Dose-finding study for the use of long-acting gonadotrophin-releasing hormone analogues prior to ovarian stimulation for IVF

S.F. Yim,1, I.H. Lok, L.P. Cheung, C.M. Briton-Jones, T.T.Y. Chiu and C.J. Haines

Department of Obstetrics and Gynaecology, Prince of Wales Hospital, The Chinese University of Hong Kong, New Territories, Hong Kong, SAR, China


    Abstract
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 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
Gonadotrophin-releasing hormone (GnRH) analogues improve the outcome of treatment with IVF by increasing the number and quality of oocytes retrieved and by reducing cycle cancellation rates. Whilst short-acting GnRH analogues are most commonly used, depot preparations are now available that are more convenient for patient use. Some studies have reported that pregnancy rates with depot GnRH analogues are similar to those of short-acting preparations, but others have suggested that the more profound down-regulation seen with depot GnRH analogues results in inferior embryo quality. The purpose of this study was to determine whether a lower than conventional dose of a depot GnRH analogue may be more appropriate for use in ovarian stimulation prior to IVF. Sixty patients were randomized to receive either 3.75 mg (conventional dose) or 1.87 mg (low dose) triptorelin prior to ovarian stimulation for IVF. Suppression was measured using serum concentrations of LH measured 2 and 3 weeks after the administration of the GnRH analogues, the dose of gonadotrophin used and the time to resumption of menses. Mean concentrations of LH were 2.2 ± 1.0 and 1.1 ± 0.6 IU/l in the conventional dose group and 3.5 ± 5.5 and 2.7 ± 1.9 IU/l in the low dose group (P < 0.05 at 2 and 3 weeks). There were no significant differences between the doses of gonadotrophins used, the number of oocytes and embryos available and the time to resumption of menses, nor in the pregnancy rates. Although the degree of suppression as measured biochemically was more profound with the conventional dose, this did not affect the IVF outcome. The use of a lower dose therefore appears to be equally effective and could contribute to a reduction in the cost of treatment.

Key words: gonadotrophin-releasing hormone analogue/IVF/pituitary-ovarian axis


    Introduction
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
Gonadotrophin releasing hormone (GnRH) analogues are commonly used in conjunction with gonadotrophins to achieve ovarian stimulation for IVF. Their use improves oocyte yield and quality and reduces cycle cancellation rates caused by premature luteinization (Ron-El et al., 1991Go; Hughes et al., 1992Go). On a long down-regulation protocol, a GnRH analogue is administered to place the ovaries in a quiescent state prior to stimulation with exogenous gonadotrophins. Short-acting analogues are most commonly used, which are administered either s.c. or intranasally on at least a daily basis until satisfactory down-regulation is achieved. Long-acting analogues are now also available, and these are given as a single s.c. or i.m. injection. The long-acting preparations are convenient for patient use, but they have potential disadvantages arising from the fact that they produce more profound down-regulation than do the short-acting preparations. Greater down-regulation results in the need for higher doses of gonadotrophins. Also, when LH concentrations are suppressed below 0.5 IU/l, stimulation using gonadotrophins containing a low LH content results in a lower yield of oocytes (Fleming et al., 1998Go). Finally, the ovarian suppression resulting from depot GnRH analogue use may inhibit ovulation for some months after treatment, so despite the failure to achieve a pregnancy, the patient may remain amenorrhoeic for some months after the IVF treatment cycle. However, in those patients without extreme LH suppression, pregnancy rates have been encouraging (Dada et al., 1999Go).

A previous observational study of full or half dose long-acting GnRH analogue treatment in women with normal ovarian function found that pituitary suppression was similar with each dose (Balasch et al., 1992Go). Both doses resulted in satisfactory suppression within 14 days of injection. However, different doses have not been tested in the IVF setting in a randomized controlled manner.

The aim of this study was to determine whether low dose long-acting GnRH analogue administration was effective in achieving pituitary suppression prior to IVF without causing the adverse effects of severe suppression associated with standard dose treatment.


    Materials and methods
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 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
Sixty patients undergoing IVF in the Assisted Reproductive Technology Unit of the Prince of Wales Hospital, the Chinese University of Hong Kong, were recruited. A detailed explanation concerning the reason for the study and the treatment involved was given and written consent was obtained. The study was approved by the Clinical Ethics Committee of the Chinese University of Hong Kong.

Exclusion criteria included patients with baseline LH concentrations >12 IU/l, oestradiol >300 pmol/l and couples in which there was male factor infertility (count <20x106/ml, motility <40%, morphology >50% abnormal forms).

Patients were allocated randomly by the use of block randomization into two groups. Group 1 received triptorelin 3.75 mg i.m. while group 2 subjects received triptorelin 1.87 mg i.m., each on day 2 of menses. LH and oestradiol concentrations were performed on the day of triptorelin injection and again 14 and 21 days after injection. All subjects had achieved satisfactory suppression (LH <5 IU/l, oestradiol <200 pmol/l, no cystic structures >10 mm diameter on ovarian ultrasound) by this time. Ovarian stimulation began in the usual manner 2 or 3 weeks after GnRH analogue administration. Human menopausal gonadotrophin (HMG) 225 IU daily was then given daily for women aged >=33 years and HMG 300 IU daily for those aged >=36 years or with a previous poor ovarian response. The monitoring of the response to ovarian stimulation during the IVF cycles was the same as in standard IVF treatment cycles. A dose of 10 000 IU of human chorionic gonadotrophin (HCG) was given when there were at least three follicles >=15 mm in diameter. Oocyte retrieval was performed 34–38 h after HCG administration. Embryo transfer was performed 48 h later. Luteal phase support was given in the form of HCG 2000 IU every third day for four doses.

After oocyte retrieval, the number of oocytes obtained, the quality of the oocytes, the number of fertilized oocytes and the number of embryos available for transfer were recorded. The `after-effects' of the drug were assessed by recording the date of return of the menstrual period following the withdrawal bleed after embryo transfer in cases where no pregnancy resulted. The concentration of LH 4 weeks after withdrawal bleeding was measured.

Statistical analysis was performed using Statistics Package for Social Sciences (SPSS) version 8.0 for Windows. The independent samples t-test was used to examine the difference in the measurements of oestradiol/LH concentrations, the doses of gonadotrophins used, the number of oocytes retrieved and fertilized, the number of embryos transferred and the number of days required to return to normal pituitary–ovarian function.

The calculation of the sample size was based on a previous study (Fleming et al., 1998Go) on the effects of suppression of LH using a conventional dose of a GnRH analogue before the start of IVF cycles. They found a mean difference in LH concentration of 1.4 IU/l and a SD of 0.9 IU/l in their patients after 2 weeks of treatment.

Therefore eight patients in each arm would be the least number necessary to obtain 80% power with a type I error {alpha} = 0.05. To increase the power and reduce the error, 30 cases were recruited in each arm.


    Results
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 Abstract
 Introduction
 Materials and methods
 Results
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One case from each of the study groups was excluded. One subject from group 1 withdrew from the study for personal reasons. One subject from group 2 was excluded because of a high LH concentration before starting the GnRH analogue dose.

The mean age of the patients of group 1 was 33.1 ± 2.9 years and in group 2 was 33.8 ± 3.2 years. The mean number of years of infertility in group 1 was 4.2 ± 2.6 years and in group 2 was 5.2 ± 2.7 years. The mean baseline LH in group 1 was 4.4 ± 2.5 IU/l and in group 2 was 4.2 ± 1.8 IU/l. Mean concentrations of LH 2 and 3 weeks after GnRH analogue administration were 2.2 ± 1.0 and 1.1 ± 0.6 IU/l in the conventional dose group and 3.5 ± 5.5 and 2.7 ± 1.9 IU/l in the low dose group (P < 0.05 for each comparison). Five in the standard dose group and four in the low dose group required 3 weeks for adequate suppression. However, the mean number of ampoules of gonadotrophins required for ovarian stimulation was similar (42.7 ± 9.7 in group 1 and 42.1 ± 8.5 in group 2). There were also no significant differences in the number of oocytes retrieved (9.3 ± 5.2 in group 1 versus 9.5 ± 8.5 in group 2, P = 0.05) nor in the number of embryos available for transfer (3.9 ± 2.9 in group 1 versus 3.9 ± 4.1 in group 2).

There was no difference between pregnancy rates (31.0% in group 1 versus 21.7% in group 2). For those patients who failed to conceive, LH was measured 4 weeks after withdrawal bleeding. The concentration of LH was not significantly different between groups (1.6 ± 1.5 IU/l in group 1 versus 2.3 ± 2.7 IU/l in group 2). For those patients who were not pregnant, the mean time to resumption of menses after withdrawal bleeding was 46.9 ± 15.0 days in group 1 and 44.2 ± 13.2 days in group 2; however, only 15 in each group could be contacted afterwards (Table IGo).


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Table I. Outcomes
 

    Discussion
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 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
Long-acting GnRH analogues were primarily designed to improve compliance and acceptability in women with endometriosis or uterine fibroids who needed to use this treatment for a prolonged period of time. However, the single dosing made this form of administration attractive for use in long down-regulation protocols in IVF treatment cycles. As these long acting preparations were designed to produce profound, sustained down-regulation, there were some untoward effects that made them less attractive for use in the IVF situation. Devreker et al. (1996) reported lower implantation rates in IVF cases where long-acting GnRH analogues were used, and it was suggested that the long-acting GnRH analogue might interfere with the embryo quality or the endometrial receptivity in IVF cycles. Previously, GnRH analogues had been found in small quantities in follicular fluid in IVF cycles in which a short-acting GnRH analogue had been used. Devreker et al. (1996) suggested that follicular fluid concentrations of the analogues may be higher when depot preparations are used, and that this may be the reason for the poor embryo quality. Neuspiller et al. (1998), on the other hand, found comparable fertilization and implantation rates with short- and long-acting analogues. Hsieh et al. (2000) recently examined the effect of a lower dose depot GnRH analogue and a short-acting GnRH analogue in IVF cycles. They found a comparable result in the pregnancy rates of the IVF cycles in their non-randomized study. However, the degree of pituitary suppression and the after-effects were not studied.

The effect of a lower dose of a depot GnRH analogue was studied as it was suspected that this would provide adequate suppression without causing the problems of oversuppression associated with the standard dose. Significantly more pronounced suppression was found, as measured by LH concentrations on days 14 and days 21 after injection of a standard dose of the long-acting GnRH analogue than with the low dose (P < 0.05). Adequate suppression was identified when the LH concentration was less than 5 IU/l. Balasch et al. (1992), showed comparable pituitary–ovarian suppression with standard and a half dose of a long-acting GnRH analogue in women with normal ovarian function. In the current study, the mean LH on day 14 of the standard and low dose cycles were 3.5 and 2.2 IU/l respectively. Adequate suppression was achieved in each group although the difference was statistically significant. The number of cases requiring 21 days to achieve an adequate LH concentration was similar. There were four cases in the group receiving low dose and five in the group receiving standard dose. Therefore, both dosages are adequate for pituitary–ovarian suppression.

There were two cases in each group in which over-suppression (defined as LH concentration <1 IU/l) was present. When this occurred, the total dose of gonadotrophin used was significantly higher (a mean of 52 versus 42 ampoules of HMG used). Of the cases with over-suppression, one from each group developed ovarian stimulation syndrome and one from the low dose group had a poor response to gonadotrophin stimulation.

Interestingly, it had previously been observed that patients who had used the long-acting preparation and had not then become pregnant often complained about the delay in resumption of their normal menstrual cycle. Oestradiol and LH concentrations were measured 4 weeks after bleeding resulting from failed IVF treatment and no statistically significant difference between groups was found. It was also observed that the time taken for spontaneous resumption of menstrual bleeding (not the withdrawal bleeding after the failed IVF treatment) was around 6 weeks in each group. The difference between the two groups was not statistically significant.

Concerning the outcome measures for IVF, the number of oocytes retrieved and fertilized and the number of embryos that were suitable for transfer was similar. The pregnancy rates and also the abortion rates were similar. There was no apparent adverse effect on implantation from this study.

It is therefore concluded that both doses of the long-acting GnRH analogue were adequate for IVF purposes, and that the degree of over-suppression was acceptable. The use of a lower dose may be just as effective and may contribute to a reduction in the cost of treatment.


    Acknowledgments
 
We would like to thank the staff working in the Assisted Human Reproductive Unit of the Prince of Wales Hospital including Ms Sing, Ms Chan, Ms Cheung, Ms Tang, Ms Tjer and Ms Yeung for their kind assistance in collecting the data. We would also like to thank Ferring, Sweden, for their help in performing the study.


    Notes
 
1 To whom correspondence should be addressed. E-mail: sfyim{at}cuhk.edu.hk Back


    References
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
Balasch, J., Gomez, F., Casamitjana, R. et al. (1992) Pituitary–ovarian suppression by the standard and half-doses of D-Trp-6-luteinizing hormone-releasing hormone depot. Hum. Reprod., 7, 1230–1234.[Abstract]

Dada, T., Salha, O., Baillie, H.S. and Sharma, V. (1999) A comparison of three gonadotrophin-releasing hormone analogues in an in-vitro fertilization programme: a prospective randomized study. Hum. Reprod., 14, 288–293.[Abstract/Free Full Text]

Devreker, F., Van den Bergh, M., Govaerts, I. et al. (1996) The long-acting gonadotrophin-releasing hormone analogues impaired the implantation rate. Fertil. Steril., 65, 122–126.[ISI][Medline]

Fleming, R., Lloyd, F., Herbert, M. et al. (1998) Effects of profound suppression of luteinizing hormone during ovarian stimulation on follicular activity, oocyte and embryo function in cycles stimulated with purified follicle stimulating hormone. Hum. Reprod., 13, 1788–1792.[Abstract]

Hsieh, Y.Y., Tsai, H.E., Chang, C.C. et al. (2000) Comparison of a single half-dose, long-acting form of gonadotrophin-releasing hormone analog (GnRH-a) and a short acting form of GnRH-a for pituitary suppression in a controlled ovarian stimulation program. Fertil. Steril., 73, 917–820.

Hughes, E.G., Sagle, M.A., Fedorkow, D.M. et al. (1992) The routine use of gonadotrophin-releasing hormone agonists prior to in vitro fertilization and gamete intraFallopian transfer: a meta-analysis of randomized controlled trials. Fertil. Steril., 58, 888–896.[ISI][Medline]

Neuspiller, F., Levy, M., Remohí, J. et al. (1998) The use of long- and short-acting forms of gonadotrophin-releasing hormone analogues in women undergoing oocyte donation. Hum. Reprod., 13, 1148–1151.[Abstract]

Ron-El, R., Herman, A., Golan, A. et al. (1991) Gonadotrophins and combined gonadotrophin-releasing hormone agonist–gonadotrophins protocols in a randomized prospective study. Fertil. Steril., 55, 574–578.[ISI][Medline]

Submitted on July 28, 2000; accepted on November 30, 2000.