Tamoxifen and Ovulation Induction
Tamoxifen is an anti-oestrogen and it is generally considered to increase fertility rates in a similar way to clomiphene.
In contrast to clomiphene, however, tamoxifen does not increase follicular phase FSH and LH levels, although there is an increase in oestradiol levels and luteal phase progesterone. It has, therefore, been postulated that tamoxifen improves follicular development by direct action on the ovary rather than through the hypothalamic-pituitary axis (menstrual cycles).
We usually start with 20mg daily from the second to the sixth day and build up to a maximum of 80mg.
When used for short periods, tamoxifen does not appear to be associated with any increased risk of either ovarian or endometrial malignancy.
Early studies indicated similar success rates between tamoxifen and clomiphene. In one series of 66 anovulatory patients, both drugs achieved pregnancy rates of 80% within nine months.
When clomiphene fails to achieve ovulation or pregnancy, tamoxifen may prove to be effective and vice versa.
Some authorities have recommended tamoxifen as their first choice for women with polycystic ovary syndrome (PCOS). The argument has been that PCOS is associated with relatively high levels of LH and this seems to reduce the chance of conception and increase the chance of miscarriage. Unlike clomiphene , tamoxifen does not further increase LH levels. Metformin may supersede tamoxifen and clomiphene as the first choice agent in PCOS (12).
Related Medical Abstracts - Click on the paper title:-
- Comparison of tamoxifen and clomiphene citrate for ovulation induction: a meta-analysis. (2005-01)
- Management of anovulatory infertility associated with polycystic ovary syndrome: tamoxifen citrate an effective alternative compound to clomiphene citrate. (2004-01)
- A prospective randomized trial comparing clomiphene citrate with tamoxifen citrate for ovulation induction. (2001-01)
- Tamoxifen: an alternative approach in clomiphene resistant polycystic ovarian syndrome patients (1993)Effects of the anti-oestrogens, clomiphene and tamoxifen, on the cervical factor in female infertility (1984)
- Treatment of infertile women with a deficient postcoital test with two antiestrogens: clomipheneand tamoxifen (1984) Tamoxifen treatment in women with failure of clomiphene citrate therapy (1989)
- Antiestrogens as treatment of female and male infertilities (1987)
- Endocrine profiles in tamoxifen-induced conception cycles (1984)
- Luteotropic effects of tamoxifen in infertile women (1984)
- Action of tamoxifen on folliculogenesis in the menstrual cycle of infertile patients (1983)
- Comparison between tamoxifen and clomiphene for induction of ovulation (1982)
Ovulation Induction - Summary
With the exception of primary ovarian failure (the menopause), ovulatory disorders can usually be successfully treated. Ovulation induction regimens depend on the underlying cause (infertility cause).
Sometimes appropriate advice may be all that is required. When weight loss is responsible for secondary amenorrhoea (amenorrhoea causes), improved diet leading to correction of your weight may prove to be successful.
The main drugs used to overcome anovulation are clomiphene (clomiphene)(clomiphene citrate), tamoxifen (tamoxifen infertility), bromocriptine (bromocriptene), metformin (12), and gonadotrophins (gonadotrophins).
risks of ovulation induction
There are three concerns associated with drugs used to induce ovulation:
- They are associated with a greater chance of multiple pregnancy. The general rate of twins in the population is one in every eighty deliveries but with clomiphene, it is one in twenty or a four-fold increase. Higher order multiple pregnancies (e.g. triplets and quads) can occur with clomiphene but this is rare. Injections of gonadotrophins are more likely than clomiphene to result in multiple pregnancy.
- Occasionally ovulation induction can lead to ovarian hypersensitivity syndrome (OHSS).
- Finally, there has been concern that ovulation induction treatments may increase the chance of ovarian cancer. A comparison was made of the risk of cancer among women who received clomiphene with the risk among infertile women who did not receive it. There were 11 invasive or borderline malignant ovarian tumors, as compared with an expected number of 4.41994-01. A confounding factor is that infertility is itself associated with an increased risk. Furthermore, the risk is reduced with secondary infertility and is dependent on the causation of the infertility.2004-01Several infertility units have reported their data. Some seemed to confirm the link between clomiphene and ovarian cancer but the majority have produced reassuring results.1999-02,2004-02 2006-01
Related Medical Abstracts - Click on the paper title:-
- Induction of ovulation and ovarian cancer: a critical review of the literature. (2006-01)
- Ovarian cancer risk associated with varying causes of infertility.(2004-01)
- Ovarian cancer risk after the use of ovulation-stimulating drugs.(2004-02)
- Fertility drugs and the risk of breast and ovarian cancers: Results of a long-term follow-up study. (1999)
- Ovulation induction and ovarian tumours: the debate continues.(1999-02)
- Ovulation induction, infertility, and ovarian cancer risk (1996)
- The risk of ovarian cancer after treatment for infertility (1995)
- Ovarian stimulation and ovarian tumours: a critical reappraisal (1995)
- Ovarian tumors in a cohort of infertile women (1994)
- Characteristics relating to ovarian cancer risk: Collaborative analysis of 12 US case-control studies. II. Invasive epithelial ovarian cancers in white women (1992)
Related Medical Abstracts - Click on the paper title:-
- Ovulation induction using s.c. pulsatile gonadotrophin-releasing hormone: Effectiveness of different pulse fre quencies (1996)
- Investigation and treatment of amenorrhoea resulting in normal fertility (1979)
Ovulation Induction Monitoring
Monitoring may be required to confirm that ovulation is occurring and to ensure that too many follicles are not developing. Blood tests for progesterone levels around the twenty-first day of the cycle provide an indication of ovulation (Q9.17). Ultrasound monitoring of follicular development is helpful with tablet treatment (clomiphene and tamoxifen) and is really essential with gonadotrophins. When controlled ovarian hyperstimulation is undertaken in IVF protocols, oestradiol levels are used. The need for monitoring hormone levels in IVF protocols has been questioned.1998-01, 2006-01
Related Medical Abstracts - Click on the paper title:-
- Monitoring ovarian stimulation: are hormonal assessments necessary? (2006-01)
- Follicle tracking of women receiving clomiphene citrate for ovulation induction. (2005-01)
- The role of infertility nurses in ovulation induction programmes (2001)
- Comparison of several one-step home urinary luteinizing hormone detection test kits to OvuQuick. (2001-02)
- The usefulness of a urinary LH kit for ovulation prediction during menstrual cycles of normal women. (1996-01)
- Is it possible to run a successful ovulation induction program based solely on ultrasound monitoring? The importance of endometrial measurements (1991-01)
- The clinical value of Clearplan home ovulation detection kits in infertility practice. (1991-02)
- Single serum progesterone measurement in the mid-luteal phase as an index of ovulation.(1987-01)
- Plasma progesterone levels as an index of ovulation. (1983-01)
- The value of a single serum progesterone measurement in the midluteal phase as a criterion of a potentially fertile cycle ("ovulation") derived form treated and untreated conception cycles. (1982-01)
- Plasma oestradiol and progesterone estimation for the monitoring of induction of ovulation with clomiphene and chorionic gonadotrophin. (1975-01)
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This is the personal website of David A Viniker MD FRCOG, Consultant Obstetrician and Gynaecologist at Whipps Cross University Hospital, London - Specialist Interests - Reproductive Medicine including Infertility, PCOS, PMS, Menopause and HRT.
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