About 15% of all couples experience infertility at some time during
their reproductive lives. Increasingly, infertility can be treated by the use
of assisted reproductive technologies, such as in vitro fertilization (IVF),
gamete intra-fallopian transfer, and intracytoplasmic sperm injection.
Gonadotropin treatment to increase the number of oocytes is a common element of
these programs. A major cause for female infertility is chronic anovulation.
Patients suffering from this condition are also treated with gonadotropins with
the aim to achieve monofollicular development.
Gonadotropin preparations for infertility treat-ment are traditionally
derived from postmenopausal urine. The urinary preparations contain
follicle-sti-mulating hormone (FSH), but are typically less than 5% pure. The
preparations also contain luteinizing hormone (LH) as a contaminant.
Recombinant DNA technology allows the reproducible manufacturing of FSH
preparations of high purity and specific activity, devoid of urinary
contaminants. Recombinant FSH is produced using a Chinese hamster ovary (CHO)
cell line, transfected with the genes encoding for the two human FSH subunits
(van Wezenbeek, 1990; Howles, 1996). The isolation procedures render a product
high purity (at least 97%), devoid of LH activity and very similar to
Currently, there are two clinically approved recombinant FSH-containing
drug products on the market. These are Gonal-F , manufactured by Merck Serono
S.A., and Puregon , with the brand name of Follistim in the United States,
manufactured by NV Organon. Regulatory authorities have issued two distinct
International Non-proprietary Names for the two corresponding recombinant FSH
drug substances, i.e. follitropina (Gonal-F
) and follitropinb (Puregon /Follistim ). Thus, the two products should be considered
similar, but not identical preparations containing distinct active ingredients.