Follicle-stimulating hormone (FSH), the active component in Follistim® AQ (follitropin beta injection), is required for normal follicular growth, maturation, and gonadal steroid production. In women, the level of FSH is critical for the onset and duration of follic-ular development, and consequently for the timing and number of follicles reaching maturity. Follistim® AQ (follitropin beta) stimulates ovarian follicular growth in women who do not have primary ovarian failure. In order to effect the final phase of follicle maturation, resumption of meiosis and rupture of the follicle in the absence of an endogenous LH surge, human chorionic gonadotropin (hCG) must be given following treatment with Follistim® AQ (follitropin beta) when patient monitoring indicates appropriate follicular development parameters have been reached.

Pharmacokinetics

Exposures of follitropin beta from Follistim® AQ (follitropin beta) and Follistim®are expected to be equivalent.

Absorption

The bioavailability of Follistim®following subcutaneous and intramuscular administration was investigated in healthy, pituitary-suppressed, female subjects given a single 300 IU dose. After subcutaneous or intramuscular injection the apparent dose absorbed was 77.8% and 76.4%, respectively.

The subcutaneous (455.6 ± 141.4 IU*h/L) and intramuscular (445.7 ± 135.7 IU*h/L) routes of administration were equivalent with respect to area under the curve (AUC) in healthy, pituitary-suppressed, female subjects given a single 300 IU dose. However, equivalence could not be established for peak serum FSH levels (Cmax) between the subcutaneous (5.41 ± 0.72 IU/L) and intramuscular (6.86 ± 2.90 IU/L) routes of administration.

The pharmacokinetics and pharmacodynamics of a single, intramuscular dose (300 IU) of Follistim®were also investigated in a group (n=8) of gonadotropin-deficient, butotherwise healthy women. In these women, FSH (mean ±SD) AUC was 339 ± 105 IU*h/L, Cmax was 4.3 ± 1.7 IU/L. Cmax occurred at approximately 27 ± 5.4hours after intramuscular administration.

A multiple, dose proportionality, pharmacokinetic study of Follistim®was completed in healthy, pituitary-suppressed, female subjects given intramuscular doses of 75, 150, or 225 IU for 7 days. Steady-state blood concentrations of FSH were reached with all doses after 4 days of treatment based on the minimum concentrations of FSH just prior to dosing (Cmin). Peak blood concentrations with the 75, 150, and 225 IU dose were 4.65 ±1.49 IU/L, 9.46±2.57 IU/L and 11.30 ±1.77 IU/L, respectively.

A multiple, dose proportionality, pharmacokinetic study of Follistim®was completed in healthy, pituitary-suppressed, female subjects given subcutaneous doses of 75, 150, or 225 IU for 7 days. Steady-state blood concentrations of FSH were reached with all doses after 5 days of treatment based on the minimum concentrations of FSH just prior to dosing (Cmin). Peak blood concentrations with the 75, 150, and 225 IU dose were 4.30 ±0.60 IU/L, 8.51±1.16 IU/L and 13.92 ±1.81 IU/L, respectively.

Distribution

The volume of distribution of Follistim®in healthy, pituitary-suppressed, female subjects following intravenous administration of a 300 IU dose was approximately8 L.

Metabolism

The recombinant FSH in Follistim® AQ (follitropin beta) is biochemically very similar to urinary FSH and it is therefore anticipated that it is metabolized in the same manner.

Elimination

The elimination half-life (t½) following a single intramuscular dose (300 IU) of Follistim®in female subjects was 43.9 ± 14.1 hours (mean ± SD). The elimination half-life following a 7-day intramuscular treatment with 75, 150, or 225 IU was 26.9 ± 7.8 hours (mean ±SD), 30.1 ±6.2 and 28.9 ±6.5, respectively.

Special Populations

The effect of body weight on the pharmacokinetics of Follistim®was evaluated in a group of European and Japanese women who were significantly different in terms of body weight. The European subjects had a body weight of (mean ± SD) 67.4 ± 13.5 kg and the Japanese subjects were 46.8 ±11.6kg. Following a single intramuscular dose of 300 IU of Follistim®, the AUC (IU*h/L) was significantly smaller in European subjects (339 ±105) than in Japanese subjects (544 ±201). However, clearance per kg of bodyweight was essentially the same for the respective groups (0.014 and 0.013 1*h^-1kg^-1).

The pharmacokinetics of Follistim®have not been determined in special populations such as geriatric, pediatric, renally impaired, and hepatically impaired patients.

Clinical Studies

The efficacy of Follistim®was established in four controlled, clinical studies [three studies for Assisted Reproductive Technologies (ART) and one study for Ovulation Induction], three of which are described below. In these comparative studies, there were no clinically significant differences between treatment groups in study outcomes.

Assisted Reproductive Technologies (ART)

Follistim®was studied in a randomized, assessor-blind, group comparative, multi-center safety and efficacy study of 981 infertile women treated for one cycle with in vitro fertilization with Follistim®or urofollitropin after pituitary suppression with a GnRH agonist. The results with Follistim®are summarized in Table 1.

Table 1. Results From a Randomized, Assessor-blind, Group Comparative, Multicenter Safety and Efficacy Study of Follistim® in Infertile Women Treated With In Vitro Fertilization After Pituitary Suppression With a GnRH Agonist¹

Follistim®was also evaluated in a randomized, assessor-blind, group comparative, single center safety and efficacy study in 89 infertile women treated with in vitro fertilization with Follistim®or menotropins without pituitary suppression with a GnRH agonist. The results with Follistim®are summarized in Table 2.

Table 2. Results From a Randomized, Assessor-blind, Group Comparative, Single Center Safety and Efficacy Study of Follistim® in Infertile Women Treated With In Vitro Fertilization Without Pituitary Suppression¹

Ovulation Induction

Results from a randomized, assessor-blind, group comparative, multicenter safety and efficacy study of Follistim®in 172 chronic anovulatory women who failed to ovulate and/or conceive during clomiphene citrate treatment are summarized in Tables 3 and 4.

Table 3. Cumulative Ovulation Rates

Table 4. Cumulative Ongoing^1,2 Pregnancy Rates

Last reviewed on RxList: 11/17/2008
This monograph has been modified to include the generic and brand name in many instances.