Pharmacokinetics of human chorionic gonadotropin after i.m. administration in goats (Capra hircus).

The present investigation addresses the pharmacokinetics of human chorionic gonadotropin (hCG), intramuscularly (i.m.) administered to goats. Nine pluriparous does of the Boer goat breed, 2-6 years of age and weighing 45-60 kg, were administered 500 IU hCG (2 ml Chorulon) deep into the thigh musculature 18 h after superovulatory FSH treatment. Blood samples were drawn from the jugular vein at 2  h intervals for the first 24h, at 6 h intervals until 42 h, and at 12 h intervals until 114 h after administration. After centrifugation, plasma hCG concentrations were determined by electrochemiluminescence immunoassay. Pharmacokinetical parameters were as follows: lag time, 0.4 (s.e.m. 0.1) h; absorption rate constant, 0.34 (s.e.m. 0.002) h; absorption half-life, 2.7 (s.e.m. 0.5) h; elimination rate constant, 0.02 (s.e.m. 0.002) h; biological half-life, 39.4 (s.e.m. 5.1) h; and apparent volume of distribution, 16.9 (s.e.m. 4.3) l. The plasma hCG profile was characterized by an absorption phase of 11.6 (s.e.m. 1.8) h and an elimination phase of 70.0 (s.e.m. 9.8) h, with considerable individual variation in bioavailability and pharmacokinetical parameters. Biological half-life was negatively correlated (P<0.05) with peak concentration (r=-0.76), absorption rate constant (r=-0.78), and elimination rate constant (r=-0.87). The results indicate that after rapid absorption, hCG remains in the circulation for an extended period. This has to be taken into account when assessing the stimulatory response to hCG treatment on an ovarian level.

Randomized Pharmacokinetic Study of a Highly Purified Human Chorionic Gonadotropin and of a Recombinant Human Chorionic Gonadotropin Following Single Subcutaneous Administration in Healthy Women.

BACKGROUND AND OBJECTIVES: Exogenous human chorionic gonadotropin (hCG) acts on the final phase of the follicle maturation. Choriomon®, a highly purified hCG formulation, is approved in many European and extra-European countries for the induction of ovulation after stimulation of follicular development. The present study compares hCG bioavailability of Choriomon® (Test product) versus a recombinant hCG preparation (Ovitrelle®; Reference product). METHODS: In this randomized, two-way cross-over study, 26 healthy women received a single dose of Choriomon® (10,000 IU) and Ovitrelle® (250 µg; 6500 IU) by subcutaneous injection. hCG was determined in serum up to 192 h post-dose. Dose-normalized peak concentration (Cmax) and area under the concentration-time curve up to the time of the last quantifiable concentration (AUC0-t) and extrapolated to infinity (AUC0-∞) were calculated and compared between the two treatments. RESULTS: Serum hCG concentrations increased rapidly with a very similar pharmacokinetic curve for the two products. The test/reference geometric means ratio (GMR) for AUC0-t and AUC0-∞ corresponded to 121.31 and 119.81%, and the upper limits of the 90% confidence intervals (CIs) (130.21% and 128.51%, for AUC0-t and AUC0-∞, respectively) exceeded the 125% bioequivalence threshold. Cmax GMR was 146.89%, indicating a rate of hCG absorption approximately 50% greater for the test product (90% CI 132.30-163.10). Half-life (t1/2) was very similar (36.77 ± 5.11 h and 38.63 ± 6.08 h), whereas time to achieve Cmax (tmax) significantly differed, with median values of 16 h and 24 h for Choriomon® and Ovitrelle®, respectively, (p = 0.0023). CONCLUSIONS: The differences between Choriomon® and Ovitrelle® pharmacokinetic parameters can be ascribed to the different raw source of the products and are reflected in the approved dose regimens of the two hCG formulations. The observed lack of bioequivalence between the two compounds at the given doses is not clinically relevant, as results from Phase III studies indicated similar clinical efficacy and safety. The safety data are in line with the known safety profile of the two products. GOV REGISTRATION NO: NCT03735030.

Current opinion on use of luteinizing hormone supplementation in assisted reproduction therapy: an Asian perspective.

LH and FSH have complementary functions in ensuring optimal oocyte maturation and ovulation. In women undergoing assisted reproduction technology protocols with gonadotrophin-releasing hormone analogues, LH and FSH concentrations are reduced. While FSH use in assisted reproduction technology is well established, there is no published consensus on the need for exogenous LH in Asian patients. Having reviewed the concept of the LH therapeutic window and differences between recombinant human LH (r-HLH) and human menopausal gonadotrophin, a consensus was reached on which patient subgroups may benefit from LH supplementation. Adjuvant r-HLH gives clinicians precise control over the dose of LH bioactivity administered to target the therapeutic window. The use of r-HLH is recommended in women with poor response in a previous cycle or suboptimal follicular progression in a current cycle by day 6-8 of stimulation. r-HLH should also be considered in women at risk of suboptimal response, specifically age > 35 years. Other risk markers that suggest the need for LH supplementation, which include baseline/day-6 serum LH and anti-Müllerian hormone concentrations, antral follicle count and LH polymorphisms require further research and verification. For measurement of LH response adequacy, the monitoring of follicular progression, oestradiol concentrations and endometrial thickness is recommended.

First-in-human trial assessing the pharmacokinetic-pharmacodynamic profile of a novel recombinant human chorionic gonadotropin in healthy women and men of reproductive age.

The purpose of this first-in-human trial was to examine the safety, pharmacokinetics (PK), and pharmacodynamics (PD) of a novel recombinant human chorionic gonadotropin (rhCG; FE 999302, choriogonadotropin beta) to support its clinical development for various therapeutic indications. The single and multiple dose PK of choriogonadotropin beta (CG beta) were evaluated in women and the single dose PK and PD of CG beta were compared to those of CG alfa in men. CG beta was safe and well-tolerated in all 84 healthy subjects. In women, the area under the curve (AUC) and the peak serum concentration (Cmax ) increased approximately dose proportionally following single and multiple doses of CG beta. The apparent clearance (CL/F) was ~ 0.5 L/h, the mean terminal half-life (t½ ) ~ 45 h and the apparent distribution volume (Vz /F) ~ 30 L. After single administration in men, the mean AUC was 1.5-fold greater for CG beta than for CG alfa. Mean Cmax and Vz /F were comparable for the 2 preparations. In accordance with the differences in AUC, the CL/F was lower for CG beta (CL/F 0.5 vs. 0.8 L/h), explained by a longer t½ (47 vs. 32 h). Serum testosterone levels induced by a single dose rhCG reflected the PK profiles with a slight delay, resulting in 59% higher AUC for CG beta. The PK parameters for CG beta were comparable in men and in women. In conclusion, the PK differs between the two rhCG preparations, causing higher exposure and a higher PD response for CG beta, which may require relatively lower therapeutic doses.

Predictive values of hCG clearance for risk of methotrexate resistance in low-risk gestational trophoblastic neoplasias.

BACKGROUND: Early identification of patients at high risk for chemoresistance among those treated with methotrexate (MTX) for low-risk gestational trophoblastic neoplasia (GTN) is needed. We modeled human chorionic gonadotropin (hCG) decline during MTX therapy using a kinetic population approach to calculate individual hCG clearance (CL(hCG)) and assessed the predictive value of CL(hCG) for MTX resistance. PATIENTS AND METHODS: A total of 154 patients with low-risk GTN treated with 8-day MTX regimen were retrospectively studied. NONMEM was used to model hCG decrease equations between day 0 and day 40 of chemotherapy. Receiver operating characteristic curve analysis defined the best CL(hCG) threshold. Univariate/multivariate survival analyses determined the predictive value of CL(hCG) and compared it with published predictive factors. RESULTS: A monoexponential equation best modeled hCG decrease: hCG(t) = 3900 x e(-0.149 x t). Median CL(hCG) was 0.57 l/day (quartiles: 0.37-0.74). Only choriocarcinoma pathology [yes versus no: hazard ratio (HR) = 6.01; 95% confidence interval (CI) 2.2-16.6; P < 0.001] and unfavorable CL(hCG) quartile (< or =0.37 versus >0.37 l/day: HR = 6.75; 95% CI 2.7-16.8; P < 0.001) were significant independent predictive factors of MTX resistance risk. CONCLUSION: In the second largest cohort of low-risk GTN patients reported to date, choriocarcinoma pathology and CL(hCG) < or =0.37 l/day were major independent predictive factors for MTX resistance risk.

Comparative Pharmacokinetics, Bioequivalence and Safety Study of Two Recombinant Human Chorionic Gonadotropin Injections in Healthy Chinese Subjects.

OBJECTIVE: To evaluate the pharmacokinetics (PK), bioequivalence and safety profile of the recombinant human chorionic gonadotropin (r-hCG) injection formulation LZM003 (test drug) comparing with that of Ovidrel® (reference drug) in healthy Chinese subjects. METHODS: This is a randomized, single-blind, single-dose, two-arm and two-period crossover Phase I study. Subjects were randomized evenly to a single dose of LZM003 or reference drug injected subcutaneously, with a 10-day or longer between-treatment washout period. PK parameters, anti-drug antibodies (ADAs), and adverse events (AEs) were assessed. The primary PK endpoints were area under the curve (AUC) of the concentration-time curve from zero to last quantifiable concentration (AUC0-t), AUC from zero to infinity (AUC0-∞), and peak concentration (Cmax). Bioequivalence was determined by assessing whether the 90% confidence intervals (CIs) for the geometric mean ratio (GMR) of LZM003 to reference drug fell within predefined margins of 80% -125%. RESULTS: Forty-eight subjects (24 males and 24 females) were enrolled and one subject withdrew for personal reasons. Mean values of primary PK parameters were similar (p > 0.05) between LZM003 and the reference drug. The 90% CIs for primary PK endpoints' GMR of LZM003 to reference drug ranged between 0.9144 and 1.1845, which were within bioequivalence margins of 80-125%. Incidence of AEs was similar (p > 0.05) between the two groups. Neither LZM003 nor reference drug produced anti-drug antibody (ADA) in healthy subjects. CONCLUSION: LZM003 and reference drug were bioequivalent. The PK and safety assessments were similar (p > 0.05) between the two formulations in healthy Chinese subjects. TRIAL REGISTRATION NUMBER: ChiCTR-IIR-16010158 (http://www.chictr.org.cn). TRIAL REGISTRATION DATE: December 15, 2016.

Open labeled, uncontrolled pharmacokinetic study of a single intramuscular hCG dose in healthy male volunteers.

The current study was designed to compare blood and cerebrospinal fluid (CSF) pharmacokinetic characteristics of two forms of human chorionic gonadotropin (hCG): Pregnyl(R), derived from human urine, and Ovitrelle(R) a recombinant form. Two separate groups, each with six older male human subjects, were dosed with either form of the drug at 10,000 IU intramuscularly (IM), and followed over a 36-hour period. No significant difference in the serum level of hCG was observed for either preparation of hCG (Peak serum conc.: 316 +/- 53 vs. 270 +/- 60 at 12 hours, 311 +/- 38 vs. 321 +/- 60 IU/l at 24 hours; AUC: 10,053 +/- 1,268 vs. 8,793 +/- 1,768, Pregnyl and Ovitrelle, mean +/- SD, respectively). Additionally, both forms of circulating hCG distributed to the central nervous system (CNS) as manifest by an increased number of subjects whose CSF samples showed detectable levels of hCG in their CSF over a 36-hour period. Similarly, there was no significant difference between the two forms when distribution to the CSF was compared at 36 hours (2.0 and 1.2 IU/l; range 1.9 - 2.1 and 1 - 1.4 IU/l for Pregnyl and Ovitrelle, resp.). This preliminary study in normal human volunteers suggests that the two forms of hCG tested, Ovitrelle(R) and Pregnyl(R), when administered IM, distribute in a similar fashion into the circulation and CSF. Consequently, we conclude that these two drugs demonstrate no statistical significant difference with respect to the CSF.

Choice of protocol for the in vivo bioassay of equine Chorionic Gonadotropin (eCG / PMSG) in immature female rats.

Equine Chorionic Gonadotropin (eCG) previously known as Pregnant Mare Serum Gonadotropin (PMSG) has been used for decades in regulating reproduction in various domestic animal species. Its use necessitates a good measurement of its bioactivity in commercial preparations. The EUROPEAN PHARMACOPEIA (EP 7.0) recommends 5-6 subcutaneous injections in immature female rats for the in vivo bioassay for eCG as in the case for measurement of FSH bioactivity in the Steelman & Pohley assay (1953). This recommendation is in marked contrast with the classical and long-time used PMSG assay of Cole & Erway (1941) that includes only one subcutaneous injection, 3 days before measurement of ovarian weight. As this difference introduces much confusion in the determination of eCG/PMSG bioactivity in commercial sources, we have performed parallel assays of several PMSG preparations, with both protocols. The single-injection protocol takes into account the long half-life of eCG in bloodstream and provokes an ovarian stimulation at lower concentrations than the multiple-injection protocol. As the single-injection protocol also mimicks the protocol used in cattle, it is preferable to the multiple-injection protocol of the current EP.

A constitutively active mutant of the human lutropin receptor (hLHR-L457R) escapes lysosomal targeting and degradation.

Using biochemical and imaging approaches, we examined the postendocytotic fate of the complex formed by human choriogonadotropin (hCG) and a constitutively active mutant of the human lutropin receptor (hLHR-L457R) found in a boy with precocious puberty and Leydig cell hyperplasia. After internalization, some of the complex formed by the hLHR-wild type (hLHR-wt) and hCG recycles to the cell surface, and some is found in lysosomes where the hormone is degraded. In contrast, the complex formed by the hLHR-L457R and hCG is not routed to the lysosomes, most of it is recycled to the cell surface and hormone degradation is barely detectable. For both, hLHR-wt and -L457R, there is an hCG-induced loss of cell surface receptors that accompanies internalization but this loss cannot be prevented by leupeptin. The removal of recycling motifs of the hLHR by truncation of the C-terminal tail at residue 682 greatly enhances the lysosomal accumulation of the hormone-receptor complexes formed by the hLHR-wt or the L457R mutant, the degradation of the internalized hormone, and the loss of cell surface receptors. The degradation of the hormone internalized by these mutants as well as the loss of cell surface receptors is largely prevented by leupeptin. These results highlight a previously unrecognized complexity in the postendocytotic trafficking of the hLHR and document a clear difference between the properties of the constitutively active mutant and the agonist-activated hLHR-wt. This lack of lysosomal degradation of the L457R mutant could contribute to its constitutive activity by prolonging the duration of signaling.

Relationship between serum human chorionic gonadotrophin levels and body mass index in women undergoing in vitro fertilisation cycles.

OBJECTIVE: To ascertain if serum concentrations following injection of human chorionic gonadotropin (hCG) influenced the outcome of in vitro fertilisation (IVF) treatment and correlated to body mass index (BMI). STUDY DESIGN: A prospective study conducted with the participation of 149 women undergoing IVF and/or intracytoplasmic sperm injection (ICSI) treatment at the regional IVF Unit in Liverpool, UK. The BMI of each individual was calculated and serum hCG concentrations were measured at 12 and 36 h following a subcutaneously (SC) injection of 5000 IU hCG. The main outcome measures were fertilisation rate and biochemical pregnancy rate. RESULTS: No correlation was found between serum hCG levels at 12 and 36 h with the number of oocytes retrieved or the number of oocytes fertilised. Furthermore, there was no correlation between BMI and hCG levels at 12 and 36 h following administration (Pearson's correlation coefficient: -0.23, -0.24, respectively). CONCLUSION: Our results suggest that the serum concentrations of hCG do not influence IVF outcome and that the serum levels of hCG achieved following administration do not correlate with the individual's BMI. Serum hCG concentration also does not correlate with number of oocytes collected or fertilisation rate.

Effect of protease inhibitors on pulmonary bioavailability of therapeutic proteins and peptides in the rat.

The objective of the present study was to evaluate the effect of protease inhibitors on the pulmonary absorption of therapeutic peptides and proteins with varying molecular weights. Dry powder formulations of leuprolide (1.2 kD), salmon calcitonin (3.4 kD), human insulin (5.8 kD), human leptin (16.0 kD), and human chorionic gonadotropin (HCG) (36.5 kD) were prepared with or without protease inhibitors; aprotinin and bestatin. The formulations were administered intrapulmonary to anesthetized rats. The pharmacokinetics of these proteins were assessed by measuring serum drug concentrations. In addition, in vitro stability of these proteins in rat lung homogenate was assessed using the trifluoroacetic acid method. Bioavailability of leuprolide following pulmonary administration was 75% higher compared to subcutaneously administered leuprolide. Protease inhibitors had little or no effect on the pulmonary bioavailability of leuprolide. However, protease inhibitors (1 mg/kg) increased the bioavailability of calcitonin by more than 50%. Similarly, the bioavailabilities of leptin and HCG in the presence of bestatin were increased by 1.9 and 2.1-fold, respectively. Leuprolide was stable both in the lung cytosol and subcellular pellets with about 10% degradation at the end of the study period (4h). In contrast, calcitonin, insulin, leptin and HCG were significantly degraded in the lung cytosol and subcellular pellets. Presence of protease inhibitors in formulation could improve the stability of protein drugs. The results of this study demonstrate that the pulmonary absorption of proteins may be enhanced by the selection of optimal concentration and type of protease inhibitor.

Similarity of the clearance rates of free alpha-subunit and alpha-subunit dissociated from intact human chorionic gonadotropin, despite differences in sialic acid contents.

It is well known that the MCR of proteins can be influenced by their carbohydrate structure; i.e. the presence of terminal galactose on proteins results in uptake by hepatic receptors for galactose-terminated glycoproteins. Thus, a protein with its galactose residues covered or removed exhibits a far longer half life in plasma than one with its galactose residues exposed. The free alpha-subunit of human CG (hCG) has been shown to have a different carbohydrate composition than does the alpha-subunit dissociated from the intact hormone. In our laboratory, analysis of alpha-subunits isolated from pregnancy urine indicated that the alpha-subunit dissociated from hCG (hCG alpha) contains primarily monosialylated oligosaccharides, whereas the free alpha-subunit contains more than one sialic acid per oligosaccharide. This difference in the degree of sialylation prompted us to examine the clearance rates of these two subunits. Accordingly, free alpha and hCG alpha were purified by affinity chromatography and labeled with 125I. The labeled subunits were injected iv into rats and serum samples were removed at various time intervals over a 2-h period. The amount of [125I]alpha-subunit remaining in the serum was determined by immunoprecipitation using an antiserum to hCG alpha. The disappearance curves for the two subunits were indistinguishable and could be analyzed by a biexponential model. The t 1/2 of the faster component was 5 min, while the t 1/2 of the slower component was 74 min. In order to determine whether or not terminal galactose was present on either the hCG alpha or the free alpha-subunit, the labeled molecules were subjected to lectin column chromatography using Ricin or peanut lectin linked to agarose. Both of these lectins bind galactose but have different specificities with respect to the penultimate sugar. Both subunit preparations contained only minor amounts of material which could bind or either lectin. However, after desialylation, both hCG alpha and free alpha bound extensively to Ricin, indicating the presence of penultimate galactose residues in both. We conclude that terminal galactose residues are not present on the oligosaccharides of either hCG alpha or free alpha-subunits, and that the difference observed in the sialic acid contents of the two subunits does not affect their rates of clearance.

Epidermal growth factor inhibits follicular response to human chorionic gonadotropin: possible role of cell to cell communication in the response to gonadotropin.

Epidermal growth factor (EGF) affects follicular steroidogenesis and expression of gonadotropin receptors. The effects of EGF on hCG-induced estradiol and progesterone secretion and ovulation were examined in the in vitro perfused rabbit ovary. We also examined the effects of EGF on hCG-induced progesterone secretion by isolated granulosa cells. In addition, distribution of hCG within the follicle was probed by immunohistochemical means 30 min after its administration to the in vitro perfused ovary. EGF significantly (P less than 0.05) reduced hCG-induced secretion of estradiol (control, 117 +/- 12 pg/min.follicle; 10 ng/ml EGF, 55 +/- 10) and progesterone (control, 18.2 +/- 1.2 ng/min.follicle; 10 ng/ml EGF, 11.9 +/- 0.8) by the perfused ovary. In contrast, EGF did not inhibit hCG-induced progesterone secretion by isolated granulosa cells. Ovulatory efficiency (number of ovulated ova per number of mature follicles x 100) when EGF was given 30 min before hCG was reduced dose-dependently from 58.2% with no EGF to 8.3% with 10 ng/ml EGF (P less than 0.001). Ovulation was not inhibited by EGF when it was given 30 min after hCG. Distribution of hCG in the preovulatory follicle was confined to the basement membrane, thecal cell layer, and a small fraction of the outer granulosa cell layer. These observations suggest that gonadotropin stimulates the follicle through the release of a secondary signal(s) from ligand-bound granulosa cells near the follicle wall to unexposed cells of the inner avascular area. EGF may inhibit the follicular response to hCG by attenuation of this cell to cell communication.

Stimulation of testosterone production in the cynomolgus monkey in vivo by deglycosylated and desialylated human choriogonadotropin.

Modifications of carbohydrate structures of hCG, such as deglycosylation or desialylation, have been shown to reduce the biological activity of the hormone derivatives in vivo. We posed the question of whether deglycosylated hCG (dg-hCG) and desialylated hCG (ds-hCG) would behave as agonists at the LH/CG receptor in the primate in vivo, as this would bear on their potential clinical utility as LH/CG agonists or antagonists. Thus, we administered large doses (approximately 3 nmol) of highly purified dg-hCG, ds-hCG, hCG, or normal saline as a rapid iv injection to adult male cynomolgus monkeys (n = 3/group). Mean areas under the curves of plasma T over the first 6 h achieved with dg-hCG and ds-hCG were about 5-fold, significantly (P less than 0.05) greater than that in the saline controls and not significantly (P greater than 0.05) different from that in hCG-injected animals. Despite comparable plasma T responses in the first 6 h, mean plasma concentrations of ds-hCG, dg-hCG, and hCG differed dramatically among the groups. Plasma ds-hCG and dg-hCG levels were undetectable by 15 and 180 min, respectively, while the mean plasma hCG level was more than 2.10 nmol/L at 360 min. These data indicate that 1) dg-hCG is a full agonist at the LH/CG receptor in the primate in vivo, despite having minimal intrinsic activity in the rat Leydig cell adenyl cyclase assay and being able to near-completely antagonize hCG action therein; and 2) ds-hCG is a full agonist in the monkey in vivo, capable of stimulating a full testicular response over 6 h, despite being cleared from the circulation in 15 min. We conclude that the signal transduction system at the monkey LH/CG receptor is capable of achieving full steroidogenesis despite dramatically shortened exposure to stimulus or exposure to a stimulus with markedly reduced adenyl cyclase-stimulating activity in vitro.

Changes in peripheral progestagen levels in early pregnant gilts following injection of human chorionic gonadotrophin.

The capacity of human chorionic gonadotrophin (hCG) to raise plasma progestagen levels during the first 8 days of gestation in gilts was examined. The effective half-times of hCG in gilts treated with 500 and 5000 i.u. hCG were 29.1 and 26.3 h respectively (P greater than 0.05). Neither 500 nor 5000 i.u. hCG caused rises in peripheral concentrations of progesterone or pregnenolone sulphate, and plasma pregnenolone concentrations declined (P less than 0.05) following hCG treatment. Apart from diminished total corpus luteal weights in gilts treated with 500 i.u. hCG (P less than 0.05) and lower peripheral progesterone levels in gilts treated with 5000 i.u. hCG (P less than 0.05), ovarian and plasma steroid characteristics of hCG-treated animals between 23 and 25 days of gestation were similar to control values. Furthermore, treatment with hCG did not affect embryo survival during the first 4 weeks of pregnancy, and plasma oestrone/oestrone sulphate levels provided no evidence for differences between control and treated animals in trophoblastic outgrowth. These results challenge the rationale for the treatment of early pregnant sows with hCG in order to reduce the levels of embryonic wastage in early pregnancy.

hCGbeta core fragment is a metabolite of hCG: evidence from infusion of recombinant hCG.

The availability of recombinant human chorionic gonadotrophin (r-hCG) has allowed us to measure its metabolic and renal clearance rates and to study the origin of the beta core fragment of hCG (hCGbetacf). Serum and urine samples were collected from six subjects, after an intravenous injection of 2 mg (equivalent to 44 000 IU Urinary hCG) r-hCG, and assayed for hCG and the beta subunit (hCGbeta). Urine from four of the subjects was also subjected to gel chromatography and assayed for hCGbetacf and hCG. r-hCG, administered as an intravenous dose, was distributed, initially in a volume of 3.4+/-0.7 l (mean+/-s.d.) and then in 6.5+/-1.15 l at steady-state. The disappearance of r-hCG from serum was bi-exponential, with an initial half-life of 4.5+/-0.7 h and a terminal half-life of 29.0+/-4.6 h. The mean residence time was 28. 6+/- 3.6 h and the total systemic clearance rate of r-hCG was 226+/-18 ml/h. The renal clearance rate was 28.75+/-6.2 ml/h (mean+/-s.d). hCGbetacf was detected in all urine samples collected at 6 h intervals. Over the 138 h period of urine collection, 12.9% (range 10.1-17.3% ) of r-hCG injected was recovered as the intact molecule and 1.7% (range 0.8-2.9%) was recovered as the hCGbetacf, in 4 subjects. The molar ratio of hCGbetacf to hCG in urine increased from 3.1+/-1.7%, on day 1, to 76+/-34.3% (mean+/-s.e.m.) on day 5, after r-hCG infusion, suggesting that hCGbetacf is a metabolic product of the infused r-hCG.

Two-sided culture of human placental trophoblast. Morphology, immunocytochemistry and permeability properties.

We describe the culture of human term placental trophoblast cells on cell-free amniotic membrane, with medium on both sides. Over the course of 2 days, the isolated cells, initially simple, mononucleated and probably cytotrophoblast, form a confluent layer of multinucleated syncytial cells with morphological and immunocytochemical properties of syncytiotrophoblast. This layer becomes polarized with respect to morphology, alkaline phosphatase distribution and hCG secretion. Contamination with amnion cells, and with other cell types that are present in placental tissue, was less than 1 per cent. A preliminary investigation of the permeability properties of the preparation showed that the trophoblast cell layer, rather than the amniotic membrane, was rate-limiting to transtrophoblast transfer, but that possible effects of the supporting membrane should be considered. The transtrophoblast transfer of D-glucose and the non-metabolisable analogue, 3-O-methyl-D-glucose (3OMG), had saturable and non-saturable/leak components in both directions, indicating that carrier-mediated processes were involved. The non-metabolisable amino acid 2-aminoisobutyrate (AIB) was both accumulated within the trophoblast cells, and transferred by saturable and non-saturable processes from the microvillous side, but no saturable accumulation or transfer was observed from the basal side, at the concentrations tried. The results suggest that this model may prove suitable for studies of transtrophoblast transfer.

Fast renal trapping of porcine luteinizing hormone (pLH) shown by 123I-scintigraphic imaging in rats explains its short circulatory half-life.

BACKGROUND: Sugar moieties of gonadotropins play no primary role in receptor binding but they strongly affect their circulatory half-life and consequently their in vivo biopotencies. In order to relate more precisely hepatic trapping of these glycoproteic hormones with their circulatory half-life, we undertook a comparative study of the distribution and elimination of porcine LH (pLH) and equine CG (eCG) which exhibit respectively a short and a long half-life. This was done first by following half-lives of pLH in piglets with hepatic portal circulation shunted or not. It was expected that such a shunt would enhance the short half-life of pLH. Subsequently, scintigraphic imaging of both 123I-pLH and 123I-eCG was performed in intact rats to compare their routes and rates of distribution and elimination. METHODS: Native pLH or eCG was injected to normal piglets and pLH was tested in liver-shunted anaesthetized piglet. Blood samples were recovered sequentially over one hour time and the hormone concentrations were determined by a specific ELISA method. Scintigraphic imaging of 123I-pLH and 123I-eCG was performed in rats using a OPTI-CGR gamma camera. RESULTS: In liver-shunted piglets, the half-life of pLH was found to be as short as in intact piglets (5 min). In the rat, the half-life of pLH was also found to be very short (3-6 min) and 123I-pLH was found to accumulate in high quantity in less than 10 min post injection at the level of kidneys but not in the liver. 123I-eCG didn't accumulate in any organ in the rats during the first hour, plasma concentrations of this gonadotropin being still elevated (80%) at this time. CONCLUSION: In both the porcine and rat species, the liver is not responsible for the rapid elimination of pLH from the circulation compared to eCG. Our scintigraphic experiments suggest that the very short circulatory half-life of LH is due to rapid renal trapping.

Disappearance of exogenously administered human chorionic gonadotropin.

Concentrations of human chorionic gonadotropin (hCG) were measured after intramuscular hCG administration in 34 patients undergoing ovarian stimulation in an in vitro fertilization program. Serum hCG levels were detectable by an immunoenzymetric assay up to 14 days after injection. Individual variation in hCG concentration after injection could be minimized by expressing the daily hCG level as a fractional distribution of the value observed 36 hours after hCG administration (hCG0). In nonpregnant patients, less than 10% of the hCG0 value was found on day 10. The disappearance rate measured 36 hours after injection of hCG was exponential with a mean half-life of 2.32 days. These findings are significant for ovarian stimulation protocols, including exogenous hCG, with respect to timing and accuracy of quantitative pregnancy testing.

Slow excretion of exogenous human chorionic gonadotropin simulating repeated pregnancies and pregnancy losses.

We report a patient undergoing hMG-induced superovulation who demonstrated delayed excretion of hCG, originally believed to be because of successive biochemical pregnancies. However, sequential hCG titers after administration of exogenous hCG demonstrated a longer than normal half-life for the excretion of hCG in this patient. To what extent delayed excretion of hCG contributes to the diagnosis of biochemical pregnancy in assisted reproductive technology programs has yet to be determined.