Gonadotropin preparations

All three hormones—FSH, LH, and hCG—are heterodimers that share an identical a chain in addition to a distinct chain that confers receptor specificity. The 13 chains of hCG and LH are nearly identical, and these two hormones are used interchangeably. All the gonadotropin preparations are administered by subcutaneous or intramuscular injection, usually on a daily basis. Half-lives vary by preparation and route of injection from 10 to 40 hours. 

Bioassays Used to Compare the Potency of Different Gonadotropin Preparations... 

Potencies op Gonadotropin Preparations Purified by Methods Discussed in Sections 3 and 4... 

The menotropins, human menopausal gonadotropin (HMG) and urofollitropin are prepared from the urine of postmenopausal women. HMG has approximately equal amounts of FSH an LH. Urofollitropin has only FSH activity. Follitropin alpha and follitropin beta are two FSH products which are made with recombinant DNA technology. Lutropin alpha is recombinant human LH. Human chorionic gonadotropin (HCG) is produced in the placenta and excreted in the urine. It has mainly LH activity. Choriogonadotropin alpha is the world s first recombinant chorionic gonadotropin (r-hCG) for the treatment of anovulation, the most common cause of infertility in women. 

FSH has been commercially available since the 1960s. It was first extracted from the urine of postmenopausal women, which contains a substance with FSH-like properties (but with 4% of the potency) and an LH-like substance. This purified extract of FSH and LH, derived from the urine of postmenopausal women, remains available and is known as menotropins, or human menopausal gonadotropins (hMG). A purified preparation of human FSH, also extracted from the urine of postmenopausal women, contains virtually no LH and is know as urofollitropin, or urinary FSH (uFSH). In 1996, a synthetic modified form of FSH became available, known as follitropin alpha, or recombinant FSH (rFSH). Preparations of rFSH have batch-to-batch consistency and are free from possible urinary contaminants. The cost of rFSH is about three times that of hMG. It is controversial whether in vitro fertilization protocols using rFSH are significantly more successful than protocols using uFSH or hMG. 

These preparations are used in states of infertility to stimulate ovarian follicle development in women and spermatogenesis in men. In both sexes, they must be used in conjunction with a luteinizing hormone, ie, human chorionic gonadotropin (hCG), to permit ovulation and implantation in women and testosterone production and full masculinization in men. 

There is no LH preparation presently available for clinical use. Human chorionic gonadotropin— with an almost identical structure—is available and can be used as a luteinizing hormone substitute. 

Lee CY, Ryan RJ (1973) Interaction of ovarian receptors with human luteinizing hormone and human chorionic gonadotropin. Biochemistry 12 4609 1619 Marana R, Robertson DM, Suginami H, Diczfalusy E (1979) The assay of human follicle-stimulating hormone preparations the choice of a suitable standard. Acta Endocrin 92 599-614... 

The ovaries perform two major functions (i) the storage, maturation, and expulsion of healthy haploid germ cells (i.e., oocytes) for fertilization, and (ii) the synthesis and secretion of hormones to prepare the reproductive tissues for the establishment and maintenance of pregnancy, to properly regulate gonadotropin secretion from the hypothalamic-pituitary axis, to induce appropriate sexual behaviors, and to provide lactation. The two primary functional units in the ovaries are the maturing follicles and the corpora lutea. 

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