Follicle Stimulating Hormone

INTRODUCTION

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 of

high purity (at least 97%), devoid of LH activity and very similar to natural FSH.

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.