Development and clinical experience with the new evidence-based tocolytic atosiban

No impairment of contextual fear memory consolidation by oxytocin receptor antagonism in male rats

Oxytocin is a peptide released into brain regions associated with the processing of aversive memory and threat responses. Given the expression of oxytocin receptors across this vigilance surveillance system of the brain, we investigated whether pharmacological antagonism of the receptor would impact contextual aversive conditioning and memory. Adult male rats were conditioned to form an aversive contextual memory. The effects of peripheral administration of either the competitive antagonist Atosiban or noncompetitive antagonist L-368,899 were compared to saline controls. Oxytocin receptor antagonism treatment did not significantly impact the consolidation of aversive contextual memory in any of the groups. We conclude that peripheral antagonism of oxytocin signalling did not impact the formation of aversive memory.

New medicines for spontaneous preterm birth prevention and preterm labour management: landscape analysis of the medicine development pipeline

BACKGROUND

There are few medicines in clinical use for managing preterm labor or preventing spontaneous preterm birth from occurring. We previously developed two target product profiles (TPPs) for medicines to prevent spontaneous preterm birth and manage preterm labor. The objectives of this study were to 1) analyse the research and development pipeline of medicines for preterm birth and 2) compare these medicines to target product profiles for spontaneous preterm birth to identify the most promising candidates.

METHODS

Adis Insight, Pharmaprojects, WHO international clinical trials registry platform (ICTRP), PubMed and grant databases were searched to identify candidate medicines (including drugs, dietary supplements and biologics) and populate the Accelerating Innovations for Mothers (AIM) database. This database was screened for all candidates that have been investigated for preterm birth. Candidates in clinical development were ranked against criteria from TPPs, and classified as high, medium or low potential. Preclinical candidates were categorised by product type, archetype and medicine subclass.

RESULTS

The AIM database identified 178 candidates. Of the 71 candidates in clinical development, ten were deemed high potential (Prevention: Omega-3 fatty acid, aspirin, vaginal progesterone, oral progesterone, L-arginine, and selenium; Treatment: nicorandil, isosorbide dinitrate, nicardipine and celecoxib) and seven were medium potential (Prevention: pravastatin and lactoferrin; Treatment: glyceryl trinitrate, retosiban, relcovaptan, human chorionic gonadotropin and Bryophyllum pinnatum extract). 107 candidates were in preclinical development.

CONCLUSIONS

This analysis provides a drug-agnostic approach to assessing the potential of candidate medicines for spontaneous preterm birth. Research should be prioritised for high-potential candidates that are most likely to meet the real world needs of women, babies, and health care professionals.

Randomized trial of oxytocin antagonist atosiban versus beta-adrenergic agonists in the treatment of spontaneous preterm labor in Taiwanese women

BACKGROUND/PURPOSE

Management of preterm labor involves the use of tocolytic drugs to inhibit preterm uterine contractions. This study compared the efficacy and safety of intravenous administration of atosiban and ritodrine in the treatment of spontaneous preterm labor.

METHODS

A randomized study was conducted in pregnant women of Chinese origin in Taiwan with threatened preterm delivery. Patients were randomized to receive either atosiban (n = 23) or ritodrine (n = 22). Tocolytic efficacy of the drug was assessed as the proportion of women who did not deliver and did not need alternative tocolytic treatment at 7 days after therapy initiation. Safety of the drugs was assessed as the number of adverse events or neonatal morbidity.

RESULTS

The number of women who did not deliver and did not require alternative tocolytic therapy at 7 days was similar between the atosiban and ritodrine groups. There were no serious adverse events, but maternal cardiovascular adverse events, particularly tachycardia, occurred significantly more in women treated with ritodrine (0% atosiban vs. 18.18% ritodrine, p < 0.05). There was no difference in neonatal or infant outcome between the two drugs.

CONCLUSION

The present study showed similar effectiveness between atosiban and ritodrine, while tachycardia occurred more frequently in women treated with ritodrine. These results indicate that atosiban is an effective tocolytic drug without the conventional cardiovascular side effects often seen with beta-agonist treatment.

Consequences of early experiences and exposure to oxytocin and vasopressin are sexually dimorphic

In the socially monogamous prairie vole, we have observed that small changes in early handling, as well as early hormonal manipulations can have long-lasting and sexually dimorphic effects on behavior. These changes may be mediated in part by changes in parental interactions with their young, acting on systems that rely on oxytocin (OT) and arginine vasopressin (AVP). Knowledge of both endogenous and exogenous influences on systems that rely on OT and AVP may be helpful in understanding sexually dimorphic developmental disorders, such as autism, that are characterized by increased anxiety and deficits in social behavior.

Oxytocin has dose-dependent developmental effects on pair-bonding and alloparental care in female prairie voles

The present study examines the developmental consequences of neonatal exposure to oxytocin on adult social behaviors in female prairie voles (Microtus ochrogaster). Female neonates were injected within 24 h of birth with isotonic saline or one of four dosages of oxytocin (OT). As adults, females were tested in an elevated plus-maze paradigm (a measure of anxiety and exploratory behavior), and for alloparental behavior and partner preferences. At 2 mg/kg OT, females took longer to approach pups, but were the only group to form a statistically significant within-group partner preference. At 4 mg/kg OT, females retrieved pups significantly more frequently but no longer displayed a partner preference; while females treated developmentally with 8 mg/kg spent significantly more time in side-to-side contact with a male stranger than any other treatment group. OT may have broad developmental consequences, but these effects are not linear and may both increase and decrease the propensity to display behaviors such as pair-bonding.

Feto-placental communication system with the myometrium inpregnancy and parturition: the role of hormones, neurohormones, inflammatory mediators, and locally active factors

Pregnancy is a unique condition in which the conceptus is allowed to implant, survive, develop, and reach a considerable organ growth and maturation within the maternal body despite the fact that it is half genetically different from the mother. Moreover, it deeply influences the overall endocrine, metabolic, and immunological functions of the recipient mother. These objectives are accomplished through the establishment of several communication systems in which a large array of substances produced by the feto-placental unit reach specific maternal target organs and/or systems and modulate their function. The myometrium is a fundamental reproductive tissue involved in pregnancy maintenance as well as in labor onset and progression and is a potential target organ for such a communication system. An appropriate regulation of myometrial function is a key condition required for pregnancy to develop physiologically until full term is reached and for labor to start. Emerging experimental and clinical evidence suggests that a very complex feto-placental biomolecular communication system exists with the myometrium and is actively operative in the control of myometrial contractility in pregnancy and parturition through the production of a continuously increasing number of substances with endocrine, paracrine, and immunoregulatory actions.

Neonatal manipulation of oxytocin affects expression of estrogen receptor alpha

In adult females many of the effects of the neuropeptide oxytocin are steroid, and especially estrogen dependent. Here we demonstrate for the first time that neonatal manipulation of oxytocin can affect the expression of estrogen receptor alpha. On the first day of postnatal life male and female prairie voles (Microtus ochrogaster) were randomly assigned to receive one of four treatments; (a) 50 microl i.p. injection of 3 microg oxytocin (approximately 1 microg/g), (b) 0.3 microg of an oxytocin antagonist (approximately 0.1 microg/g), or (c) isotonic saline. A fourth group was handled, but not injected. On postnatal day 8 or 21, brain tissue was collected, fixed and sectioned. Free-floating sections were stained for estrogen receptor alpha using immunocytochemistry, and estrogen receptor alpha immunoreactive neurons were compared by age, treatment, and sex. To compare the temporal expression of estrogen receptor alpha an additional set of brains was collected from untreated males and females on the day of birth. The effects of oxytocin manipulations were age dependent, sexually dimorphic, and site-specific. While there were no significant treatment effects on postnatal day 8, by postnatal day 21 females that received oxytocin showed a significant increase in the number of cells expressing estrogen receptor alpha-immunoreactivity in the ventromedial nucleus of the hypothalamus. Treatment with oxytocin antagonist resulted in a significant decrease in estrogen receptor alpha-immunoreactivity in the medial preoptic area in postnatal day 21 females. While there were no significant effects in males, males treated with oxytocin antagonist trended toward a reduction in estrogen receptor alpha-immunoreactivity in the medial amygdala. The results indicate that oxytocin can have organizational effects on the expression of estrogen receptor alpha, that these effects are sexually dimorphic, and finally that during the preweaning period the development of estrogen receptor alpha is sexually dimorphic.

Oxytocin inhibits T-type calcium current of human decidual stromal cells

CONTEXT

Little is known about the crosstalk between the decidua and myometrium in relation to human labor. The hormone oxytocin (OT) is considered to be a key mediator of uterine contractility during parturition, exerting some of its effects through calcium channels.

OBJECTIVE

The objective was to characterize the effect of OT on the T-type calcium channel in human decidual stromal cells before and after the onset of labor.

DESIGN

The nystatin-perforated patch-clamp technique was used to record inward T-type calcium current (I(Ca(T))) from acutely dispersed decidual stromal cells obtained from women at either elective cesarean section [CS (nonlabor)] or after normal spontaneous vaginal delivery [SVD (labor)].

SETTING

These studies took place at the University of Nottingham Medical School.

RESULTS

I(Ca(T)) of both SVD and CS cells were blocked by nickel (IC(50) of 5.6 microm) and cobalt chloride (1 mm) but unaffected by nifedipine (10 microm). OT (1 nm to 3.5 microm) inhibited I(Ca(T)) of SVD cells in a concentration-dependent manner, with a maximal inhibition of 79.0% compared with 26.2% in decidual cells of the CS group. OT-evoked reduction of I(Ca(T)) was prevented by preincubation with the OT antagonist L371,257 in the SVD but not CS group. OT, in a concentration-dependent manner, displaced the steady-state inactivation curve for I(Ca(T)) to the left in the SVD group with no significant effect on curves of the CS group.

CONCLUSION

Inhibition of I(Ca(T)) by OT in decidual cells obtained during labor may signify important functional remodeling of uterine signaling during this period.

Evaluación farmacoeconómica de dos protocolos de tocolisis para la inhibición del parto prematuro

OBJECTIVE

Pharmacoeconomic assessment of two tocolysis protocols alternatively using atosiban or ritodrine as first-choice tocolytic agent able to delay birth for 48 hours in the acute management of premature birth risk in gravid women.

METHODS

The modeling technique used for the selection of the most efficient protocol was the decision analysis. A search for controlled clinical trials comparing the effectiveness and/or safety of atosiban versus ritodrine was performed in Medline and the Cochrane Library. Only differential costs were considered for cost analysis.

RESULTS

Cost-effectiveness obtained with the protocol including ritodrine as first-choice drug was Euros 194/effectiveness unit, and Euros 632/effectiveness unit when atosiban is used. The sensitivity analysis shows sensitivity only for an incidence of acute lung edema greater than 8% or a cost of at least Euros 50,000.

CONCLUSION

A tocolysis protocol using ritodrine as first-choice agent and atosiban as rescue drug is the most efficient option based on available evidence. In pregnant women where the likelihood of developing acute pulmonary edema is high, or when therapy cost is high, atosiban may be an appropriate alternative option.

Sex differences and developmental effects of manipulations of oxytocin on alloparenting and anxiety in prairie voles

In adult animals, peptide hormones, including oxytocin and arginine vasopressin, have been implicated in both parental behavior and the modulation of anxiety. The purpose of this study was to examine the consequences of developmental manipulations of oxytocin for the later expression of alloparental behavior as well as behavioral responses to a novel environment, the elevated plus maze (EPM). Prairie voles (Microtus ochrogaster), a cooperatively breeding species, were selected for this study. On neonatal Day 1, pups received an ip injection of oxytocin or oxytocin antagonist, or were controls, receiving either saline or handling only. At 21 and approximately 60 days of age, each animal was tested for parental care toward novel stimulus pups. At approximately 67 days, an EPM test was administered. Control females at 60 days of age were more likely to attack pups and spent less time in the open arm of the EPM, both of which might reflect higher levels of anxiety in females than males. In males, neonatal treatment with oxytocin antagonist was associated with reductions in parental care, especially during the initial exposure to pups on Day 21. Female behavior was not significantly changed as a function of neonatal treatments. Findings to date implicate vasopressin in the behavioral changes in males, that in later life followed a single exposure to an oxytocin antagonist, and suggest caution in the clinical use of agents such as Atosiban, which may have the potential to influence infant development.

Design of potent and selective agonists for the human vasopressin V1b receptor based on modifications of [deamino-cys1]arginine vasopressin at position 4

The glutamine(4) residue in [deamino-Cys(1)]arginine vasopressin (dAVP) was replaced by a broad series of aliphatic, aromatic, polar, and charged amino acids to give the following peptides: d[Gly(4)]AVP (1), d[Ala(4)]AVP (2), d[Abu(4)]AVP (3), d[Nva(4)]AVP (4), d[Nle(4)]AVP (5), d[Leu(4)]AVP (6), d[Ile(4)]AVP (7), d[Thi(4)]AVP (8), d[Phe(4)]AVP (9), d[Tyr(4)]AVP (10), d[Trp(4)]AVP (11), d[Asn(4)]AVP (12), d[Ser(4)]AVP (13), d[Thr(4)]AVP (14), d[Dap(4)]AVP (15), d[Dab(4)]AVP (16), d[Orn(4)]AVP (17), d[Lys(4)]AVP (18), d[Arg(4)]AVP (19), d[Har(4)]AVP (20), and d[Glu(4)]AVP (21). All peptides were synthesized by solid-phase methods using BOC chemistry for all but one peptide (8), which required the use of Fmoc chemistry. The binding and functional properties of these position 4 substituted analogues of dAVP (d[X(4)]AVP) and the previously reported d[Cha(4)]AVP (Derick et al. Endocrinology 2002, 143, 4655-4664) were evaluated on human arginine vasopressin (AVP) V(1a), V(1b), and V(2) receptors and on the human oxytocin (OT) receptor expressed in living Chinese hamster ovary (CHO) cells. Binding studies revealed that broad modifications of the fourth residue of dAVP do not significantly alter affinity for the human V(1b) receptor. Only aromatic (Phe, Tyr, Trp) or negatively charged (Glu) residues reduce V(1b) affinity. By contrast, the human V(1a) and more particularly the human V(2) and the OT receptors are more sensitive to many of these modifications. Thus, the replacement of the Gln(4) residue of dAVP by aliphatic (Leu, Cha) or positively charged (Orn, Lys, Arg, Har) amino acids led to analogues exhibiting drastic reductions of their affinity for the human V(1a), V(2), and OT receptors. Consequently, in addition to the previously reported d[Cha(4)]AVP, peptides 6 and 17-20 display excellent selectivities for the human V(1b) receptor. The key structural requirement responsible for optimal V(1b) selectivity appears to be the length and branching of the aliphatic side chain of the fourth residue of dAVP. Functional studies performed on CHO cells expressing the different human AVP/OT receptors confirm the V(1b) selectivity of peptides 6, 17, 18, 20, and d[Cha(4)]AVP. However, d[Arg(4)]AVP (19), which triggers an excellent coupling between the human V(2) receptor and adenylyl cyclase, was found to exhibit both V(1b) and V(2) agonism in functional tests. More interestingly, these functional experiments revealed that, depending on the AVP/OT receptor, a given d[X(4)]AVP analogue may behave as a full agonist or as a partial agonist. This strongly suggests that the fourth residue of dAVP plays an important role in the coupling between the hormone-receptor complex, the heterotrimeric G protein, and the effectors. In conclusion, the synthesis of these d[X(4)]AVP analogues led to the discovery of new V(1b) agonists with high affinity and greatly enhanced selectivities. Thus, in addition to d[Cha(4)]AVP, d[Leu(4)]AVP (6), d[Orn(4)]AVP (17), d[Lys(4)]AVP (18), and d[Har(4)]AVP (20) are useful new tools for studying the structure and the function of the human V(1b) receptor.

Évaluation de l'algorithme de prise en charge des appels pour menace d'accouchement prématuré utilisé par la cellule de transfert périnatal de la région Rhône-Alpes

OBJECTIVE

Preterm labor is one of the major causes of concern for level I and II obstetricians. The purpose of this study was to determine the incidence of in utero transfer performed for preterm labor. We also aimed to evaluate the algorithm we used in case of call for preterm labor. This algorithm allowed us to study the rate of endovaginal sonography use prior to in utero transfer, to calculate its predictive value and to evaluate the risk of delivery during transfer.

PATIENTS AND METHOD

We conducted an 8-months prospective study of all calls for preterm labor received at a regional call center in France (EU). All obstetrical data were entered in a computerized anonymous database. Three months after the first call midwives collected data from the receiving hospital.

RESULTS

Calls for preterm labor account for 40% of calls for in utero transfer. Two hundred and sixty-five calls have been received for preterm labor; among them 50 cases were associated with a preterm rupture of membrane, a maternal or fetal pathology and 14 cases were lost for follow-up. Those 64 cases were excluded leaving 201 cases for analysis. Twenty-eight had a cervix dilated 4 cm, or more, while 173 had a cervix dilated less than 4 cm. Fifty percent of woman that had a cervical dilatation of 4 cm or more delivered more than 4 h after the call. Among the 173 patients that had a cervix dilated less than 4 cm, 71% had not delivered 7 days after the hotline call and 26% had an endovaginal ultrasonography performed before the transfer. None of the women that had a cervical length longer than 27 mm delivered in the 7 following days. None of the 176 women that were transferred delivered during the transfer.

DISCUSSION AND CONCLUSION

In utero transfer for preterm labor is the leading cause of in utero transfer. Endovaginal ultrasonography prior to transfer should be performed in order to avoid unnecessary transfer. Women who have a preterm labor with a cervical dilatation of 4 cm or more are not an absolute contra-indication to in utero transfer. In those cases the transfer indication should be discussed on a case-to-case basis including the actual term and the distance between hospitals.

Uterine contractility and directed sperm transport assessed by hysterosalpingoscintigraphy (HSSG) and intrauterine pressure (IUP) measurement

BACKGROUND

Uterine peristalsis sustains sperm transport and can be detected by hysterosalpingoscintigraphy (HSSG). This study is the first to be designed to investigate utero-tubal transport function by HSSG and uterine contractility by intrauterine pressure measurement (IUP) consecutively on the same day in the periovulatory phase.

METHODS

Twenty-one female subjects (mean age 28.4 years) without a gynecologic history were examined sequentially by HSSG and IUP on the same day to evaluate uterine contractility in relation to the utero-tubal transport function. In HSSG, intact transport function was visualized by the rapid uptake of 99m-technetium-marked albumin aggregates through the female genital tract. In IUP, the frequency of uterine contractions (UC/min), amplitude of uterine contractions and basal pressure tone were detected via a intrauterine catheter. HSSG and IUP were embedded in cycle monitoring with measurement of LH and estradiol.

RESULTS

In HSSG, a positive transport of inert particles was assessed in 20 of 21 subjects, in 76% to the side of the dominant follicle or on both sides of the oviduct, and in 19% a strict contralateral transport could be observed. In only one subject (5%), no transport was assessed. The mean value of uterine contractions was 3.4 UC/min (SD +/- 0.7), the mean amplitude was 12.0 mmHg (SD +/- 4.25 mmHg). Basal pressure tone was 70.7 mmHg. There was a statistically significant correlation with estradiol levels: none of the subjects with less than 3 UC/min showed an estradiol level higher than 100 pg/mL; nearly every patient (one exception) with more than 3 UC/min had an estradiol level higher than 100 pg/mL (p < 0.0001, Fisher's exact test).

CONCLUSIONS

Intact periovulatory utero-tubal transport function can be documented by HSSG and is caused by directed uterine contractility, measured consecutively by IUP. Uterine contractility is influenced by rising estradiol levels. Directed uterine contractility and intact utero-tubal transport function are considered necessary for intact sperm transport, mainly to the side bearing the dominant follicle to maximize fertility.

Developmental consequences of oxytocin

This paper examines the developmental effects of the mammalian neuropeptide, oxytocin (OT). In adults, OT is the most abundant neuropeptide in the hypothalamus and serves integrative functions, coordinating behavioral and physiological processes. For example, OT has been implicated in parturition, lactation, maternal behavior and pair bond formation. In addition, OT is capable of moderating behavioral responses to various stressors as well as the reactivity of the hypothalamic-pituitary-adrenal (HPA) axis. Neonates may be exposed to hormones of maternal origin, possibly including peptides administered to the mother in the perinatal period to hasten or delay birth and in milk; however, whether peptide hormones from the mother influence the developing infant remains to be determined. In rodents, endogenous OT is first synthesized during the early postnatal period, although its functions at this time are not well known. Experiments in neonatal prairie voles have documented the capacity of OT and OT receptor antagonists to have immediate and lifelong consequences for social behaviors, including adult pair bonding and parental behaviors, as well as the reactivity of the HPA axis; most of these effects are sexually dimorphic. Possible mechanisms for such effects, including long-lasting changes in OT and vasopressin, are summarized.

Recent evidence associated with the condition of preterm prelabour rupture of the membranes

PURPOSE OF REVIEW

The published literature on preterm prelabour rupture of the membranes is voluminous yet despite advances in obstetric and neonatal care, the problem remains a major cause of perinatal mortality and morbidity. The purpose of this review is to present recent evidence pertaining to the role of inflammatory mediators such as cytokines and the tissue damage and long-term handicap they cause, the molecular biology and physiology of membrane structure, the role of host susceptibility and the genetics of preterm birth and therapeutic options for the management of preterm prelabour rupture, including antibiotics, amnioinfusion and special situations.

RECENT FINDINGS

Neonatal morbidity from preterm prelabour rupture of the membranes is mainly related to oligohydramnios and pulmonary hypoplasia. Occupational factors have a significant effect on the occurrence and outcome following rupture. Matrix metalloproteinases control growth and remodelling of the pregnant uterus, placenta and membranes and are linked to a genetic predisposition to preterm birth through gene expression and variation. Transvaginal ultrasound scan, oncofetal fibronectin and the presence of abnormal genital tract flora (bacterial vaginosis) in pregnancy may help in the prediction of preterm birth.

SUMMARY

Preterm prelabour membrane rupture remains a management problem, particularly at very early gestations, yet obstetric and neonatal care can make a difference to outcome. While at early gestations the prognosis is poor, it is not hopeless. Careful selection of the recent literature on the subject might interest and inform those faced regularly with the problem, prevent therapeutic nihilism, promote confidence in our ability to make a difference and realise that we are not alone when faced with the therapeutic dilemma that is this condition.