Follitropin alpha in infertility: a review.
Follitropin alpha (recombinant human follicle-stimulating hormone; follitropin alfa) is a recombinant form of follicle-stimulating hormone (FSH), an endogenous gonadotrophin. Unlike FSH products derived from urine [menotropins (human menopausal gonadotrophins), urofollitropin and highly purified urofollitropin], follitropin alpha is readily available and shows batch-to-batch consistency. As well, it is free of luteinising hormone (LH) activity and contaminant urinary proteins and can be self-administered subcutaneously. In women undergoing in vitro fertilisation-embryo transfer (IVF-ET), follitropin alpha appears to have a greater stimulatory effect on follicular development than urine-derived FSH products as a group. In direct comparisons it had similar effects to urofollitropin but produced more oocytes per stimulated cycle than highly purified urofollitropin and menotropins. Preliminary results of 1 small trial indicate similar efficacy for follitropin alpha and follitropin beta. Rates of pregnancy, live births and multiple births have been similar among all treatment groups. As ovulation induction in women with clomifene-resistant WHO group II anovulation, follitropin alpha produces rates of ovulation, follicular development and pregnancy resembling those seen with urofollitropin or highly purified urofollitropin. A long term low-dose regimen of follitropin alpha is associated with a lower number of follicles and a trend toward fewer multiple births compared with conventional follitropin alpha or urofollitropin regimens. Data from women with WHO group I anovulation and from infertile men are scant. Tolerability has not differed between follitropin alpha and other FSH products. The incidence of general events (e.g. headache, nausea, ovarian cyst), local irritations at injection site and ovarian hyperstimulation syndrome resembled those for comparator FSH products. However, it appears that follitropin alpha can be tolerated in instances of severe allergic reaction to urine-derived products.


CONCLUSIONS
In women undergoing IVF-ET, follitropin alpha appears to have a greater stimulatory effect on follicle development than urine-derived FSH products as a group and is at least as well tolerated as these preparations; preliminary data indicate similar efficacy to follitropin beta. At present, its efficacy in women with WHO group II anovulation disorder has been shown to be similar to that of the older products. Compared with urinary FSH products, the benefits of follitropin alpha lie in its reliable supply, consistency of production, lack of contaminant urinary proteins and ease of self-administration. Given these practical advantages, and the apparently greater effect on follicular development overall in women undergoing IVF-ET, recombinant products such as follitropin alpha are expected to eventually replace older urine-derived FSH preparations and claim a prominent position in the treatment of infertility.
Goa
K L
KL
Adis International Limited, Auckland, New Zealand. demail@adis.co.nz
Wagstaff
A J
AJ