Clinical pharmacology of recombinant human follicle-stimulating hormone (FSH). I. Comparative pharmacokinetics with urinary human FSH**Supported by grant GF 5007 from Ares Serono, Geneva, Switzerland.††Presented in part at the 9th Annual Meeting of the European Society of Human Reproduction and Embriology, Thessaloniki, Greece, June 27 to 30, 1993

Population Pharmacokinetic Analysis of Follicle-Stimulating Hormone During Ovarian Stimulation: Relation with Weight, Prolactin and Gene Polymorphism in THADA and ADIPOQ

BACKGROUND

Personalisation strategies of ovarian stimulation for in vitro fertilisation (IVF)/ intracytoplasmic sperm injection (ICSI) treatments using exogenous follicle-stimulating hormone (FSH) have been extensively studied over the past 20 years. This research aimed to develop a FSH population pharmacokinetic (PPK) model taking into account the contribution of gene polymorphisms in Chinese reproductive-age women.

METHODS

Data from 173 patients undergoing GnRH agonist down-regulation long protocols of IVF/ICSI treatment were collected. PPK analysis was subsequently conducted using the nonlinear mixed-effect model (NONMEM) software. Several covariates, including 18 single nucleotide polymorphisms, demographic factors and biological characteristics, were evaluated. The final PPK model was extensively validated using bootstrapping and normalised prediction error distribution, as well as external validation on an independent group of 35 patients.

RESULTS

FSH PPK was accurately described by a one-compartment model with first-order absorption. The typical population value of apparent clearance was estimated to be 0.81 L/h [relative standard errors (RSE) 5.3%] with an inter-individual variability (IIV) of 16.0%. The typical apparent distribution volume was 8.36 L (RSE 9.7%, 59.7% IIV), and the absorption rate constant was estimated to be 0.0444 h-1 (RSE 9.1%). Body weight, basal prolactin concentration and the gene ADIPOQ (rs1501299) showed a significant covariate effect on the FSH clearance rate and exposure concentration. Genotypes of THADA (rs12478601) significantly influenced the distribution volume. Simulation results indicated that patients with the TT genotype of THADA (rs12478601) required a longer time to reach steady state and had less fluctuation in FSH levels. Model evaluations showed that the final model accurately and precisely described the observed data and demonstrated effective prediction performance.

CONCLUSION

PPK models of FSH have been developed, which could potentially be used for FSH dosage individualisation in the clinical setting.

CLINICAL TRIAL REGISTRATION

This study has been registered with the Chinese Clinical Trials Registry (ChiCTR2100049142).

Use of new recombinant proteins for ovarian stimulation in ruminants

Currently, gonadotropin products (follicle stimulating hormone, FSH, and luteinizing hormone, LH) used in animal reproduction are produced by extraction and purification from abattoir-derived pituitary glands. This method, relying on animal-derived materials, carries the potential risk of hormone contamination and pathogen transmission. Additionally, chorionic gonadotropins are extracted from the blood of pregnant mares (equine chorionic gonadotropin; eCG) or the urine of pregnant women (human chorionic gonadotropin; hCG). However, recent advancements have introduced recombinant gonadotropins for assisted animal reproduction therapies. The traditional use of FSH for superovulation has limitations, including labor requirements and variability in superovulation response, affecting the success of in vivo (SOV) and in vitro (OPU/IVEP) embryo production. FSH treatment for superstimulation before OPU can promote the growth of a homogenous follicular population and the recovery of competent oocytes suitable for IVEP procedures. At present, a single injection of a preparation of long-acting bovine recombinant FSH (rFSH) produced similar superovulation responses resulting in the production of good-quality in vivo and in vitro embryos. Furthermore, the treatment with eCG at FTAI protocol has demonstrated its efficacy in promoting follicular growth, ovulation, and P/AI, mainly in heifers and anestrous cows. Currently, treatment with recombinant glycoproteins with eCG-like activity (r-eCG) have shown promising results in increasing follicular growth, ovulation, and P/AI in cows submitted to P4/E2 -based protocols. Bovine somatotropin (bST) is a naturally occurring hormone found in cows. Recombinant bovine somatotropin (rbST), produced through genetic engineering techniques, has shown potential in enhancing reproductive outcomes in ruminants. Treatment with rbST has been found to improve P/IA, increase donor embryo production, and enhance P/ET in recipients. The use of recombinant hormones allows to produce non-animal-derived products, offering several advantages in assisted reproductive technologies for ruminants. This advancement opens up new possibilities for improving reproductive efficiency and success rates in the field of animal reproduction.

Follicle-Stimulating Hormone Biological Products: Does Potency Predict Clinical Efficacy?

Follicle-stimulating hormone (FSH), together with luteinizing hormone (LH) and human chorionic gonadotropin (hCG), plays a fundamental role in human reproduction. The discovery of FSH and other gonadotropins was a defining moment in our understanding of reproduction and led to the development of many treatments for infertility. In this regard, exogenous FSH has been used to treat infertility in women for decades. Today, several recombinant and highly purified urinary forms of FSH are used in medically assisted reproduction (MAR). However, differences in the macro- and micro-heterogeneity of FSH result in a variety of FSH glycoforms, with glycoform composition determining the bioactivity (or potency), pharmacokinetic/pharmacodynamic (PK/PD) profiles, and clinical efficacy of the different forms of FSH. This review illustrates how the structural heterogeneity of FSH glycoforms affects the biological activity of human FSH products, and why potency does not predict effects in humans in terms of PK, PD, and clinical response.

Pharmacokinetics and Pharmacodynamics of Follicle-Stimulating Hormone in Healthy Women Receiving Single and Multiple Doses of Highly Purified Human Menotrophin and Urofollitrophin

BACKGROUND AND OBJECTIVE

Highly purified human menotrophin and urofollitrophin preparations obtained from human urine via a novel patented purification method have been tested over a timeframe of 14 years in the studies presented in this article. The objective of the studies was to investigate the pharmacokinetics and the pharmacodynamics of follicle-stimulating hormone (FSH) after single subcutaneous and intramuscular doses and multiple subcutaneous doses of the tested preparations in healthy fertile pituitary-suppressed women.

DESIGNS

We performed five open, randomised, crossover, single-dose bioequivalence and/or bioavailability studies and one open, multiple-dose, pharmacokinetics and pharmacodynamics study.

STUDY SUBJECTS AND TREATMENTS

The six studies included 121 healthy fertile women taking their usual combined oral contraceptives for 3 months before the study: Study 1: 300 international units (IU) of highly purified menotrophin as single subcutaneous and intramuscular doses. Study 2: 300 IU of highly purified menotrophin (test formulation vs. comparator) as single subcutaneous doses. Study 3: 300 IU of highly purified urofollitrophin (hp-FSH) (test formulation vs. comparator) as single subcutaneous doses. Study 4: 300 IU (2 × 150 IU vs. 4 × 75 IU) of hp-FSH as single subcutaneous doses. Study 5: 225 and 445 IU of hp-FSH as single subcutaneous doses. Study 6: daily 225 IU of hp-FSH as subcutaneous doses for 5 consecutive days.

MAIN OUTCOME MEASURES

The main outcome measures were the FSH pharmacokinetic parameters, estradiol concentrations, and the number and size of the follicles.

RESULTS

FSH after single subcutaneous and intramuscular injections of menotrophin or urofollitrophin attained a systemic peak (maximum) concentration (C _max) that was on average consistent throughout the first four studies and ranged from 4.98 to 7.50 IU/L. The area under the plasma concentration-time curve (AUC) from administration to the last observed concentration time t (AUC_t) ranged from 409.71 to 486.16 IU/L·h and the elimination half-life (t _½) ranged from 39.02 to 53.63 h. After multiple doses of urofollitrophin (225 IU) for 5 days, FSH attained a mean C _max of 14.93 ± 2.92 IU/L and had an AUC during the time interval τ between two consecutive doses at steady state (AUC_τ) of 322.59 ± 57.92 IU/L·h, which was similar to the mean AUC_t after a single subcutaneous dose of 225 IU of urofollitrophin in study 5 (306.82 ± 68.37 IU/L·h).

CONCLUSIONS

In our studies, the intramuscular and subcutaneous routes of menotrophin were equivalent; both menotrophin and urofollitrophin were bioequivalent to their marketed reference; FSH kinetic parameters following injection of urofollitrophin were dose proportional and independent from the administered concentration; and multiple doses of FSH increased estradiol levels and enhanced growth of follicles with a good dose-response correlation. Local tolerability was excellent throughout the six studies.

Immunoglobulin Fc Heterodimer Platform Technology: From Design to Applications in Therapeutic Antibodies and Proteins

The monospecific and bivalent characteristics of naturally occurring immunoglobulin G (IgG) antibodies depend on homodimerization of the fragment crystallizable (Fc) regions of two identical heavy chains (HCs) and the subsequent assembly of two identical light chains (LCs) via disulfide linkages between each HC and LC. Immunoglobulin Fc heterodimers have been engineered through modifications to the CH3 domain interface, with different mutations on each domain such that the engineered Fc fragments, carrying the CH3 variant pair, preferentially form heterodimers rather than homodimers. Many research groups have adopted different strategies to generate Fc heterodimers, with the goal of high heterodimerization yield, while retaining biophysical and biological properties of the wild-type Fc. Based on their ability to enforce heterodimerization between the two different HCs, the established Fc heterodimers have been extensively exploited as a scaffold to generate bispecific antibodies (bsAbs) in full-length IgG and IgG-like formats. These have many of the favorable properties of natural IgG antibodies, such as high stability, long serum half-life, low immunogenicity, and immune effector functions. As of July 2016, more than seven heterodimeric Fc-based IgG-format bsAbs are being evaluated in clinical trials. In addition to bsAbs, heterodimeric Fc technology is very promising for the generation of Fc-fused proteins and peptides, as well as cytokines (immunocytokines), which can present the fusion partners in the natural monomeric or heterodimeric form rather than the artificial homodimeric form with wild-type Fc. Here, we present relevant concepts and strategies for the generation of heterodimeric Fc proteins, and their application in the development of bsAbs in diverse formats for optimal biological activity. In addition, we describe wild-type Fc-fused monomeric and heterodimeric proteins, along with the difficulties associated with their preparations, and discuss the use of heterodimeric Fc as an alternative scaffold of wild-type Fc for naturally monomeric or heterodimeric proteins, to create Fc-fusion proteins with novel therapeutic modality.

Clinical Applications of Gonadotropins in the Male

The pituitary gonadotropins, luteinizing hormone (LH), and follicle-stimulating hormone (FSH) play a pivotal role in reproduction. The synthesis and secretion of gonadotropins are regulated by complex interactions among several endocrine, paracrine, and autocrine factors of diverse chemical structure. In men, LH regulates the synthesis of androgens by the Leydig cells, whereas FSH promotes Sertoli cell function and thereby influences spermatogenesis. Gonadotropins are complex molecules composed of two subunits, the α- and β-subunit, that are noncovalently associated. Gonadotropins are decorated with glycans that regulate several functions of the protein including folding, heterodimerization, stability, transport, conformational maturation, efficiency of heterodimer secretion, metabolic fate, interaction with their cognate receptor, and selective activation of signaling pathways. A number of congenital and acquired abnormalities lead to gonadotropin deficiency and hypogonadotropic hypogonadism, a condition amenable to treatment with exogenous gonadotropins. Several natural and recombinant preparations of gonadotropins are currently available for therapeutic purposes. The difference between natural and the currently available recombinant preparations (which are massively produced in Chinese hamster ovary cells for commercial purposes) mainly lies in the abundance of some of the carbohydrates that conform the complex glycans attached to the protein core. Whereas administration of exogenous gonadotropins in patients with isolated congenital hypogonadotropic hypogonadism is a well recognized therapeutic approach, their role in treating men with normogonadotropic idiopathic infertility is still controversial. This chapter concentrates on the main structural and functional features of the gonadotropin hormones and how basic concepts have been translated into the clinical arena to guide therapy for gonadotropin deficit in males.

Phase I, two-way, crossover study to demonstrate bioequivalence and to compare safety and tolerability of single-dose XM17 vs Gonal-f® in healthy women after follicle-stimulating hormone downregulation

BACKGROUND

XM17 is a recombinant human follicle-stimulating hormone (rhFSH) intended mainly for use in controlled ovarian hyperstimulation and the treatment of anovulation. The purpose of the current study was to establish bioequivalence, safety and tolerability of single 300-IU subcutaneous (sc) doses of XM17 to that of the reference follitropin alfa (Gonal-f(®)) in healthy young women.

METHODS

This open-label, Phase I, single-dose, single-center, two-way crossover study was conducted from February to May 2009. Thirty-six women aged 18-39 years were included, with a study duration of ~27 days per participant. After endogenous FSH downregulation with goserelin (3.6 mg) on study Day 0, XM17 and Gonal-f(®) were administered on Days 11 and 19 in random sequence. Frequent serum samples were drawn for standard pharmacokinetics until 168 h postdosing. Laboratory values, adverse events (AEs) and local tolerability were assessed throughout the study period. Primary endpoints included Cmax and AUC0-t. Secondary endpoints included additional pharmacokinetic (PK) parameters, safety and tolerability.

RESULTS

Ratios of XM17 to Gonal-f(®) for Cmax and AUC0-t equaled 1.017 (90 % confidence interval [CI]: 0.958, 1.080) and 1.028 (90 % CI: 0.931, 1.134), respectively, with the CIs contained within the predefined interval (0.8, 1.25). Ratios for AUC0-168h, AUC0-∞ and t1/2 were also ~1, and no difference in tmax was detected. Both XM17 and Gonal-f(®) were well tolerated, with no detectable anti-FSH antibodies, serious AEs or AEs leading to discontinuation or dose reduction.

CONCLUSIONS

PK bioequivalence of single 300-IU sc doses of XM17 to the reference product Gonal-f® was statistically demonstrated. XM17 was well tolerated both systemically and locally.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT02592031 ; date of registration: 28 October, 2015.

Abdominal mesotherapy injection extended the absorption of follicle-stimulating hormone

Abdominal mesotherapy injection of recombinant human FSH (rhFSH) was well tolerated with increased net absorption (AUC0-∞ 4,655.3 IU·h/L and t1/2 247.6 h) up to 360 hours compared with those of 120 hours (AUC0-∞ 1,915.7 IU·h/L and t1/2 101.8 h). The extended absorption of rhFSH suggests that abdominal mesotherapy injection mode be considered for future administration of rhFSH in controlled ovarian hyperstimulation.

The absorption and uptake of recombinant human follicle-stimulating hormone through vaginal subcutaneous injections--a pharmacokinetic study

BACKGROUND

Follicle stimulating hormone (FSH) has been routinely used for ovulation induction. Because of rapid clearance of the hormone, FSH is commonly administered by daily intramuscular or subcutaneous injections in in-vitro fertilization (IVF). To reduce the number of visits to the clinic, an intermittent vaginal injection of rhFSH every 3 days employing the concepts of mesotherapy and uterine first-pass effect was invented and has successfully been applied in women receiving IVF treatment. This study was designed to monitor the pharmacokinetic pattern of rhFSH administered vaginally.

METHODS

Twelve healthy women with regular ovulatory cycles were recruited. All volunteers received gonadotrophin-releasing hormone agonist to suppress pituitary function and were assigned to receive single dose recombinant human FSH (rhFSH, Puregon 300) either using conventional abdominal subcutaneous injection or vaginal subcutaneous injection in a randomized cross-over study. Serum samples were collected at pre- scheduled time intervals after injections of rhFSH to determine immunoreactive FSH levels. Pharmacokinetic parameters characterizing rate [maximal plasma concentrations (Cmax) and time of maximal plasma concentrations (tmax)] and extent [area under the plasma concentration-time curve (AUC) and clearance] of absorption of rhFSH were compared.

RESULTS

Vaginal injection of rhFSH was well tolerated and no drug-related adverse reaction was noted. Our analysis revealed that tmax was significantly earlier (mean 6.67 versus 13.33 hours) and Cmax was significantly higher (mean 17.77 versus 13.96 IU/L) in vaginal versus abdominal injections. The AUC(0-infinity) was 1640 versus 1134 IU hour/L in vaginal and abdominal injections, respectively. Smaller plasma elimination rate constant (0.011 versus 0.016 hour-1), longer mean residence time (106.58 versus 70.47 hours), and slower total body clearance (292.2 versus 400.1 mL/hour) were also found in vaginal injection.

CONCLUSION

The vaginal injection mode elicited a rapid and highly extended absorption of rhFSH injected compared to conventional abdominal injection. These data indicate that the rate and extent of FSH absorption from the injection site can vary depending on the route of the FSH administration.

Administration of follitropin alfa and lutropin alfa combined in a single injection: a feasibility assessment

BACKGROUND

Gonadotrophins are routinely administered in assisted reproductive technology (ART) treatment protocols. Recombinant human follicle-stimulating hormone (r-hFSH; follitropin alfa) and recombinant human luteinizing hormone (r-hLH; lutropin alfa) can be administered individually or in a fixed combination. The ability to vary the FSH to LH dose ratio in a single injection without compromising the bioactivity of either gonadotrophin or generating losses of active principle is important for physicians and patients alike.

METHODS

This study investigated whether follitropin alfa (GONAL-f ), as lyophilized powder for reconstitution or solution from the GONAL-f (filled-by-mass [FbM]) Prefilled Pen, could be used to reconstitute Pergoveris TM (follitropin alfa/lutropin alfa 150 IU/75 IU) lyophilized powder. In Ratio Groups 1 and 2, the r-hFSH:r-hLH ratio was 3:1; in Ratio Groups 3 and 4, the ratios of r-hFSH:r-hLH were 5:1 and 8:1, respectively. The protein content and bioactivity of each mixed solution were evaluated. The r-hFSH and r-hLH content was determined using reverse-phase high performance liquid chromatography. The biological activity of r-hFSH and r-hLH was assessed using the Steelman-Pohley and Van Hell in vivo bioassays in rats, respectively.

RESULTS

Follitropin alfa/lutropin alfa 150 IU/75 IU lyophilized powder could be successfully mixed with follitropin alfa 75 IU FbM solution that was either reconstituted from lyophilized powder or injected directly from the prefilled pen to create solutions with ratios of r-hFSH and r-hLH from 3:1 to 8:1. The measured content of r-hFSH and r-hLH corresponded favourably with the target protein content in Ratio Groups 1-4. The in vivo target and measured bioactivity of r-hFSH and r-hLH were also closely matched in all Ratio Groups.

CONCLUSION

Follitropin alfa lyophilized powder or solution can be accurately mixed with follitropin alfa/lutropin alfa 150 IU/75 IU lyophilized powder to enable physicians to administer ratios of r-hFSH and r-hLH in the IU range from 3:1 to 8:1. Mixing of recombinant formulations offers flexibility for patients receiving follitropin alfa and lutropin alfa for ART protocols in clinical practice.

Follicle-stimulating hormone in clinical practice: an update

Follicle-stimulating hormone (FSH), a glycoprotein produced by the anterior pituitary gland, plays an important role in the regulation of fertility in both men and women. FSH is used clinically to treat women with anovulatory infertility, for controlled ovarian stimulation in women being treated with assisted reproductive technologies (ART), and in the treatment of male hypogonadotrophic hypogonadism. Urine-derived gonadotropin preparations containing variable amounts of FSH together with urinary proteins have been available for many years. More recently, FSH preparations produced using recombinant DNA technology have become available. Recombinant FSH has a high specific activity, high purity, and guaranteed consistency among batches. Two recombinant FSH preparations have been available for clinical use for some years: follitropin-alpha and follitropin-beta. The continuing development of recombinant FSH has recently resulted in a new presentation (follitropin-alpha filled by mass [FbM]). This product can be filled by mass (microg) with an activity (IU), reflecting exceptional consistency as a result of refinement and improvement in the manufacturing process, allowing the clinician to deliver a guaranteed dose of FSH. Experience with recombinant FSH in the treatment of male hypogonadotrophic hypogonadism is limited, but the available data suggest that recombinant FSH has a similar efficacy to urine-derived preparations (urofollitropin). In patients with WHO group I anovulatory infertility, the use of recombinant FSH to stimulate follicular development is effective and well tolerated. In patients with WHO group II anovulation, protocols based on recombinant FSH are more effective than conventional protocols using urofollitropin. Comparative studies and a meta-analysis have shown that recombinant FSH is more effective than urofollitropin for controlled ovarian stimulation in women undergoing ART. Pharmacoeconomic modeling indicates that follitropin-alpha is more cost effective than urofollitropin in a range of different healthcare systems. The available evidence from comparative studies of the two recombinant FSH preparations suggests that follitropin-alpha may have an advantage over follitropin-beta in terms of efficacy. Follitropin-alpha is superior to follitropin-beta in terms of local tolerability. Recent preliminary studies suggest an efficacy advantage for follitropin-alpha FbM compared with standard follitropin-alpha. The FbM presentation appears to represent an advance on standard preparations of recombinant FSH in terms of consistency and clinical efficacy.

Pharmacokinetic and pharmacodynamic considerations in the development of therapeutic proteins

With an increasing number of therapeutic proteins moving into preclinical and clinical development, pharmacokinetic factors play an important role in the development of these macromolecules. It is also important that the pharmacokinetic evaluation of these compounds be done as accurately as possible. For macromolecules, evaluation of pharmacokinetic parameters is often complicated by a number of factors. Bioanalytical methods are essential for any pharmacokinetic study, but for many therapeutic proteins the immunoassay and bioassay methodologies are often nonspecific and sometimes the estimation of pharmacokinetic parameters becomes assay dependent. In vivo binding proteins, metabolites and antibody formation may also interfere with bioanalytical methodologies and thus may have significant impact on the pharmacokinetics of therapeutic proteins. There are also difficulties in identifying and quantifying metabolites as well as the binding of therapeutic proteins to endogenous proteins. Some macromolecules exhibit species specificity that complicates the preclinical pharmacological and toxicological evaluation of these compounds. Antibody formation is a particular problem in the preclinical evaluation of therapeutic proteins. Changes in structure or sequence of protein molecules (glycosylation or pegylation) may cause changes in the pharmacokinetics of these compounds. The size of therapeutic proteins may become a hindrance for absorption. Low absorption of intact molecules across biological membranes frequently occurs. Other factors that may affect the pharmacokinetics of a therapeutic protein are immunogenicity, presence of endogenous protein, time of drug administration, and rate and site of drug delivery. The relationship between pharmacokinetics and pharmacodynamics of therapeutic proteins is complex and in most cases is unclear. In many cases the mechanism and site of action are unknown for these compounds.

Recruitment of follicles by recombinant human follicle-stimulating hormone commencing in the luteal phase of the ovarian cycle

OBJECTIVE

To investigate, in patients who previously had a suboptimal ovarian stimulation cycle, the benefit of starting ovarian stimulation before the onset of menses.

DESIGN

Prospective, randomized, controlled study.

SETTING

A tertiary referral center for infertility treatment.

PATIENT(S)

Forty patients undergoing IVF or GIFT from whom only 3-6 oocytes were retrieved in their last cycle.

INTERVENTION(S)

Recombinant human FSH was administered before the onset of the menstrual period (experimental group) or in the early follicular phase after the onset of menses (control group).

MAIN OUTCOME MEASURE(S)

The number of oocytes retrieved.

RESULT(S)

Patients in the experimental group were ready for oocyte retrieval on menstrual cycle day 11 instead of cycle day 14. The number of oocytes retrieved was not significantly different between the two groups.

CONCLUSION(S)

Poor responders do not benefit from commencing recombinant human FSH therapy in the luteal phase.

Pharmacokinetic and pharmacodynamic interactions between recombinant human luteinizing hormone and recombinant human follicle-stimulating hormone

OBJECTIVE

To assess the pharmacokinetics of a recombinant human LH preparation and its pharmacokinetic and pharmacodynamic interactions with recombinant human follicle-stimulating hormone (FSH).

DESIGN

Prospective, randomized cross-over study.

SETTING

Phase I clinical research environment.

PATIENT(S)

Twelve healthy pituitary down-regulated females.

INTERVENTION(S)

Subjects received 150 IU of s.c. recombinant human LH and FSH, either alone or in combination, followed by recombinant human LH and FSH once daily for 7 days.

MAIN OUTCOME MEASURE(S)

Pharmacokinetic parameters, ovarian follicle development.

RESULT(S)

No pharmacokinetic interaction between recombinant human LH and FSH was observed, with no significant difference in baseline-corrected maximal observed concentration over baseline, area under the concentration-time curve from t = 0 to t = 24 hours, or time to maximal concentration after single doses alone or in combination. After daily administration, the mean accumulation ratio was 1.6 for LH and 2.9 for FSH, with absorption and terminal phase half-life estimates of 4 and 11 hours for LH and 8 and 16 hours for FSH, respectively. Combined administration of FSH and LH for 7 days was effective in stimulating ovarian follicular development and steroidogenesis, with large interindividual variability related to ovarian sensitivity.

CONCLUSION(S)

A new recombinant human LH preparation has a low accumulation ratio at steady-state and no pharmacokinetic or pharmacodynamic interactions with recombinant human FSH.

Clinical pharmacology of recombinant human luteinizing hormone: Part I. Pharmacokinetics after intravenous administration to healthy female volunteers and comparison with urinary human luteinizing hormone

OBJECTIVE

To assess the pharmacokinetics after i.v. administration of a recombinant human LH and to compare them to those of a reference hMG preparation containing urinary human LH.

DESIGN

Prospective, dose-escalating, cross-over study.

SETTING

Phase I clinical research environment.

PATIENT(S)

Twelve healthy pituitary down-regulated females.

INTERVENTION(S)

Subjects received single i.v. doses of 300, 10,000, and 40,000 IU of recombinant human LH, followed by a single i.v. dose of 300 IU of hMG, all separated by 1 week.

MAIN OUTCOME MEASURE(S)

Pharmacokinetic parameters.

RESULTS

For both preparations, LH serum levels were well described by similar biexponential models. The pharmacokinetics of recombinant human LH were linear over the 300 to 40,000 IU range. After a rapid distribution phase with an initial half-life of 1 hour, both recombinant human LH and urinary human LH were eliminated with a terminal half-life of 10-12 hours. Total serum clearance was 1.7 L/h with < 4% and 30% of the dose being eliminated in the urine for recombinant human LH and urinary human LH, respectively. The volume of distribution at steady-state was approximately 10 L. Irrespective of the dose, recombinant human LH was well tolerated.

CONCLUSION(S)

The pharmacokinetics of recombinant human LH are linear with dose and similar to those of urinary human LH.

Clinical pharmacology of recombinant human luteinizing hormone: Part II. Bioavailability of recombinant human luteinizing hormone assessed with an immunoassay and an in vitro bioassay

OBJECTIVE

To assess the single-dose pharmacokinetics of a recombinant human LH preparation administered by the i.v., i.m., and s.c. route.

DESIGN

Prospective, randomized cross-over study.

SETTING

Phase I clinical research environment.

PATIENT(S)

Twelve healthy pituitary down-regulated females.

INTERVENTION(S)

Subjects received single i.v., i.m., and s.c. doses of 10,000 IU of recombinant human LH, each separated by 1 week.

MAIN OUTCOME MEASURE(S)

Pharmacokinetic parameters.

RESULT(S)

After single i.v. administration, the pharmacokinetics were described by a two-compartment model, after i.m. or s.c. administration, by a one-compartment model with zero order absorption and a lag time. Using the immunoassay, after i.v. administration initial half-life was 1 hour and terminal half-life was 10 hours (half-life was prolonged after extravascular administration, suggesting rate-limiting absorption). Total serum clearance was 2.6 L/h, and steady, state volume of distribution was 14 L. Observed Cmax, after i.m. and s.c. administration, was 43 IU/L with median tmax of 9 hours (i.m.) and 5 hours (s.c.). Bioavailability was 0.54 (i.m.) and 0.56 (s.c.). The pharmacokinetics of LH are comparable using an in vitro bioassay.

CONCLUSION(S)

The terminal half-life of recombinant human LH is around 12 hours and is slightly prolonged after extravascular administration. The pharmacokinetics are similar after i.m. and s.c. injection, and one-half the administered dose is available systemically.

Recombinant technique and gonadotropins production: new era in reproductive medicine

OBJECTIVE

To review current knowledge regarding recombinant DNA technology and its safety and efficacy in relation to recombinant gonadotropin production.

DATA IDENTIFICATION AND SELECTION

Studies that relate specifically to recombinant DNA technology, method of laboratory production, and the clinical aspects of using recombinant gonadotropins were identified through literature and Medline searches.

RESULTS

Recent developments in recombinant DNA technology have resulted in a rapidly expanding range of new diagnostic and therapeutic opportunities. This technology paves the way to the identification, isolation, cloning, and production of specific proteins. Recently, recombinant human gonadotropins became available for clinical use. The pharmacokinetics, receptor availability, pharmacodynamics, and safety were studied extensively and the drugs were found to be identical if not superior to urinary gonadotropins that have been used in reproductive medicine for the last 30 years. It is clear today that the use of recombinant human gonadotropins is expected to provide better batch-to-batch consistency, steady supply, and most importantly, a purified compound with high specific activity, which accounts for >99% of the preparation's protein content, allowing SC administration.

CONCLUSION

There is no doubt that recombinant gonadotropins produced by genetic engineering technology are here to stay and will represent an important treatment modality in various fertility disturbances.

The relevance of pharmacokinetics in the development of biotechnology products

Biotechnology derived medicines will have an increasing impact not only upon medical practice but also upon the working lives of many pharmaceutical scientists. Whilst such medicines may be viewed as highly sophisticated to the clinician and scientist, the computer will still rightly demand that they are both efficacious and safe. Impacting as it does upon all phases of drug development and facilitating quantitative relationship between administered dose and systemic drug concentration, pharmacokinetics has an important role to play in the development of all medicines. Bioanalysis is an essential prelude to any pharmacokinetic investigation. For many biotechnology products the immunoassay and bioassay methodologies employed are often relatively non-specific and imprecise and yield assay dependent pharmacokinetic parameters. Other factors may also confound the pharmacokinetic evaluation of biotechnological products. In vivo binding proteins (including antibodies) may not only interfere with bioanalytical methodology but also have a significant effect on the pharmacokinetics and biological activity of certain macromolecules. Antibody formation is a particular problem in the preclinical evaluation of human proteins. Unlike most conventional pharmaceuticals, the rate and time of delivery into the systemic circulation is a fundamental component of the biological activity of many biological molecules.

Pharmacokinetics of follicle-stimulating hormone: clinical significance

OBJECTIVE

To review studies that examine the pharmacokinetics and pharmacodynamics of endogenous, as well as several exogenous FSH preparations.

DESIGN

Related studies were identified through a computerized bibliographic search.

PATIENTS

Initial pharmacodynamic studies were done in animal models and in women and men with either hypogonadotropic hypogonadism or suppressed hypothalamic-pituitary-gonadal axis. More recent studies evaluated FSH pharmacokinetics during ovulation induction treatment in women with normal ovulatory cycles or polycystic ovarian syndrome.

RESULTS

Various types of FSH exist according to their sialic acid content. High estrogen levels induce the secretion of less sialylated molecules with higher receptor affinity and an increased clearance rate. It appears that there is a threshold FSH level that should be reached to achieve an ovarian response. A very narrow range exists between the threshold and ceiling level for monofollicular growth. This threshold level is surpassed intentionally during IVF treatment cycles to induce multiple follicular recruitment. The threshold level can change under situations such as polycystic ovaries, perimenopause, oral contraceptives, and GnRH analogue treatment.

CONCLUSIONS

To avoid the risk of ovarian hyperstimulation syndrome and multiple pregnancies, careful adjustments of serum FSH levels should be made by fine dosage modifications. By monitoring FSH levels and using less sialylated preparations, the efficacy of the treatment probably will improve.

Superovulation before IVF by recombinant versus urinary human FSH (combined with a long GnRH analog protocol): a comparative study

PURPOSE

Gonal-F (Serono, Aubonne, Switzerland) is a recombinant human follicle stimulating hormone (FSH) synthesized in vitro by cells into which genes encoding for FSH subunits have been inserted. This preparation exhibits physiochemical, immunological, and pharmacological properties that bear great similarity to those of native human FSH. It has a high specific activity and can be administered subcutaneously. To compare the efficacy and safety of Gonal-F with those of urinary human FSH (Metrodin; Serono) in achieving superovulation for IVF purposes in a prospective, randomized study.

METHODS

Twenty infertile patients (normo-ovulatory healthy women) were recruited for the study and allocated at random to the Gonal-F or Metrodin groups. The treatment protocol consisted of pituitary down regulation by GnRH analog (Buserelin; Hoechst, Frankfurt, Germany) employing the "long" protocol initiated at the mid-luteal phase (900 micrograms/day, intranasal administration). Gonal-F (SC) or Metrodin (IM) was injected daily (225 IU/day) starting on cycle day 3. Dose adjustment was performed, when necessary, from cycle day 7.

RESULTS

Of the 20 cycles analyzed, none was canceled due to poor response. No cases of adverse effects (including local intolerance) or ovarian hyperstimulation syndrome were recorded in either group. They did not differ significantly in the following treatment-dependent variables: hormone profile, duration of FSH treatment, total FSH dose required to achieve follicular maturation, and the number of oocytes retrieved, fertilized, and replaced.

CONCLUSIONS

These preliminary data concur with previous studies in demonstrating that Gonal-F is as effective and safe as Metrodin (when given in combination with a "long" protocol of GnRH analog) in inducing controlled ovarian hyperstimulation for IVF purposes. Its mode of administration (SC instead of IM) offers an additional advantage over the urinary human FSH.