What are injectable gonadotropins?
Injectable gonadotropins are medical preparations of naturally occurring hormones that the brain produces to stimulate the ovaries to produce hormones and to prepare eggs for release. The two hormones are follicle stimulating hormone, or FSH, and lutenizing hormone, or LH.
What do these two hormones do?
Human eggs wait in the ovary in a partially mature state. Early in each menstrual cycle, the brain sends FSH to the ovary, which in turn selects a group of eggs to begin the maturation process. The FSH stimulates the maturation of the eggs, and stimulates the release of increasing amounts of estrogen. LH is released along with the FSH, and stimualtesthe ovary to release additional hormones that also play a role in egg development. Typically, only one of the recruited eggs becomes fully mature. When this single, dominant egg is ready for release, a great, one-time release of LH, known as the LH surge, tells the overy to release the mature egg.
When we use HMG (Human Menopausal Gonadotropin) or FSH as a medication, we bypass the body's normal process of egg development and release. In this way, we can induce ovulation in women who do not ovulate on their own, produce more than one mature egg each cycle and fix faulty egg developing systems. These medications are either used by themselves, in conjuction with intrauterine insemination procedures, or for in vitro fertilization.
What are Pergonal, Humegon, Fertinex and Repronex?
Pergonal, Repronex, Humegon, Fertinex are commercial names for the naturally derived HMG and FSH preparations available in the United States. They are all manufactured by purifying the secreted hormones from human urine. Pergonal is 50% LH and 50% FSH. It is given by injection only, using a 1½ inch needle injected deep into the muscle, usually in the backside. Humergon is virtually identical to Pergonal, but is manufactured by a different company. Repronex can be injected subcutaneously with a smaller needle (approximately ¼"). Fertinex is newer form of FSH. Its advantage is a better purification process, making it also injectable using a smaller needle.
What are Gonal-F and Follistim?
These are recombinant forms of purified FSH, manufactured by a biosynthetic method. Due to increased purity, both products can be given subutaneously with a small needle similar to Fertinex and Repronex.
Is one preparation superior to another?
In theory, FSH is more important than LH in the development of mature eggs. However, purified FSH and HMG seem to work equally well in terms of pregnancy rates. Some centers use a combination of the two preparations in patients' cycles. The E2 may rise more slowly or to a lower peak level in the very beginning of the cycle with the recombinants. This does not appear to affect the outcome.
How is HMG given?
HMG is given by intramuscular (IM) injection either once or twice daily. Repronex, Fertinex and the recombinants require a smaller needle injected just below the skin surface.
How is the cycle monitored?
Cycles typically start on the third day of the menstrual cycle, although day four or five starts are not uncommon. The development of the eggs is monitored by blood test for estradiol and transvaginal ultrasound examinations for follicle size and endometrial thickness.