Prostaglandin inhibitors as tocolytic agents

Actively Targeted Nanomedicines: A New Perspective for the Treatment of Pregnancy-Related Diseases

More than 20% of pregnant women experience serious complications during pregnancy, that gravely affect the safety of both the mother and the child. Due to the unique state of pregnancy, medication during pregnancy is subject to various restrictions. Nanotechnology is an emerging technology that has been the focus of extensive medical research, and great progress has recently been made in developing sensitive diagnostic modalities and efficient medical treatment. Accumulating evidence has shown that nanodrug delivery systems can significantly improve the targeting, reduce the toxicity and improve the bioavailability of drugs. Recently, some actively targeted nanomedicines have been explored in the treatment of pregnancy-related diseases. This article reviews common types of nanocarriers and active targeting ligands in common pregnancy-related diseases and complications such as preeclampsia, preterm birth, fetal growth restriction, and choriocarcinoma. Finally, the challenges and future prospects in the development of these nanomaterials are discussed, with the aim of providing guidance for future research directions.

Relationship of Notch Signal, Surfactant Protein A, and Indomethacin in Cervix During Preterm Birth: Mast Cell and Jagged-2 May Be Key in Understanding Infection-mediated Preterm Birth

Although it is thought that there is a close relationship between Notch signal and preterm birth, the functioning of this mechanism in the cervix is unknown. The efficacy of surfactants and prostaglandin inhibitors in preterm labor is also still unclear. In this study, 48 female CD-1 mice were distributed to pregnant control (PC), Sham, PBS, indomethacin (2 mg/kg; intraperitoneally), lipopolysaccharides (LPS) (25 μg/100 μl; intrauterine), LPS + IND, and Surfactant Protein A Block (SP-A Block: SP-A B; the anti-SP-A antibody was applied 20 µg/100μl; intrauterine) groups. Tissues were examined by immunohistochemistry, immunofluorescence, and Western blot analysis. LPS administration increased the expression of N1 Dll-1 and Jagged-2 (Jag-2). Although Toll-like receptor (Tlr)-2 significantly increased in the LPS-treated and SP-A-blocked groups, Tlr-4 significantly increased only in the LPS-exposed groups. It was observed that Jag-2 is specifically expressed by mast cells. Overall, this experimental model shows that some protein responses increase throughout the uterus, starting at a specific point on the cervix epithelium. Surfactant Protein A, which we observed to be significantly reduced by LPS, may be associated with the regulation of the epithelial response, especially during preterm delivery due to infection. On the contrary, prostaglandin inhibitors can be considered an option to delay infection-related preterm labor with their dose-dependent effects. Finally, the link between mast cells and Jag-2 could potentially be a control switch for preterm birth.

Liposomes: a nanoscale drug carrying system to prevent indomethacin passage to the fetus in a pregnant mouse model

OBJECTIVE

Indomethacin (IND) is a prostaglandin production inhibitor that reduces uterine contractions, but crosses the placenta leading to adverse fetal effects. Liposomes (LIP) are nanoscale systems clinically used to preferentially deliver a drug to the tissue of interest and simultaneously prevent distribution to unwanted locations. Our objective was to determine whether LIP could prevent the transfer of IND across the placenta to the fetus while preserving its pharmacological activity.

STUDY DESIGN

Multilamellar LIP were designed with a 150- to 200-nm size, fluorescently labeled, and loaded with IND. Timed pregnant CD1 mice (n = 6/group) on gestational day 18 were administered LIP, LIP-IND (1 mg IND/kg), or saline (SAL) via tail vein injection, or IND (1 mg/kg) via oral gavage. After 4 hours, the uterus, placenta, and fetuses were retrieved. LIP levels were visualized using fluorescent microscopy and quantitatively assessed by National Institutes of Health image processing software. LIP brightness values (mean ± SEM) in arbitrary units (AU) were normalized to the autofluorescence of the same tissue (as measured in SAL group). IND and prostaglandin E2 levels were assessed using liquid chromatography-tandem mass spectrometry and enzyme-linked immunosorbent assay, respectively.

RESULTS

The qualitative analysis of LIP distribution revealed that the system was primarily confined within the uterus, minimally detected within the placenta, and absent in the fetus. LIP fluorescence was greater in the uterus compared to placenta and fetus (uterus 15.3 ± 5.4 AU vs placenta 3.0 ± 3.5 AU vs fetus 4.4 ± 2.5 AU; P = .009). LIP-IND resulted in a 7.6-fold reduction in the IND levels in the fetus compared to IND alone (LIP-IND 10.7 ± 17.1 ng/g vs IND 81.3 ± 24.7 ng/g; P = .041). Prostaglandin E2 levels were significantly reduced in the uterus of animals given LIP-IND and IND compared to LIP and SAL.

CONCLUSION

LIP localized within the uterus and did not cross the placenta to the fetus. IND within the fetus was reduced 7.6-fold while encapsulated within the LIP and the pharmacologic effects of IND were maintained. Thus, LIP provide a novel therapeutic approach to correct the primary clinical limitation of IND by reducing placental passage to the fetus.

Effect of antenatal tocolysis on neonatal outcomes

OBJECTIVE

Detail adverse neonatal effects in pregnancies treated with indomethacin (I), magnesium sulfate (M) or nifedipine (N).

METHODS

Women in acute preterm labor with cervical dilatation 1-6 cm were randomized to receive one of three first-line tocolytic drugs.

RESULTS

There were 317 neonates (I = 103, M = 95, N = 119) whose mothers were treated with tocolytic therapy. There was no difference in gestational age at randomization (average 28.6 weeks' gestation) or at delivery (31.6 weeks' gestation, p = 0.551), birth weight (p = 0.871) or ventilator days (p = 0.089) between the three groups. Neonatal morbidity was not different between the three groups; respiratory distress syndrome (p = 0.086), patent ductus arteriosus (p = 0.592), sepsis (p = 0.590), necrotizing enterocolitis (p = 0.770), intraventricular hemorrhage (p = 0.669) and periventricular leukomalacia (p = 0.124).

CONCLUSIONS

There were no statistically significant differences between the three tocolytics as far as composite neonatal morbidity or mortality was concerned.

The adverse renal effects of prostaglandin-synthesis inhibition in the fetus and the newborn

OBJECTIVES

To summarize experimental animal data and to provide a limited literature review on the adverse renal effects of nonsteroidal anti-inflammatory drugs (NSAIDs) on the developing fetus and the maturing newborn.

DATA

The experimental data were obtained from anesthetized, ventilated, six- to eight-day-old rabbits that received an intravenous bolus of either acetylsalicylic acid (ASA), ibuprofen (IBU) or indomethacin (INDO). In one set of experiments, ASA was also tested in 12-week-old (young adult) rabbits. Renal function was monitored with inulin and para-aminohippuric acid clearances measuring glomerular filtration rate (GFR) and renal blood flow. The renal vascular resistance was calculated. All three nonspecific cyclo-oxygenase-1 or -2 (COX-1/2) inhibitors caused remarkably similar reversible, oliguric, acute renal failure (ARF). In young adult animals, the side effects were attenuated. The underlying pathophysiology is related to the carefully maintained low GFR of the fetus and the newborn, dependent on a delicate interplay between vasoconstriction (angiotensin II) and vasodilation (prostaglandins [PGs]). When PG-synthesis is inhibited, the vasoconstriction is relatively unopposed, causing ARF.

LITERATURE REVIEW

The renal effects of fetal exposure to NSAIDs are discussed, as are new insights into the role of COX-1/2 for a normal nephrogenesis. COX-nil or COX-inhibited animals have long lasting renal structural injury. Fetuses exposed in utero to significant amounts of NSAIDs have at birth various degrees of renal insufficiency and structural renal defects with a very high mortality.

CONCLUSIONS

All NSAIDs, both specific and nonspecific COX inhibitors, have renal side effects in the immediate post-natal period and should, therefore, be given with the utmost caution. NSAIDs given during pregnancy for the prevention of toxemia, polyhydramnios and premature labour may affect fetal renal function and structure. In animal experiments, IBU was not less nephrotoxic than INDO, as suggested recently by human premature neonates.

Comparison of the efficacy and adverse effects of nifedipine and indomethacin for the treatment of preterm labor

OBJECTIVE

To compare the effectiveness and adverse effects of nifedipine versus indomethacin in the treatment of preterm labor.

METHODS

In a randomized clinical trial, 79 women with labor pain at 26-33 weeks of gestation were treated with either oral nifedipine (n=40) or rectal indomethacin (n=39).

RESULTS

Twenty-three (59%) women in the indomethacin group, and 10 (25%) in the nifedipine group did not respond to treatment (P=0.002). None of the 16 and 30 women remaining in the indomethacin and nifedipine groups, respectively, delivered during the subsequent 48 hours. Of these remaining women, 1 (6.25%) in the indomethacin group and 4 (13.3%) in the nifedipine group delivered between 48 hours and 7 days (P=0.162). For the women who responded to treatment, the mean gestational age at time of delivery was 238.5±19.4 days and 246.4±15.4 days in the nifedipine and indomethacin groups, respectively (P=0.182). Seventeen (42.5%) women in the nifedipine group, and 11 (28.2%) in the indomethacin group showed adverse effects (P=0.184).

CONCLUSION

Indomethacin was less effective than nifedipine for the fast treatment of preterm labor. For women who responded to treatment within 2 hours, however, the delaying of delivery by indomethacin was similar to that by nifedipine.

[Indometacin: come back of a controversial tocolytic? Obstetrical point of view]

The main aim of tocolysis is to improve the health of newborns. Given the modest impact in terms of perinatal health of tocolysis we must emphasize the use of tocolytics which, equally effective, have fewer maternal side effects than beta-agonists and are devoid of potential complications for mother and the newborn. Inhibitors of prostaglandin synthesis and calcium antagonists of oxytocin seem to meet these criteria. The recent papers for the use of NSAIDs provide no fundamentally new scientific data. This therapy is potentially associated with severe neonatal complications and superiority to calcium channel blockers or antagonists of oxytocin in terms of prolongation of pregnancy is not established. It seems reasonable to reserve them for special situations by their severity, precocity of the age of gestation or by the ineffectiveness of other treatments. In practice, it is recommended not to use NSAIDs first line, beyond 32 weeks and treatment should be of short duration (less than 48 to 72 hours). Ideally, delivery should not occur within 48 hours after stopping treatment.

Metaanalysis of the effect of antenatal indomethacin on neonatal outcomes

OBJECTIVE

The objective of the study was to determine whether indomethacin used as a tocolytic agent is associated with adverse neonatal outcomes.

STUDY DESIGN

We used published guidelines of the Metaanalysis of Observational Studies in Epidemiology Group (MOOSE) to perform the metaanalysis. The search strategy used included computerized bibliographic searches of MEDLINE (1966-2005), PubMed (1966-2005), abstracts published in Obstetrics and Gynecology (1991-2005), abstracts published in Pediatric Research (1991-2005), and references of published manuscripts. Study inclusion criteria were publication in English, more than 30 deliveries less than 37 weeks' gestation, and meeting diagnostic criteria for individual neonatal outcomes. Exclusion criteria included case reports, case series, and multiple publications from the same author. Metaanalysis was performed using random effects model if there were more than 2 observational studies for a specific outcome. Eggers test was performed to exclude publication bias. Sensitivity analysis was performed to evaluate the effect of antenatal steroid exposure, gestation, and recent antenatal indomethacin exposure (duration of 48 hours or more between the last dose and delivery).

RESULTS

Fifteen retrospective cohort studies and 6 case-controlled studies met inclusion criteria. Antenatal indomethacin was associated with an increased risk of periventricular leukomalacia (odds ratio [OR], 2.0; 95% confidence interval [CI], 1.3-3.1). Recent exposure to antenatal indomethacin was associated with necrotizing enterocolitis (OR, 2.2; 95% CI; 1.1-4.2). Antenatal indomethacin was not associated with intraventricular hemorrhage, patent ductus arteriosus, respiratory distress syndrome, bronchopulmonary dysplasia, and mortality.

CONCLUSION

Antenatal indomethacin may be associated with an increased risk of periventricular leukomalacia and necrotizing enterocolitis in premature infants and therefore should be used judiciously for tocolysis.

Influence of labor on neonatal neutrophil apoptosis, and inflammatory activity

Neutrophil apoptosis is impaired in neonates, and this contributes to prolonged inflammation and tissue injury in infants after infection or trauma. In the present studies, we investigated whether labor generates mediators that further suppress apoptosis. We found that neutrophil apoptosis was reduced in neonates exposed to labor, when compared with infants delivered by cesarean section before labor. This was not due to alterations in caspase-3 or inhibitor of apoptosis protein-2 (IAP-2). In contrast, labor primed neutrophils to express tumor necrosis factor alpha (TNF-alpha), suggesting that proinflammatory mediators contribute to reduced apoptosis after labor. Eicosanoids generated via cyclooxygenase-2 (Cox-2) and lipoxygenase (Lox) also regulate neutrophil apoptosis. 15-Lox, which generates proapoptotic lipoxins, but not Cox-2, was greater in neutrophils before labor, relative to cells exposed to labor. Anti-inflammatory eicosanoids exert their effects in part via peroxisome proliferator-activated receptor gamma (PPAR-gamma). Expression of gelatinase-associated lipocalin and catalase, two markers of PPAR-gamma activity, were increased in neonatal neutrophils before labor, relative to cells exposed to labor. These findings suggest that the anti-inflammatory environment is maintained before labor, in part, by eicosanoids. Although increased neutrophil longevity after labor is important for host defense in the immediate newborn period, it may contribute to inflammatory or oxidative injury in susceptible infants.

The effects of indomethacin tocolysis on the postnatal response of the ductus arteriosus to indomethacin in extremely low birth weight infants

BACKGROUND

Antenal indomethacin reportedly decreases the responses of a symptomatic patent ductus arteriosus (sPDA) to postnatal indomethacin treatment. Whether a similar exposure affects the responses to indomethacin prophylaxis is unknown.

OBJECTIVE

To evaluate the clinical responsiveness of ductus arteriosus to indomethacin prophylaxis and to the treatment of sPDA in extremely low birth weight (ELBW) infants following indomethacin tocolysis.

METHODS

Retrospective cohort study of 58 ELBW infants whose mothers received indomethacin tocolysis (study) and 58 ELBW infants whose mothers did not (controls), matched by gender, gestational age (GA), birth weight and postnatal sPDA management (prophylaxis or early treatment).

RESULTS

Indomethacin was used as a tocolytic at a median dose of 250 mg, for a duration of 2 days, and ending 1 day before delivery. Study and control mothers were comparable in demographics, antenatal steroid use, cesarean delivery, but were different in the incidence of preeclampsia and preterm labor. Study and control infants were similar in birth weight, GA, indomethacin prophylaxis, early sPDA treatment, mortality, necrotizing enterocolitis, severe intraventricular hemorrhage and stage 3-5 retinopathy of prematurity. Seventeen of 43 study and 16 of 43 control infants who received indomethacin prophylaxis developed sPDA and were combined with early treatment sPDA infants (15 to each group). Two of 32 study and two of 31 control infants underwent surgical ligation whereas the remaining were treated with indomethacin. Sixteen of 30 (53%) and 13 of 29 (45%) were successfully treated and did not require ligation. Study infants were divided according to their mothers' indomethacin total dose (28 infants received <or=225 mg and 30 infants received >225 mg). Both subgroups were demographically and clinically comparable and their response to indomethacin prophylaxis and treatment were similar.

CONCLUSION

In ELBW infants, exposure to indomethacin tocolysis does not affect the clinical responsiveness of the ductus arteriosus to prophylaxis or that of the sPDA to indomethacin treatment.

Effects of drugs on the fetus

Most drugs are not labelled for use in pregnancy. Consequently, large numbers of women expose their fetus to potential risks, either because they do not know that they are pregnant or because they require treatment for gestational pathologies. The present review focuses on drug classes for which the risk:benefit ratio during pregnancy has been discussed recently based on human data. Selective serotonin reuptake inhibitors have gained wide acceptance in the treatment of depression and data on their risk for neonatal adaptation after late exposure are reviewed. Angiotensin converting enzyme inhibitors and angiotensin II receptors antagonists interact with the renin-angiotensin system, although with different mechanisms, and might cause severe fetal tubular dysgenesis. Non-steroidal anti-inflammatory and antiviral drugs and recreational drugs are also presented.

In situ inhibition of uterine activity by indomethacin: possible relevance to preterm labor prevention after fetal surgery

PURPOSE

This report is an analysis of the effects of local indomethacin delivery on uterine activity in vitro.

METHODS

Isolated strips of time-dated pregnant rats' myometrium were placed within controlled tissue baths. Spontaneous muscular activity was recorded by a force transducer connected to a polygraph at cumulative concentrations of indomethacin. Statistical analysis was by single-factor analysis of variance (ANOVA), with P values of less than.05 considered significant.

RESULTS

Within a narrow concentration range, the effects of indomethacin on frequency and amplitude of myometrial contractions were nonmonotonic, with an increase in frequency at levels that began to depress amplitude. However, both amplitude and frequency were significantly depressed and eventually totally abolished at most concentrations studied (P <.05).

CONCLUSIONS

Indomethacin administered in situ consistently inhibits or completely arrests overall myometrial activity. The concept of local myometrial delivery of indomethacin, possibly via slow release systems, may prove clinically useful as an adjuvant to its systemic administration in preterm labor prevention after fetal surgery, warranting further trials in vivo.

Persistent pulmonary hypertension in a premature newborn after 16 hours of antenatal indomethacin exposure

Premature constriction of the fetal ductus arteriosus has been described with long-term indomethacin therapy, but not in fetuses who have been exposed to the drug for less than 72 hours. The sensitivity of the ductus to extended indomethacin tocolysis increases with advancing gestational age. For this reason, it is recommended that indomethacin not be used beyond 31 weeks of gestation. In the present case the gestational age of the patient was 27 weeks and the period of indomethacin exposure was only 16 hours. Our observations of pulmonary hypertension in this case suggest that administration of indomethacin even hours before delivery can significantly affect the ductus arteriosus and the pulmonary vasculature.

Comparison of nonselective cyclo-oxygenase (COX) inhibitor and selective COX-2 inhibitors on preimplantation loss, postimplantation loss and duration of gestation: an experimental study

Comparison of effect of three cyclo-oxygenase (COX) inhibitors, indomethacin, nimesulide and celecoxib, on the following were assessed: preimplantation loss, postimplantation loss and duration of gestation in Wistar rats. Indomethacin (2.5 and 10 mg/kg), nimesulide (10 and 40 mg/kg) and celecoxib (10 and 40 mg/kg) were administered by gavage daily from days 1-7 for preimplantation loss studies and from day 13 to completion of gestation for postimplantation and duration of gestation studies. Number of animals in each group was six. Preimplantation loss was calculated by subtracting number of implantation sites from number of luteal spots and postimplantation loss was calculated by noting the difference between implantation sites and pups delivered. The higher doses of the three drugs were shown to increase significantly the preimplantation loss, while all the doses of three drugs produced a significant increase in postimplantation loss. Number of animals crossing upper limit of 23-day normal gestation period in Wistar rats was increased in the higher doses. At comparable dose levels, there was no significant difference among the three drugs.

Expression of prostanoid receptors in human lower segment pregnant myometrium

Prostanoids, especially prostaglandin (PG) E(2), are important mediators of uterine relaxation and contractions during gestation and parturition. Inhibitors of PG formation as well as PG analogues are used to modulate uterine tonus. So far, only limited data are available regarding the expression of prostanoid receptors in human pregnant myometrium. In the present study, the expression of the receptors for PGE(2) (EP1, EP2, EP3, EP4), PGF(2alpha) (FP), prostacyclin (IP), and thromboxane A(2) (TP) in human pregnant myometrium was studied by RT-PCR, in situ hybridization and immunohistochemistry. Myometrial tissue was obtained from five women at term and not in labour and from two women who delivered preterm. Tissue specimens were excised from the upper edge of the transverse lower uterine segment incision. In all tissues analysed, EP1, EP2, EP3, EP4, FP, TP and IP receptor mRNA and protein was detected. mRNA expression for PGD(2) (DP) receptor was not detected in the majority of tissue specimens. EP1, EP2, EP4, IP, TP and FP receptor protein was detected on myometrial smooth muscle cells, whereas EP3 receptor protein was only expressed by stromal and endothelial cells. In situ hybridization experiments yielded similar results. The expression of the EP2 receptor mRNA was inversely related to gestational age. We suggest that the contractile effect of PGE(2) at term is probably mediated directly by the EP1 receptor expressed in myometrial smooth muscle cells and indirectly by the EP3 receptor expressed in stromal cells and a decrease in EP2 receptor expression.

Tocolytic treatment for the management of preterm labor: a review of the evidence

OBJECTIVE

Preterm labor is often a prelude to early births and the significant attendant burden of infant morbidity and mortality. Treatment consists of bedrest, hydration, pharmacologic interventions, and combinations of these. We systematically reviewed the effectiveness of tocolytics to stop uterine contractions (first-line therapy) or maintain quiescence (maintenance therapy). Our objective was to evaluate the evidence on the benefits and harms of five classes of tocolytic therapy for treating uterine contractions related to preterm labor--beta-mimetics, calcium channel blockers, magnesium, nonsteroidal anti-inflammatory agents, and ethanol.

STUDY DESIGN

Reports of randomized controlled trials and other study designs in English, French, and German identified from searches of MEDLINE, EMBASE, specialized databases, bibliographies of review articles, unpublished literature, and discussions with investigators in the field were identified. Studies on women with preterm labor between 1966 and February 1999 that met our inclusion criteria were included. Through dual review, we abstracted the following information: study design and masking; definitions of preterm labor and successful tocolysis; patient inclusion/exclusion characteristics; patient demographic characteristics; drug and cointerventions; and numerous birth, maternal, and neonatal outcome measures.

RESULTS

Of the 256 articles evaluated, we abstracted data from 60 first-line and 15 maintenance studies. Of these, 16 first-line and 8 maintenance studies met more stringent requirements for meta-analyses. Studies of first-line tocolysis (grade Fair) reveal a mixed outcome pattern with small improvement in pregnancy prolongation and birth at term relative to placebo. Data were insufficient to show directly a beneficial effect on neonatal morbidity or mortality. Ethanol was less beneficial than, and beta-mimetics were not superior to, other tocolytic options. Maintenance tocolytics (grade Poor) showed no improvements in birth or infant outcomes relative to placebo; these results were confirmed through meta-analysis. In contrast to other tocolytic treatments, maternal harms from beta-mimetics were rated High; all tocolytics were rated as Low risk for short-term neonatal harms.

CONCLUSIONS

Management of uterine contractions with first-line tocolytic therapy can prolong gestation. Among the tocolytics, however, beta-mimetics appear not to be better than other drugs and pose significant potential harms for mothers; ethanol remains an inappropriate therapy. Continued maintenance tocolytic therapy has little or no value.

COX-2 inhibitors and their role in gynecology

This review summarizes current knowledge about the roles of cyclooxygenases and prostaglandins in reproductive medicine. With the development of COX-2 specific inhibitors, new therapeutic options are available to obstetricians and gynecologists, offering better-tolerated alternatives to conventional NSAIDs. The analgesic effectiveness of COX-2 specific inhibitors is well established, and they are already in use in a range of painful conditions. Both celecoxib and valdecoxib are indicated for the treatment of primary dysmenorrhea, and may be effective in postoperative pain, including hysterectomy, and pain associated with endometriosis. There is also speculation that COX-2 specific inhibitors may be effective tocolytic agents without the risks to the fetus seen with conventional NSAIDs. The role of COX-2 in oncogenesis is also under investigation, and COX-2 specific inhibitors may eventually be used in the prevention and treatment of gynecologic malignancies.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians Learning Objectives: After completion of this article, the reader will be able to describe the two types of cylooxygenase enzymes (COX), to list the effects and side effects of NSAIDs and COX-2 medications, and to outline the various changes in COX expression during pregnancy.

Preterm labour

Studies in the past year have clarified the roles of inflammatory mediators in preterm labour. Exploration of possible genetic predisposition is just beginning. Ultrasound measurement of cervical length has the potential to predict women at risk of preterm delivery several weeks before it occurs. Biochemical testing such as fetal fibronectin can possibly increase its predictive value and differentiate true preterm labour from more innocent preterm contractions. The use of antibiotics for preterm premature rupture of membranes has been clarified with the ORACLE I trial, which shows health benefits for the neonate with the use of erythromycin, whereas antibiotics do not seem to play a beneficial role in spontaneous preterm labour without evidence of clinical infection. There have been further studies suggesting that agents other than beta-agonists are preferable for acute tocolysis and that repeated doses of corticosteroids should be used with caution.