-Ser(tBu)]6des-Gly-NH2(10) ethylamide (buserelin). No appreciable cross-reaction (less than 0.05%) was observed with LH-RH and its analogs other than buserelin fragments (1.6-45%). The sensitivity was 3 pg per tube. At buserelin concentrations of 125, 250 and 500 pg/ml, the intra- and inter-assay coefficients of variation were 7.9, 10.0 and 10.0%, and 19.0, 7.8 and 6.8% respectively. Recovery of buserelin added to plasma was quantitative (62.5 pg/ml, 101.6%; 125 pg/ml, 76.8% and 250 pg/ml, 63.4%). A dose of 5 micrograms buserelin injected subcutaneously into 5 normal male adults, reached a peak plasma level in 45 min (mean value 119.3 +/- 47.3 pg/ml) and remained detectable for at least 4 h. The half disappearance time was 118.8 +/- 26.0 min. Between 9 and 16% of the administered dose was excreted in the urine within 24 h. Buserelin could also be detected in the plasma after intranasal administration of doses of 150, 300 and 450 micrograms. There was a significant difference in the area under the curve (AUC) for plasma levels after subcutaneous injection of 5 micrograms and intranasal administration of 150 micrograms, but not between the AUC values after the three intranasal doses. These results indicate that this method for radioimmunoassay of buserelin is suitable for analyzing the pharmacokinetics and bioavailability of buserelin in man.

Administration, Intranasal↗
PubMed1991

Effect of chemotherapy with or without buserelin on serum hormone levels in premenopausal women with breast cancer.

Serial determinations of serum oestradiol (E2), follicle-stimulating hormone (FSH) and luteinising hormone (LH) were done to assess the effect of chemotherapy, with or without a gonadotropin-releasing hormone analogue, buserelin, on ovarian function in 147 premenopausal women treated for breast cancer. Cyclophosphamide, doxorubicin and 5-fluorouracil (CAF) plus buserelin was given to 81 women with metastatic disease, and 66 women were randomised to adjuvant cyclophosphamide, methotrexate and 5-fluorouracil (CMF) with buserelin or CMF alone. Baseline mean E2 of patients treated with cytostatics plus buserelin fell from premenopausal levels and remained low while patients were on study. E2 levels remained at premenopausal values in patients treated with CMF alone. Downregulation of FSH and LH occurred with cytostatics plus depot buserelin, but fluctuated with the nasal administration; on CMF alone, FSH and LH levels increased. Buserelin plus cytostatics more effectively caused ovarian ablation than cytostatic treatment alone. Depot buserelin was more effective than nasal buserelin.

Adult↗
PubMed1988

The antiandrogen anandron potentiates the castrating effect of the LH-RH agonist buserelin in the rat.

When buserelin (0.04-25 micrograms/kg/day), a potent LH-RH agonist, was administered s.c. daily for 15 days to male rats, prostate weight decreased after a transient increase in the first days of treatment but never as much as after orchidectomy, since testosterone secretion was never totally suppressed. The combination of the pure nonsteroid antiandrogen Anandron (20 mg/kg/day) with even low doses of buserelin led to an immediate decrease in prostate weight that was complete at 15 days. This could be explained (a) by an additivity of effects: inhibition by Anandron of the action of residual testosterone unsuppressed by buserelin on the prostate and prevention by buserelin of the rebound testosterone increase induced by Anandron: (b) by a potentiation by Anadron of the direct castrating effect of buserelin on the testis since testis weight and testosterone secretion were lowered to a greater extent by the combination than by buserelin alone. Anandron might increase the sensitivity of LH-RH receptors to LH-RH agonist in the testes, as has been shown in the pituitary. In contrast, the combination of the antiandrogenic steroid progestin, cyproterone acetate, with buserelin never potentiated the castrating effect of buserelin on testis weight and testosterone and only partially potentiated prostate atrophy. If such actions also exist in the human, the addition of Anandron to LH-RH agonist treatment would not only counter flare-up and adrenal androgen effects on the prostate but would also lower the doses of peptide or the time required for chemical castration.

Administration, Oral↗
PubMed1990

Prolonged treatment with the GnRH analogue buserelin does not affect alpha-subunit production by the pituitary gonadotroph.

Seven patients with metastatic prostatic cancer were treated with biodegradable implants of the GnRH analogue buserelin and six were treated with buserelin intranasally. After 4-24 weeks of treatment mean serum testosterone concentrations were significantly lower in the patients treated with implants than in those treated intranasally (0.7 vs 1.7 nmol/l respectively; P less than 0.01). Also, serum LH concentrations were significantly lower in the group treated with implants. Serum alpha-subunit concentrations were significantly higher than pretreatment values during buserelin treatment. However, the sum of the concentrations of alpha-subunit present either as free alpha-subunit or as a part of LH did not differ significantly from pre-treatment values after 8 weeks or more of buserelin treatment. During buserelin treatment serum LH concentrations measured by radioimmunoassay (RIA) were higher than those measured by immunoradiometric assay (IRMA). Cross-reactivity of alpha-subunit in the LH RIA accounted for many, but not all, of the observed discrepancies. We conclude that: (1) the principal long-term effect of prolonged buserelin administration on the pituitary gonadotroph is the suppression of LH beta production, while alpha-subunit production is not affected; (2) the serum concentrations of bioactive LH are better reflected by LH concentrations measured by IRMA than by those measured by RIA. (3) Subcutaneous application of biodegradable buserelin implants is more effective in suppressing serum LH and testosterone concentrations than intranasal buserelin application.

Buserelin↗
PubMed1991

The relation between pharmacokinetics and endocrine effects of buserelin implants in patients with mastalgia.

Six patients with mastalgia were treated with polylactide/glycolide 50:50 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 micrograms/g creatinine) urinary buserelin/creatinine ratios decreased slowly to a mean value of 25 micrograms/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 less than 0.01) determined in 680 postmenopausal control women. After the last implant injection urinary buserelin/creatinine ratios remained relatively high (greater than 5 micrograms/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 micrograms/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.

Adult↗
PubMed1988

Improvement of in vitro fertilisation after treatment with buserelin, an agonist of luteinising hormone releasing hormone.

Treatment with buserelin, an agonist of luteinising hormone releasing hormone, and human menopausal gonadotrophin was compared with the conventional treatment of clomiphene citrate and human menopausal gonadotrophin in the outcome of in vitro fertilisation. Seventy seven infertile women had 83 cycles of treatment with buserelin and human menopausal gonadotrophin, and concurrently another 328 infertile women were treated with clomiphene citrate and human menopausal gonadotrophin. Seven (8%) cycles were cancelled owing to inadequate super-ovulation or ovarian hyperstimulation in the women receiving buserelin and 103 (31%) were cancelled because of poor follicular development in those receiving clomiphene citrate. The mean number of oocytes recovered was significantly higher with buserelin (9.5 (SD 4.5) v 5.5 (2.2)) as was the mean number of embryos obtained (4.3 (2.4) v 2.9 (1.7)). Significantly more women who had an embryo transfer became clinically pregnant after treatment with buserelin (53% (30/57) v 30% (48/159), or 36% v 14% of treatment cycles). Altogether 33% (10) of pregnancies in women treated with buserelin were multiple compared with 23% (11) in those treated conventionally. Of the 17 completed pregnancies in women treated with buserelin, 11 resulted in the birth of live babies (eight singletons, two sets of twins, and one set of triplets) and six failed, five before 12 weeks' gestation and one at 22 weeks. The 13 continuing pregnancies (32 weeks) were eight singletons, two sets of twins, and three sets of triplets. Of the 48 completed pregnancies in women treated with clomiphene citrate, 35 resulted in the birth of live babies (26 singletons, five sets of twins and four sets of triplets) and 13 failed, eleven before 12 weeks' gestation and two by 27 weeks. Buserelin increased the chance of pregnancy after in vitro fertilisation compared with conventional treatment, but the risk of multiple pregnancy may be increased.

Buserelin↗