Pharmacokinetics of Follicle-Stimulating Hormone: Clinical Significance

Biological Assay to Determine Gonadotropin Potency: From In Vivo to In Vitro Sustainable Method

Various preparations of follicle-stimulating hormone (FSH) are commercially available; however, they differ in glycoforms composition and purity owing to their respective sources. Additional chemical/physical changes can also be introduced during manufacturing and can impact their biological activity (biopotency), which is routinely assessed using an in vivo bioassay (Steelman-Pohley). This study aimed to determine whether an in vitro bioassay could assess biopotency by distinguishing between r-hFSH chemical/physical variants with similar ability to the in vivo bioassay. The specific activity (units of biological activity per mg of product) of variants of r-hFSH generated through enrichment (acidic/basic), stress (oxidative/acidic pH) and enzymatic treatment (desialylation and desialylation/degalactosylation) was compared using the in vivo and in vitro bioassays. The in vitro bioassay reliably detected potential chemical/physical modifications in r-hFSH variants that may impact biopotency. Overall, the methods demonstrated a comparable ability to detect changes in specific activities due to chemical/physical differences in r-hFSH variants. These data indicate that the in vitro bioassay is suitable to replace the in vivo bioassay.

Ovarian Folliculogenesis and Uterine Endometrial Receptivity after Intermittent Vaginal Injection of Recombinant Human Follicle-Stimulating Hormone in Infertile Women Receiving In Vitro Fertilization and in Immature Female Rats

The uterine first-pass effect occurs when drugs are delivered vaginally. However, the effect of vaginally administered recombinant human follicle-stimulating hormone (rhFSH) on ovarian folliculogenesis and endometrial receptivity is not well established. We aimed to compare the efficacy of rhFSH administered vaginally and abdominally in clinical in vitro fertilization (IVF) treatment, pharmacokinetic study, and animal study. In IVF treatment, the number of oocytes retrieved, endometrial thickness and uterine artery blood perfusion were not different between women who received the rhFSH either vaginally or abdominally. For serum pharmacokinetic parameters, significantly lower Tmax, clearance, and higher AUC and T_1/2_elimination of rhFSH were observed in women who received rhFSH vaginally, but urine parameters were not different. Immature female rats that received daily abdominal or vaginal injections (1 IU twice daily for 4 days) or intermittent vaginal injections (4 IU every other day for two doses) of rhFSH had more total follicles than the control group. In addition, the serum progesterone and progesterone receptors in the local endometrium were significantly higher in the groups treated with intermittent abdominal or vaginal injection of rhFSH, compared with those who recieved daily injection. In summary, vaginal administration of rhFSH may provide an alternative treatment regimen in women receiving IVF.

The impact of polycystic ovary syndrome and body mass index on the absorption of recombinant human follicle stimulating hormone

PURPOSE

Women with polycystic ovary syndrome (PCOS) have an increased ovarian responsiveness to exogenous recombinant follicle stimulating hormone (rFSH) but also have high rates of obesity, which is known to affect serum FSH concentrations following exogenous injection. The purpose of this study was to compare rFSH absorption and ovarian response between lean and overweight/obese PCOS subjects and normo-ovulatory controls.

METHODS

Fourteen women with PCOS aged 18-42 years old with a BMI of 18.5-24.9 kg/m2 (normal) or 25.0-40.0 kg/m2 (overweight/obese) and eleven normo-ovulatory controls matched by age and BMI were included. After downregulation with oral contraceptives, participants were administered a single subcutaneous injection of 225 IU rFSH and underwent serial blood draws over 72 h.

RESULTS

Lean PCOS subjects exhibited a significantly higher area under the curve (AUC) of baseline-corrected serum FSH over 72 h when compared with overweight/obese PCOS subjects (183.3 vs 139.8 IU*h/L, p = 0.0002), and lean, normo-ovulatory women had a significantly higher AUC FSH when compared with overweight/obese, normo-ovulatory women (193.3 vs 93.8 IU*h/L, p < 0.0001). Within overweight/obese subjects, those with PCOS had a significantly higher AUC FSH compared with normo-ovulatory controls (p = 0.0002). Lean PCOS subjects similarly had the highest AUC of baseline-corrected estradiol (6095 pg h/mL), compared with lean normo-ovulatory subjects (1931 pg h/mL, p < 0.0001) and overweight/obese PCOS subjects (2337 pg h/mL, p < 0.0001).

CONCLUSION

Lean PCOS subjects exhibited significantly higher baseline-corrected FSH and estradiol levels following rFSH injection compared with overweight/obese PCOS subjects with similar ovarian reserve markers. Amongst overweight/obese subjects, those with PCOS had significantly higher FSH and E2 levels when compared with normo-ovulatory controls.

Fertility drug therapies: past, present, and future

Throughout the last 30 years there has been an evolution of drug therapies aimed at the treatment of infertility. These agents primarily address the induction of ovulation or enhancing ovulation by allowing more oocytes to mature simultaneously. As this evolution has progressed, drugs have moved away from human products to the advent of the recombinant or genetically engineered technology. The drugs have not cured infertility, but they have affected positively the quest of families confronted by infertility.