Prostaglandins for Postpartum Hemorrhage: Pharmacology, Application, and Current Opinion

Uterine Rupture During Induced Abortion in the Second Trimester

Termination of pregnancy (TOP) in the second trimester accounts for less than 10% of all abortion procedures. Although it can be obtained by a surgical procedure, medical TOP is an effective and safe option. Prostaglandins have been used for cervical ripening in the second trimester but in the presence of uterine scars, the risk of uterine rupture rises. Given the increasing rate of cesarean deliveries worldwide, it is important to be aware of the risks associated with TOP in women with previous uterine scars. We describe a rare case, in a patient with a prior cesarean delivery, of a uterine rupture in a TOP at 20 weeks with a regimen of mifepristone-misoprostol and sulprostone.

Prostaglandin Injection for Myoma Expulsion (PRIME): Case Series of a Novel Approach to Hysteroscopic Resection of FIGO Type 2 Myomas

STUDY OBJECTIVE

To evaluate the use of dilute carboprost tromethamine injection at the endometrium/myoma junction during hysteroscopy to facilitate myoma expulsion and removal in a single procedure.

DESIGN

Case series.

SETTING

Single high-volume academic medical center.

PATIENTS

Seven patients aged 32 to 51 years old with FIGO type 2 uterine myomas and symptoms of abnormal uterine bleeding or infertility undergoing hysteroscopic resection with a morcellation device from November 2022 to July 2023.

INTERVENTION

Dilute injection of carboprost tromethamine (10 µg/mL) at time of hysteroscopic myomectomy.

MEASUREMENTS AND MAIN RESULTS

The main outcome measure was ability to complete the hysteroscopic myomectomy in a single procedure using a hysteroscopic morcellator. Secondary outcomes included total operative time, fluid deficit, and postoperative pharmacologic side effects and/or surgical complications. Among our 7 patients, all had successful single procedure complete resections of myomas ranging from 0.9 to 4.6 cm in maximal diameter. Average operative time was 30 minutes, and average fluid deficit was approximately 839 mL. The carboprost dosages used ranged from 30 to 180 µg. One patient experienced prolonged postoperative nausea and vomiting that resolved with antiemetics. One patient experienced postoperative endometritis that improved with antibiotics.

CONCLUSION

In this pilot study, injection of dilute carboprost intraoperatively facilitated one-step hysteroscopic myomectomy of FIGO 2 myomas, via enhanced extrusion of the intramural portion of the fibroid into the uterine cavity, with both short operative times and acceptable fluid deficits.

Postpartum Haemorrhage and Carboprost for Its Prevention: A Narrative Review

The most frequent and harmful side effect of childbirth is obstetric haemorrhage. Postpartum haemorrhage (PPH) remains the primary cause of maternal mortality worldwide. Most PPH-related deaths take place in the first 24 hours of life. It is commonly believed that prompt diagnosis and treatment could avert the majority of PPH-related deaths. The rapid transition of haemorrhage from the remunerated to the decompensated stage is frequently overlooked. For this reason, anticipation, early detection, and management are crucial to reducing the risk of severe PPH (SPPH) or improving its clinical outcomes. Third-stage labour is a high-risk period for PPH. Active management of PPH is an effective intervention to lessen the incidence of PPH and has been promoted as a means of lowering fatality rates. Currently, prostaglandins (PGs) are advised as a second-line uterotonic medication. Strong uterotonic drugs such as carboprost tromethamine play a physiological role in human parturition, helping to birth the fetus and controlling PPH. Prostaglandins have a major effect on uterine tone, which minimizes blood loss. Their discovery, together with the use of their counterparts as uterotonics, has improved PPH management. In order to assist healthcare professionals in managing PPH promptly and minimizing adverse effects on both the mother and the newborn, this review will describe the causes of the disorder, the strategies that have been tried to treat it, and the role that carboprost plays in preventing it.

Animal models of postpartum hemorrhage

Postpartum hemorrhage (PPH)-heavy bleeding following childbirth-is a leading cause of morbidity and mortality worldwide. PPH can affect individuals regardless of risks factors and its incidence has been increasing in high-income countries including the United States. The high incidence and severity of this childbirth complication has propelled research into advanced treatments and alternative solutions for patients facing PPH; however, the development of novel treatments is limited by the absence of a common, well-established and well-validated animal model of PPH. A variety of animals have been used for in vivo studies of novel therapeutic materials; however, each of these animals differs considerably from the anatomy and physiology of a postpartum woman, and the methods used for achieving a postpartum hemorrhagic condition vary widely. Here we critically evaluate the various animal models of PPH presented in the literature and propose additional and alternative methods for modeling PPH in in vivo studies. We highlight how current animal models successfully or unsuccessfully mimic the anatomy and physiology of a postpartum woman and how this may impact treatment development. We aim to equip researchers with the necessary background information to select appropriate animal models for their research related to PPH solutions, while supporting the goals of refinement, reduction and replacement (3Rs) in preclinical animal studies.

Structures of human prostaglandin F2α receptor reveal the mechanism of ligand and G protein selectivity

Prostaglandins and their receptors regulate various physiological processes. Carboprost, an analog of prostaglandin F2α and an agonist for the prostaglandin F2-alpha receptor (FP receptor), is clinically used to treat postpartum hemorrhage (PPH). However, off-target activation of closely related receptors such as the prostaglandin E receptor subtype EP3 (EP3 receptor) by carboprost results in side effects and limits the clinical application. Meanwhile, the FP receptor selective agonist latanoprost is not suitable to treat PPH due to its poor solubility and fast clearance. Here, we present two cryo-EM structures of the FP receptor bound to carboprost and latanoprost-FA (the free acid form of latanoprost) at 2.7 Å and 3.2 Å resolution, respectively. The structures reveal the molecular mechanism of FP receptor selectivity for both endogenous prostaglandins and clinical drugs, as well as the molecular mechanism of G protein coupling preference by the prostaglandin receptors. The structural information may guide the development of better prostaglandin drugs.

Prostaglandin and prostaglandin receptors: present and future promising therapeutic targets for pulmonary arterial hypertension

BACKGROUND

Pulmonary arterial hypertension (PAH), Group 1 pulmonary hypertension (PH), is a type of pulmonary vascular disease characterized by abnormal contraction and remodeling of the pulmonary arterioles, manifested by pulmonary vascular resistance (PVR) and increased pulmonary arterial pressure, eventually leading to right heart failure or even death. The mechanisms involved in this process include inflammation, vascular matrix remodeling, endothelial cell apoptosis and proliferation, vasoconstriction, vascular smooth muscle cell proliferation and hypertrophy. In this study, we review the mechanisms of action of prostaglandins and their receptors in PAH.

MAIN BODY

PAH-targeted therapies, such as endothelin receptor antagonists, phosphodiesterase type 5 inhibitors, activators of soluble guanylate cyclase, prostacyclin, and prostacyclin analogs, improve PVR, mean pulmonary arterial pressure, and the six-minute walk distance, cardiac output and exercise capacity and are licensed for patients with PAH; however, they have not been shown to reduce mortality. Current treatments for PAH primarily focus on inhibiting excessive pulmonary vasoconstriction, however, vascular remodeling is recalcitrant to currently available therapies. Lung transplantation remains the definitive treatment for patients with PAH. Therefore, it is imperative to identify novel targets for improving pulmonary vascular remodeling in PAH. Studies have confirmed that prostaglandins and their receptors play important roles in the occurrence and development of PAH through vasoconstriction, vascular smooth muscle cell proliferation and migration, inflammation, and extracellular matrix remodeling.

CONCLUSION

Prostacyclin and related drugs have been used in the clinical treatment of PAH. Other prostaglandins also have the potential to treat PAH. This review provides ideas for the treatment of PAH and the discovery of new drug targets.

Effects of Heliotropium indicum L. on Uterine Involution and Its Underlying Mechanisms: an in vivo and in vitro Study

OBJECTIVE

To investigate the effect of Heliotropium indicum L. (H. indicum L.) on uterine involution and its underlying mechanisms in both in vivo and in vitro study.

METHODS

For in vivo studies, postpartum rats were randomly divided into 2 groups (n=24 for each): control group and treated group which were orally and daily administered with ethanolic extract of H. indicum L. (250 mg/kg body weight) until day 5 of postpartum. Uteri were collected for analysis of weight, cross-sectional area, collagen cross-sectional area, and collagen content on postpartum day 1, 3, and 5 (n=8 for each) from both groups. Blood samples were collected for hepatotoxicity and 17β-estradiol (E2) measurement. For in vitro studies, the extract effects on uterine contraction at half maximum effective concentration of 2.50 mg/mL were studied in organ bath system for at least 20 min.

RESULTS

Uterine parameters were significantly decreased after treated with extract of H. indicum L. (P<0.05). H. indicum L. extract significantly accelerated the reduction of those parameters and significantly decreased E2 (P<0.05). The extract facilitated uterine involution with no hepatotoxicity. H. indicum L. extract significantly stimulated uterine contraction (P<0.05) and synergized with oxytocin, prostaglandin and its precursor, linoleic acid. By investigating the different sequencing of the extract with the additional stimulants (added before or after), the two showed antagonistic effects, but still showed potentiated force when compared with control (without the stimulants).

CONCLUSIONS

The underlying mechanisms by which H. indicum L. facilitated uterine involution might be due to reducing E2 which induces collagenase activity, leading to decreases in uterine weight and size and stimulating uterine contraction. Our study provides new findings for future drug development for facilitating uterine involution with H. indicum L.

Association of adverse outcomes with three-tiered risk assessment tool for obstetrical hemorrhage

BACKGROUND

Guidelines promote stratification for the risk for postpartum hemorrhage among parturients, although the evidence for the associated differential morbidity among the groups remains inconsistent among published reports.

OBJECTIVE

Using the California Maternal Quality Care Collaborative schema modified by the American College of Obstetrics and Gynecology, we compared the composite maternal hemorrhagic outcome and the composite neonatal adverse outcome among singletons who were categorized after delivery by the researchers as low-, medium-, or high-risk for postpartum hemorrhage. We hypothesized that the composite outcomes would be significantly different among the individuals in the different 3-tiered categories.

STUDY DESIGN

This was a retrospective cohort study of all singleton parturients with a gestational age of at least 14 weeks who delivered at a single site within 1 year. The composite maternal hemorrhagic outcome included any of the following: estimated blood loss ≥1000 mL, use of uterotonics (excluding prophylactic oxytocin) or Bakri balloon, surgical management of postpartum hemorrhage, blood transfusion, hysterectomy, thromboembolism, admission to the intensive care unit, or maternal death. The composite neonatal adverse outcome included Apgar score <7 at 5 minutes, birth injury, bronchopulmonary dysplasia, intraventricular hemorrhage, neonatal seizure, sepsis, ventilation > 6 hrs., brachial plexus palsy, hypoxic-ischemic encephalopathy, or neonatal death. Multivariable Poisson regression models with robust error variance were used to estimate the adjusted relative risks with 95% confidence intervals.

RESULTS

Of the 4544 deliveries in the study period, 4404 (96.7%) met the inclusion criteria, and among them, 1745 (39.6%) were categorized as low, 1376 (31.2%) as medium, and 1283 (29.1%) as high risk. Overall, 941 (21.4%) participants experienced the composite maternal hemorrhagic outcome with 285 (16.4%) of those being in the low-risk group, 319 (23.2%) in the medium-risk group, and 337 (26.3%) in the high-risk group. Among all parturients, 95.7% in the low-, 89.4% in the medium-, and 85.3% in the high-risk group neither had an estimated blood loss or a quantified blood loss ≥1000 mL nor were transfused. After multivariable adjustment and when compared with the low-risk group, there was a significantly higher risk for the composite maternal hemorrhagic outcome in the medium-risk group (adjusted relative risk, 1.23; 95% confidence interval, 1.05-1.43) and in the high-risk group (adjusted relative risk, 1.51; 95% confidence interval, 1.31-1.75). Overall, 366 newborns (8.4%) developed the composite neonatal adverse outcome with 76 (4.2%) in of those being in the low-risk group, 153 (11.3%) in the medium-risk group, and 140 (11.1%) in the high-risk group. After multivariable adjustment and when compared with the low-risk group, there were no significant differences in the composite neonatal adverse outcome in the medium- (adjusted relative risk, 1.27; 95% confidence interval, 0.97-1.68) or the high-risk group (adjusted relative risk, 1.29; 95% confidence interval, 0.98-1.68).

CONCLUSION

Although 8 of 10 parturients categorized as high risk neither had blood loss ≥1000 mL nor underwent transfusion, the risk stratification provides information regarding the composite maternal hemorrhagic outcome.

Impact of polyphenols on heart failure and cardiac hypertrophy: clinical effects and molecular mechanisms

Polyphenols are abundant in regular diets and possess antioxidant, anti-inflammatory, anti-cancer, neuroprotective, and cardioprotective effects. Regarding the inadequacy of the current treatments in preventing cardiac remodeling following cardiovascular diseases, attention has been focused on improving cardiac function with potential alternatives such as polyphenols. The following online databases were searched for relevant orginial published from 2000 to 2023: EMBASE, MEDLINE, and Web of Science databases. The search strategy aimed to assess the effects of polyphenols on heart failure and keywords were "heart failure" and "polyphenols" and "cardiac hypertrophy" and "molecular mechanisms". Our results indicated polyphenols are repeatedly indicated to regulate various heart failure-related vital molecules and signaling pathways, such as inactivating fibrotic and hypertrophic factors, preventing mitochondrial dysfunction and free radical production, the underlying causes of apoptosis, and also improving lipid profile and cellular metabolism. In the current study, we aimed to review the most recent literature and investigations on the underlying mechanism of actions of different polyphenols subclasses in cardiac hypertrophy and heart failure to provide deep insight into novel mechanistic treatments and direct future studies in this context. Moreover, due to polyphenols' low bioavailability from conventional oral and intravenous administration routes, in this study, we have also investigated the currently accessible nano-drug delivery methods to optimize the treatment outcomes by providing sufficient drug delivery, targeted therapy, and less off-target effects, as desired by precision medicine standards.

Preventing postpartum hemorrhage with combined therapy rather than oxytocin alone

Postpartum hemorrhage is the leading cause of maternal morbidity and mortality worldwide, with uterine atony estimated to account for 70% to 80% of cases, thereby remaining the single most common cause. Pharmacotherapy remains the first-line preventative therapy for postpartum hemorrhage. These therapies may be single (oxytocin, carbetocin, methylergonovine, ergometrine, misoprostol, prostaglandin analogs, or tranexamic acid) or combination therapies, acting in an additive, infra-additive, or synergistic fashion to prevent postpartum hemorrhage. Evidence is strong for the use of oxytocin, the first-line uterotonic agent in the United States for prevention of postpartum hemorrhage. Although carbetocin, a long-acting analog of oxytocin, is not yet available for use in the United States, it is likely the most effective single pharmacologic therapy for prevention of postpartum hemorrhage and need for additional uterotonics. Use of second-line uterotonics such as methylergonovine, misoprostol, and carboprost in combination with oxytocin has an additive or synergistic effect and a greater risk reduction for postpartum hemorrhage prevention compared with oxytocin alone. Therefore, combined therapy rather than oxytocin alone should be advised for preventing postpartum hemorrhage. Tranexamic acid has been found to be both effective and safe for decreasing maternal mortality in women with postpartum hemorrhage, and prophylactic use of tranexamic acid may decrease the need for packed red blood cell transfusions and/or uterotonics. The WOMAN-2 Trial, designed to assess if tranexamic acid prevents postpartum hemorrhage in women with moderate to severe anemia undergoing vaginal delivery, is currently recruiting participants. The additive, infra-additive, or synergistic action of oxytocin in combination with other second-line therapies deserves further study.

Nalbuphine May Be Superior to Sufentanil in Relieving Postcesarean Uterine Contraction Pain in Multiparas: A Retrospective Cohort Study

Purpose

Postcesarean pain remains a major complaint from puerperium women who have undergone cesarean section, especially uterine contraction induced visceral pain. The optimal opioid for pain relief after cesarean section (CS) is still unclear. The goal of this study was to compare the analgesic effect of Nalbuphine to Sufentanil in patients who underwent CS.

Patients and Methods

In this single-center retrospective cohort study, we included patients who received Nalbuphine or Sufentanil Patient-Controlled Intravenous Analgesia (PCIA) after CS between 1 January 2018 and 30 November 2020. Data on a Visual Analog Scale (VAS) at uterine contraction, at rest, and at movement, analgesic consumption, and side effects were collected. We performed logistic regression to identify predictors of severe uterine contraction pain.

Results

A total of 674 patients were identified in the unmatched cohort, and 612 patients in the matched one. Compared to the Sufentanil group, lower VAS-contraction was recorded in the Nalbuphine group in both the unmatched and matched cohorts, the mean difference (MD) on POD1 was 0.35 (95% CI: 0.17 to 0.54, p<0.001) and 0.28 (95% CI: 0.08 to 0.47, p<0.001), respectively, and the MD of POD2 was 0.12 (95% CI: 0.03 to 0.40, P=0.019) and 0.12 (95% CI: 0.03 to 0.41, P=0.026), respectively. On POD1 but not POD2, VAS-movement was lower in the Nalbuphine group as compared to the Sufentanil group. No difference was found between VAS-rest on POD1 and POD2 in both unmatched and matched cohorts. Less analgesic consumption, and side effects were recorded in the Nalbuphine group. Logistic regression indicated that multipara and analgesic consumption were risk factors for severe uterine contraction pain. In subgroup analysis, VAS-contraction was meaningfully reduced in the Nalbuphine group compared with the Sufentanil group in multipara patients, but not primiparas.

Conclusion

Compared to Sufentanil, Nalbuphine may provide better analgesia on uterine contraction pain. The superior analgesia may only exhibit in multiparas.

Prostaglandin F2α evokes vasoconstrictor and vasodepressor activities that are both independent of the F prostanoid receptor

The F prostanoid receptor (FP), which accounts for the therapeutic effect of PGF_2α in uterine atony that leads to postpartum hemorrhage and maternal morbidity, could possibly mediate vasoconstrictor effect in small or resistance arteries to elevate blood pressure that limits the clinical use of the agent in patients with cardiovascular disorders. This study aimed to test the above hypothesis with genetically altered mice. Ex vivo and in vivo experiments were performed on control wild-type (WT) mice and mice with deficiencies in FP (FP^-/- ) or thromboxane (Tx)-prostanoid receptor (the original receptor of TxA₂ ; TP^-/- ), and/or those with an additional deficiency in E prostanoid receptor-3 (one of the vasoconstrictor receptors of PGE₂ ; EP3^-/- ). Here, we show that PGF_2α indeed evoked vasoconstrictor responses in the above-mentioned tissues of WT mice, which were however unaltered by FP^-/- . Interestingly, such contractile responses were reversed into dilations by TP^-/- /EP3^-/- . A similar pattern of results was observed with the pressor effect of PGF_2α under in vivo conditions. However, TP^-/- alone (which could largely remove the contractile responses) did not result in relaxation to PGF_2α . Also, either the ex vivo vasodilator effect or the in vivo depressor response of PGF_2α obtained after the removal of TP and EP3-mediated actions was unaltered by FP^-/- . Therefore, both the ex vivo vasoconstrictor action in small or resistance arteries and the systemic pressor effect of PGF_2α can reflect vasoconstrictor activities derived from the non-FP receptors TP and EP3 outweighing a concurrently activated dilator effect, which is again independent of FP.