FP and EP2 prostanoid receptor agonist drugs and aqueous humor outflow devices for treating ocular hypertension and glaucoma.

Prostaglandin (PG) receptors represent important druggable targets due to the many diverse actions of PGs in the body. From an ocular perspective, the discovery, development, and health agency approvals of prostaglandin F (FP) receptor agonists (FPAs) have revolutionized the medical treatment of ocular hypertension (OHT) and glaucoma. FPAs, such as latanoprost, travoprost, bimatoprost, and tafluprost, powerfully lower and control intraocular pressure (IOP), and became first-line therapeutics to treat this leading cause of blindness in the late 1990s to early 2000s. More recently, a latanoprost-nitric oxide (NO) donor conjugate, latanoprostene bunod, and a novel FP/EP3 receptor dual agonist, sepetaprost (ONO-9054 or DE-126), have also demonstrated robust IOP-reducing activity. Moreover, a selective non-PG prostanoid EP2 receptor agonist, omidenepag isopropyl (OMDI), was discovered, characterized, and has been approved in the United States, Japan and several other Asian countries for treating OHT/glaucoma. FPAs primarily enhance uveoscleral (UVSC) outflow of aqueous humor (AQH) to reduce IOP, but cause darkening of the iris and periorbital skin, uneven thickening and elongation of eyelashes, and deepening of the upper eyelid sulcus during chronic treatment. In contrast, OMDI lowers and controls IOP by activation of both the UVSC and trabecular meshwork outflow pathways, and it has a lower propensity to induce the aforementioned FPA-induced ocular side effects. Another means to address OHT is to physically promote the drainage of the AQH from the anterior chamber of the eye of patients with OHT/glaucoma. This has successfully been achieved by the recent approval and introduction of miniature devices into the anterior chamber by minimally invasive glaucoma surgeries. This review covers the three major aspects mentioned above to highlight the etiology of OHT/glaucoma, and the pharmacotherapeutics and devices that can be used to combat this blinding ocular disease.

Prostaglandin F2α receptor antagonist attenuates LPS-induced systemic inflammatory response in mice.

Although it is known that prostaglandin (PG) F2α level is elevated in the plasma of patients with sepsis, the roles of PGF2α is still unknown. We aimed to clarify the roles of PGF2α in the regulation of lipopolysaccharide (LPS)-induced systemic inflammation. At 24 hours after LPS administration, neutrophil infiltration in peritoneal cavity, the mRNA expression of pro-inflammatory cytokines such as tumor necrosis factor-α, interleukin (IL)-1ß, IL-6, and macrophage inflammatory protein-2, and tissue damages in lung, liver, and kidney were all increased. Inhibition of FP receptors significantly decreased LPS-induced neutrophil infiltration and lowered the mRNA expression of the pro-inflammatory cytokines. At 6 hour after LPS administration, the level of anti-inflammatory cytokine, IL-10 in peritoneal lavage fluid was higher than that in naïve mice. Inhibition of FP receptors in these mice increased IL-10 level further. Stimulation of isolated peritoneal neutrophils by LPS increased the gene expression of IL-10, which was further increased by AL8810 treatment. Administration of an anti-IL-10 antibody antagonized the AL8810-decreased mRNA expression of pro-inflammatory cytokines and tissue damages. These results indicate that inhibition of FP receptors by AL8810 attenuated LPS-induced systemic inflammation in mice via enhanced IL-10 production.

The antagonism of prostaglandin FP receptors inhibits the evolution of spreading depolarization in an experimental model of global forebrain ischemia.

Spontaneous, recurrent spreading depolarizations (SD) are increasingly more appreciated as a pathomechanism behind ischemic brain injuries. Although the prostaglandin F2α - FP receptor signaling pathway has been proposed to contribute to neurodegeneration, it has remained unexplored whether FP receptors are implicated in SD or the coupled cerebral blood flow (CBF) response. We set out here to test the hypothesis that FP receptor blockade may achieve neuroprotection by the inhibition of SD. Global forebrain ischemia/reperfusion was induced in anesthetized rats by the bilateral occlusion and later release of the common carotid arteries. An FP receptor antagonist (AL-8810; 1 mg/bwkg) or its vehicle were administered via the femoral vein 10 min later. Two open craniotomies on the right parietal bone served the elicitation of SD with 1 M KCl, and the acquisition of local field potential. CBF was monitored with laser speckle contrast imaging over the thinned parietal bone. Apoptosis and microglia activation, as well as FP receptor localization were evaluated with immunohistochemistry. The data demonstrate that the antagonism of FP receptors suppressed SD in the ischemic rat cerebral cortex and reduced the duration of recurrent SDs by facilitating repolarization. In parallel, FP receptor antagonism improved perfusion in the ischemic cerebral cortex, and attenuated hypoemic CBF responses associated with SD. Further, FP receptor antagonism appeared to restrain apoptotic cell death related to SD recurrence. In summary, the antagonism of FP receptors (located at the neuro-vascular unit, neurons, astrocytes and microglia) emerges as a promising approach to inhibit the evolution of SDs in cerebral ischemia.

Influence of omega-3 fatty acids on bovine luteal cell plasma membrane dynamics.

Fish oil is a rich source of omega-3 fatty acids which disrupt lipid microdomain structure and affect mobility of the prostaglandin F2α (FP) receptor in bovine luteal cells. The objectives of this study were to determine the effects of individual omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on 1) membrane fatty acid composition, 2) lipid microdomain structure, and 3) lateral mobility of the FP receptor in bovine luteal cells. Ovaries were collected from a local abattoir (n=5/experiment). The corpus luteum was resected and enzymatically digested using collagenase to generate a mixed luteal cell population. In all experiments, luteal cells were treated with 0, 1, 10 or 100µM EPA or DHA for 72h to allow incorporation of fatty acids into membrane lipids. Results from experiment 1 show that culturing luteal cells in the presence of EPA or DHA increased these luteal fatty acids. In experiment 2, both EPA and DHA increased spatial distribution of lipid microdomains in a dose-dependent manner. Single particle tracking results from experiment 3 show that increasing both EPA and DHA concentrations increased micro- and macro-diffusion coefficients, increased domain size, and decreased residence time of FP receptors. Collectively, results from this study demonstrate similar effects of EPA and DHA on lipid microdomain structure and lateral mobility of FP receptors in cultured bovine luteal cells. Moreover, only 10µM of either fatty acid was needed to mimic the effects of fish oil.

Selective modulation of the prostaglandin F2α pathway markedly impacts on endometriosis progression in a xenograft mouse model.

STUDY HYPOTHESIS: Selective activation or blockade of the prostaglandin (PG) F2α receptor (FP receptor) affects ectopic endometrial tissue growth and endometriosis development. STUDY FINDING: FP receptor antagonists might represent a promising approach for the treatment of peritoneal endometriosis. WHAT IS KNOW ALREADY: Eutopic and ectopic endometrium from women with endometriosis exhibit higher expression of key enzymes involved in the PGF2α biosynthetic pathway. It has also been shown that the PGF2α-FP receptor interaction induces angiogenesis in human endometrial adenocarcinoma. STUDY DESIGN, SAMPLES/MATERIALS, METHODS: For this study, a mouse model of endometriosis was developed by inoculating human endometrial biopsies into the peritoneal cavity of nude mouse (n = 15). Mice were treated with AL8810 (FP receptor antagonist), Fluprostenol (FP receptor agonist) or PBS. Endometriosis-like lesions were collected and analysed for set of markers for angiogenesis, tissue remodelling, apoptosis, cell proliferation and capillary formation using qPCR and immunohistochemistry. MAIN RESULTS AND THE ROLE OF CHANCE: We found that selective inhibition of the FP receptor with a specific antagonist, AL8810, led to a significant decline in the number (P < 0.01) and size of endometriosis-like lesions (P < 0.001), down-regulated the expression of key mediators of tissue remodelling (MMP9, P < 0.05) and angiogenesis (VEGF, P < 0.01) and up-regulated the pro-apoptotic factor (Bax, P < 0.01) as compared with controls. Immunohistochemical analyses further showed a marked decrease in cell proliferation and capillary formation in endometrial implants from AL8810-treated mice, as determined by proliferating cell nuclear antigen (PCNA) and von Willebrand factor (vWF) immunostaining, respectively. Moreover, Fluprostenol, a selective FP receptor agonist, showed the opposite effects. LIMITATIONS, REASONS FOR CAUTION: We carried out this study in nude mice, which have low levels of endogenous estrogens which may affect the lesion growth. Caution is required when interpreting these results to women. WIDER IMPLICATIONS OF THE FINDINGS: This study extends the role of PG signalling in endometriosis pathogenesis and points towards the possible relevance of selective FP receptor antagonism as a targeted treatment for endometriosis. LARGE SCALE DATA: Not Applicable. STUDY FUNDING AND COMPETING INTERESTS: This work was supported by grant MOP-123259 to the late Dr Ali Akoum from the Canadian Institutes for Health Research. The authors have no conflict of interest.

Prostaglandin F2α receptor silencing attenuates vascular remodeling in rats with type 2 diabetes.

BACKGROUND: Vascular remodeling is an important feature of diabetic macrovascular complications. The prostaglandin F2α receptor (FP), the expression of which is upregulated by insulin resistance and diabetes, is reportedly involved in myocardial remodeling. In this study, we aimed to investigate whether the FP receptor is implicated in diabetes-induced vascular remodeling. METHODS: A type 2 diabetic rat model was induced through a high-fat diet and low-dose streptozotocin (STZ). Thirty-two rats were randomized into four groups: control, diabetes, diabetes treated with empty virus and diabetes treated with FP receptor-shRNA. Then, we evaluated the metabolic index, FP receptor expression and vascular remodeling. We used FP receptor gene silencing in vivo to investigate the role that the FP receptor plays in the pathophysiologic features of vascular remodeling. RESULTS: Diabetic rats displayed increased levels of blood glucose, cholesterol, and triglycerides, as well as severe insulin resistance and FP receptor overexpression. In addition, increased medial thickness, excessive collagen deposition and diminished elastic fibers were observed in the diabetic rats, resulting in vascular remodeling. In the FP receptor-shRNA group, the medial thickness, collagen content, elastin/collagen ratio, and collagen I/collagen III content ratio were markedly decreased. Additionally, with FP receptor gene silencing, the JNK phosphorylation level was markedly decreased. CONCLUSIONS: Silencing of the FP receptor exerts a protective effect on diabetes-induced vascular remodeling, thereby suggesting a new therapeutic target for vascular remodeling in diabetes.

Female Type 1 Diabetic Akita Mice Demonstrate Increased Bladder Contractility via FP Receptor Activation due to NLRP3-Mediated Inflammation.

BACKGROUND: Diabetic bladder dysfunction (DBD) is driven in part by inflammation which dysregulates prostaglandin release in the bladder. Precise inflammatory mechanisms responsible for such dysregulation have been elusive. Since prostaglandins impact bladder contractility, elucidating these mechanisms may yield potential therapeutic targets for DBD. In female Type 1 diabetic Akita mice, inflammation mediated by the nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-3 (NLRP3) inflammasome is responsible for DBD. Here, we utilized female Akita mice crossbred with NLRP3 knock-out mice to determine how NLRP3-driven inflammation impacts prostaglandin release within the bladder and prostaglandin-mediated bladder contractions. METHODS: Akita mice were crossbred with NLRP3-⁣/- mice to yield four groups of non-diabetics and diabetics with and without the NLRP3 gene. Females were aged to 30 weeks when Akitas typically exhibit DBD. Urothelia and detrusors were stretched ex vivo to release prostaglandins. Prostaglandin E2 (PGE2) and prostaglandin F2α (PGF2α) were quantified using enzyme linked immunosorbent assays (ELISA). In separate samples, ex vivo contractile force to PGE2 and PGF2α +/- the prostaglandin F (FP) receptor antagonist, AL8810, was measured. FP receptor protein expression was determined via western blotting. RESULTS: Stretch-induced PGE2 release increases in urothelia but decreases in detrusors of diabetics. However, PGE2-mediated bladder contractions are not impacted. Conversely, diabetics show no changes in PGF2α release, but PGF2α-mediated contractions increase significantly. This is likely due to signaling through the FP receptors as FP receptor antagonism prevents this increase and diabetics demonstrate a four-fold increase in FP receptor proteins. Without NLRP3-mediated inflammation, changes in prostaglandin release, contractility, and receptor expression do not occur. CONCLUSION: NLRP3-dependent inflammation dysregulates prostaglandin release and prostaglandin-mediated bladder contractions in diabetic female Akita mice via FP receptor upregulation.

Prostaglandin FP receptor agonists in the treatment of glaucoma and ocular hypertension: a literature review.

INTRODUCTION: Glaucoma is a leading cause of blindness with intraocular pressure (IOP) as the only known modifiable risk factor. Prostaglandin FP receptor agonists are the first-line medical treatment for glaucoma and ocular hypertension. Despite their efficacy, their IOP lowering effect may be insufficient requiring second agents, and poor patient compliance to medical therapy may preclude their full effect. AREAS COVERED: This literature review examines the novel FP receptor drugs and drug delivery devices in clinical phase trials for treatment of glaucoma. Three novel drugs targeting FP receptors were identified, including latanoprostene bunod, NCX 470, and sepetaprost. Additionally, sustained drug delivery devices in early clinical phase trials included intracameral implants, punctal plugs, ocular rings, and contact lenses. EXPERT OPINION: NO hybrid FP receptor agonists and dual FP/EP3 receptor agonists may show promise as novel medical therapies with greater efficacy than approved prostaglandin analogs in clinical use, with a similar safety profile. Alternatively, drug delivery systems may provide a similar IOP lowering effect to existing agonists but overcome issues with patient compliance and convenience. A personalized approach to drug delivery devices may be required to ensure the most appropriate fit for the patient according to the invasiveness and duration of therapy desired.

Persistence of the carteolol hydrochloride/latanoprost fixed-combination ophthalmic solution, compared with the other ß-blocker/prostanoid FP receptor agonist fixed-combination ophthalmic solutions.

PURPOSE: To investigate the treatment persistence of carteolol hydrochloride/latanoprost fixed-combination ophthalmic solution (CAR/LAT) and other ß-blocker/prostanoid FP receptor agonist fixed-combination ophthalmic solutions (BB/FP) in the treatment of glaucoma. STUDY DESIGN: Retrospective observational cohort study. METHODS: A retrospective observational cohort study using JMDC Claims Database. Patients aged 20 years or older diagnosed with glaucoma between February 1, 2017, and March 31, 2020, and prescribed CAR/LAT or another BB/FP were included. RESULTS: A total of 16,612 patients (7423 in the CAR/LAT group and 9189 in the other BB/FP group) were included. The cumulative treatment persistence rate at the end of follow-up was 42.0% (64.9% at 1 year, 53.4% at 2 years, 45.0% at 3 years, and 42.0% at 4 years) in the CAR/LAT group and 34.7% (54.8% at 1 year, 43.6% at 2 years, 37.1% at 3 years, and 34.7% at 4 years) in the other BB/FP group. Treatment persistence was significantly longer in the CAR/LAT group compared to that in the other BB/FP group (hazard ratio 0.747, p < 0.0001). Over the treatment period, the number of patients who discontinued treatment was 3281 (44.2%) in the CAR/LAT group and 4926 (53.6%) in the other BB/FP group; the median duration of treatment was 135 days and 97 days, respectively. CONCLUSION: The study results suggest that persistence rates vary depending on the BB/FP and CAR/LAT appears to be more persistent than other BB/FP.

PGF2α induces a pro-labour phenotypical switch in human myometrial cells that can be inhibited with PGF2α receptor antagonists.

Preterm birth is the leading cause of infant morbidity and mortality. There has been an interest in developing prostaglandin F2α (PGF2α) antagonists as a new treatment for preterm birth, although much of the rationale for their use is based on studies in rodents where PGF2α initiates labour by regressing the corpus luteum and reducing systemic progesterone concentrations. How PGF2α antagonism would act in humans who do not have a fall in systemic progesterone remains unclear. One possibility, in addition to an acute stimulation of contractions, is a direct alteration of the myometrial smooth muscle cell state towards a pro-labour phenotype. In this study, we developed an immortalised myometrial cell line, MYLA, derived from myometrial tissue obtained from a pregnant, non-labouring patient, as well as a novel class of PGF2α receptor (FP) antagonist. We verified the functionality of the cell line by stimulation with PGF2α, resulting in Gαq-specific coupling and Ca2+ release, which were inhibited by FP antagonism. Compared to four published FP receptor antagonists, the novel FP antagonist N582707 was the most potent compound [Fmax 7.67 ± 0.63 (IC50 21.26 nM), AUC 7.30 ± 0.32 (IC50 50.43 nM), and frequency of Ca2+ oscillations 7.66 ± 0.41 (IC50 22.15 nM)]. RNA-sequencing of the MYLA cell line at 1, 3, 6, 12, 24, and 48 h post PGF2α treatment revealed a transforming phenotype from a fibroblastic to smooth muscle mRNA profile. PGF2α treatment increased the expression of MYLK, CALD1, and CNN1 as well as the pro-labour genes OXTR, IL6, and IL11, which were inhibited by FP antagonism. Concomitant with the inhibition of a smooth muscle, pro-labour transition, FP antagonism increased the expression of the fibroblast marker genes DCN, FBLN1, and PDGFRA. Our findings suggest that in addition to the well-described acute contractile effect, PGF2α transforms myometrial smooth muscle cells from a myofibroblast to a smooth muscle, pro-labour-like state and that the novel compound N582707 has the potential for prophylactic use in preterm labour management beyond its use as an acute tocolytic drug.

Prostaglandin-Associated Periorbitopathy Symptom Alleviation After Switching Prostaglandin F Receptor Agonist to EP2 Receptor Agonist in Patients with Glaucoma.

Purpose: Prostaglandin-associated periorbitopathy in patients with glaucoma is reportedly not caused by EP2 agonist, but it has been a cosmetic problem with prostaglandin F receptor (FP) agonists. In this study, patients with prostaglandin-associated periorbitopathy on FP agonists were switched to EP2 agonist and changes were investigated. Methods: Patients complaining of prostaglandin-associated periorbitopathy were included. The FP agonist was switched to EP2 agonist (omidenepag isopropyl), and patients were followed up for 7 months. Frontal photographs were taken at every visit, and objective changes in deepening of the upper eyelid sulcus were assessed by three observers. Subjective questionnaires (self-awareness of deepening of the upper eyelid sulcus, eyelid/peri-eyelid skin pigmentation, eyelash elongation, and conjunctival hyperemia) were acquired at the start and the endpoint. Factors associated with the change of prostaglandin-associated periorbitopathy were investigated using logistic regression analysis. Results: Included were 23 eyes of 23 patients (17 women; 60.6 years). At 7 months, objective deepening of the upper eyelid sulcus improved by 76%. The subjective questionnaires showed that deepening of the upper eyelid sulcus improved in 95%, eyelid/peri-eyelid skin pigmentation in 76%. The less extent of myopia was a significant factor in the eyes with improved eyelid/peri-eyelid skin pigmentation. After switching, no change in intraocular pressure or visual acuity was observed (P ≥ 0.22). Conclusion: Switching to omidenepag isopropyl increased patient satisfaction and might be the first step to lightening deepening of the upper eyelid sulcus and eyelid/peri-eyelid skin pigmentation. It was suggested that pigmentation may be more easily improved in nonmyopic eyes.

Newly or switching effect of a selective EP2 agonist on intraocular pressure in Japanese patients with open-angle glaucoma.

PURPOSE: To evaluate omidenepag isopropyl (OMDI) for its efficacy in intraocular pressure control (IOP) and adverse reactions following administrations in Japanese patients with open-angle glaucoma (OAG) over a 3-month period. STUDY DESIGN: Retrospective observational study. SUBJECTS AND METHODS: Group 1 included untreated OAG patients, Group 2 included OAG patients treated with prostaglandin F (FP) receptor agonists (monotherapy) and Group 3 included OAG patients treated with multidrug therapy, including FP receptor agonists. OMDI was newly administered in Group 1, and FP receptor agonists were switched to OMDI in Group 2. In Group 3, all other ocular hypotensive medications were continued except FP receptor agonists. IOP changes were examined, and adverse reactions were retrieved from the medical records. RESULTS: Group 1 included 32 eyes, Group 2, 20 eyes and Group 3, 17 eyes. In Group 1, the baseline IOP was 15.7 mmHg (95% confidence interval [CI] 14.7-16.8 mmHg). After eyedrop treatment, the IOP was 14.1 mmHg (P < 0.001) at 1 month and 13.7 mmHg (P < 0.001) at 3 months. By contrast, in Group 2 and Group 3, switching FP receptor agonists to OMDI did not result in significant IOP changes (P ≥ 0.71). Six patients developed adverse reactions (hyperemia, headache, ocular pain, and swollen eyelids). CONCLUSIONS: New administration of OMDI significantly reduced the IOP. Furthermore, the IOP did not change after switching from FP receptor agonists to OMDI, including multidrug therapy. OMDI can be used as a first-line drug and is comparable to FP receptor agonists in Japanese patients with OAG.

PGE2 vs PGF2α in human parturition.

Prostaglandin E2 (PGE2) and F2α (PGF2α) are the two most prominent prostanoids in parturition. They are involved in cervical ripening, membrane rupture, myometrial contraction and inflammation in gestational tissues. Because multiple receptor subtypes for PGE2 and PGF2α exist, coupled with diverse signaling pathways, the effects of PGE2 and PGF2α depend largely on the spatial and temporal expression of these receptors in intrauterine tissues. It appears that PGE2 and PGF2α play different roles in parturition. PGE2 is probably more important for labor onset, while PGF2α may play a more important role in labor accomplishment, which may be attributed to the differential effects of PGE2 and PGF2α in gestational tissues. PGE2 is more powerful than PGF2α in the induction of cervical ripening. In terms of myometrial contraction, PGE2 produces a biphasic effect with an initial contraction and a following relaxation, while PGF2α consistently stimulates myometrial contraction. In the fetal membranes, both PGE2 and PGF2α appear to be involved in the process of membrane rupture. In addition, PGE2 and PGF2α may also participate in the inflammatory process of intrauterine tissues at parturition by stimulating not only neutrophil influx and cytokine production but also cyclooxygenase-2 expression thereby intensifying their own production. This review summarizes the differential roles of PGE2 and PGF2α in parturition with respect to their production and expression of receptor subtypes in gestational tissues. Dissecting the specific mechanisms underlying the effects of PGE2 and PGF2α in parturition may assist in developing specific therapeutic targets for preterm and post-term birth.

Prostanoid receptor agonists for glaucoma treatment.

Intraocular pressure reduction is the only available and evidence-based medical therapy for glaucoma. Currently, the first-line eye drops are prostaglandin analogues including latanoprost, travoprost, bimatoprost, and tafluprost. These drugs stimulate intraocular prostanoid false positive (FP) receptors and reduce intraocular pressure by increasing mainly uveoscleral aqueous outflow. For 2 decades since latanoprost was launched, no drug has been comparable in its efficacy. In 2018, a prostanoid EP2 agonist, omidenepag, was launched in Japan. Current FP agonists and EP2 agonists indicate comparable intraocular pressure reduction by stimulating prostanoid FP or EP2 receptors. However, their safety profiles are quite different because of the differences between the intracellular signaling pathways through their own receptors. Including these commercially available FP and EP2 receptor agonists, prostanoid receptors have a large potential to control intraocular pressure. In this review I will trace the history and development of FP and EP2 receptor agonists from their original function, and explain their potential as first-line drugs including elucidation of their efficacy and safety.

The Additive Effect of ROCK Inhibitor on Prostaglandin-Treated Japanese Patients with Glaucoma Indicating 15 mmHg and Under: ROCK U-15.

INTRODUCTION: We aimed to evaluate the additional effects and safety of a Rho-associated protein kinase (ROCK) inhibitor, ripasudil hydrochloride hydrate, in Japanese patients with primary open-angle glaucoma (POAG) with an intraocular pressure (IOP) of at most 15 mmHg undergoing prostaglandin F2α (FP) receptor agonist monotherapy (FP monotherapy). METHODS: In this prospective observational study, 30 Japanese patients with POAG and IOP of at most 15 mmHg (mean age 59.4 years; 10 men) who were undergoing FP monotherapy in both eyes were administered an additional dose of ripasudil hydrochloride hydrate (GLANATEC ophthalmic solution 0.4%: ripasudil) in one eye. The following factors were investigated at 1 and 3 months after the initiation of ripasudil treatment: (1) magnitude of change in IOP between the treated and contralateral untreated eyes, (2) number of treated eyes showing 20% and 30% IOP reduction, (3) IOP difference between treated and contralateral untreated eyes, and (4) safety during the treatment period. Both (1) and (3) were analyzed using the mixed-effect model for repeated measurements. RESULTS: The treated eyes showed significant reduction in IOP at 1 month (- 1.92 mmHg, P < 0.001) and 3 months (- 1.81 mmHg, P < 0.001). In contrast, contralateral untreated eyes did not show IOP reduction at 1 month (0.53 mmHg, P = 0.016) and 3 months (0.38 mmHg, P = 0.15). IOP reduction of - 20% and - 30% was achieved in 9 (30%) and 3 (10%) treated eyes, respectively. There were significant differences in IOP between the treated and contralateral untreated eyes at 1 month (- 2.46 mmHg, P < 0.001) and 3 months (- 2.20 mmHg, P < 0.001). Two patients experienced local adverse events (facial edema, one patient at week 1; blepharitis, one patient at 1 month); they recovered quickly after stopping ripasudil administration. CONCLUSION: In patients with POAG with an IOP of at most 15 mmHg undergoing FP monotherapy, the addition of ripasudil resulted in significant IOP lowering at 1 and 3 months. Ripasudil could be used to enhance the outcome of FP monotherapy. TRIAL REGISTRATION: Registered UMIN ID: UMIN000030742.

Recovery of deepening of the upper eyelid sulcus after switching from prostaglandin FP receptor agonists to EP2 receptor agonist: a 3-month prospective analysis.

PURPOSE: To examine the effect of switching from a prostanoid FP receptor agonists to EP2 receptor agonist (omidenepag isopropyl) on the deepening of the upper eyelid sulcus (DUES) and intraocular pressure (IOP) in Japanese glaucoma patients over 3 months post treatment. STUDY DESIGN: Prospective observational study. METHODS: Patients with glaucoma who received FP receptor agonists treatment and had complained of DUES-related reduction in quality of life were included. Their FP receptor agonists was switched to omidenepag isopropyl without a drug holiday. At baseline and 1 and 3 months post-switch, photographs were taken and the changes in DUES were assessed by three independent observers. IOP and adverse events were also assessed. RESULTS: The study included 23 eyes of 23 patients (6 men, 17 women; average age, 60.6 years). After switching, DUES improved in 12 eyes at 1 month and in 16 eyes at 3 months; eyes in the remaining patients showed no worsening of the condition. The mean IOP before switching was 15.3 ± 3.3 mmHg (95% confidence interval 13.9-16.7 mmHg). Following the switch, the mean IOP values were 15.6 ± 3.3 mmHg (14.1-17.0 mmHg) at 1 month and 15.5 ± 3.3 mmHg (14.1-16.9 mmHg) at 3 months (P = 1.0 at 1 month, P = 1.0 at 3 months; both adjusted by Bonferroni correction). No adverse effects were observed. CONCLUSION: Omidenepag isopropyl improved DUES while maintaining IOP in over 70% of Japanese patients with glaucoma who exhibited DUES caused by FP receptor agonists; the improvement was observed within 3 months after switching from FP receptor agonists.

Prostaglandin D2 evokes potent uterine contraction via the F prostanoid receptor in postpartum rats.

Prostaglandin (PG) D2, a prostanoid known to have hypotensive effect, can evoke increased in vitro prepartum myometrial contraction resulting from up-regulation of the F prostanoid (FP) receptor. The present study further determined postpartum rat uterine responses to PGD2 to evaluate the possibility of the prostanoid becoming a therapeutic for postpartum uterine atony, a major cause of postpartum hemorrhage that can lead to maternal morbidity. In vitro and in vivo postpartum uterine responses to PGD2 were determined and compared to those of prepartum rats. Here we show that in postpartum myometrial strips PGD2 did evoke a contraction sensitive to FP receptor antagonism. Interestingly, this response was not only to a greater extent than that of prepartum rats, but also comparable with the contraction obtained with PGF2α, a therapeutic for postpartum uterine atony but contradicted in conditions including hypertension. Indeed, PGD2 was also found to cause increases of basal uterine contraction under in vivo conditions. Western blots revealed that the expression of FP receptors in postpartum myometrium was higher than that of prepartum rats. Moreover, we noted that the amount of PGD2 produced in postpartum uteri, although lower than that of prepartum rats, was increased compared to non-pregnant conditions. These results thus demonstrate that due to a further up-regulation or high expression of myometrial FP receptors, PGD2 can evoke potent uterine contraction postpartum, and hence the prostanoid, which is naturally synthesized in uterine tissues, could be a potential therapeutic for postpartum uterine atony, especially in settings, such as hypertension.

Influence of omega-3 polyunsaturated fatty acids from fish oil or meal on the structure of lipid microdomains in bovine luteal cells.

Biological membranes are composed of a lipid bilayer and proteins that form lipid microdomains. This study examined the effects of fish byproducts on lipid-protein interactions within lipid microdomains of bovine luteal cells. In Exp. 1 and 2, luteal cells were prepared from corpora lutea (CL; n = 4 to 8) collected at an abattoir. Exp. 1 was conducted to optimize ultrasonication in a detergent-free protocol for isolation of lipid microdomains. A power setting of 10 to 20% was effective in isolating lipid microdomains from bulk lipid. In Exp. 2, cells were cultured in control medium or fish oil to determine influence of fish oil on distribution of lipid microdomain markers and prostaglandin F2α (FP) receptors. Cells treated with fish oil had a smaller percentage of microdomain markers and FP receptor in microdomains (P < 0.05). In Exp. 3 and 4, cells were prepared from mid-cycle CL obtained from cows supplemented with corn gluten meal (n = 4) or fish meal (n = 4). Exp. 3 examined effects of dietary supplementation on distribution of lipid microdomain markers and FP receptor and Exp. 4 on fatty acid composition within lipid microdomains. A smaller percentage of lipid microdomain markers and FP receptor was detected in microdomains of cells collected from fish meal supplemented animals (P < 0.05). In Exp. 4, a greater percentage of omega-3 polyunsaturated fatty acids was detected in bulk lipid from fish meal supplemented cows (P < 0.05). Results show that fish byproducts influence lipid-protein interactions in lipid microdomains in bovine luteal cells.

Confirmation of the Cardiac Safety of PGF2α Receptor Antagonist OBE022 in a First-in-Human Study in Healthy Subjects, Using Intensive ECG Assessments.

OBE022, a new orally active prostaglandin F2α  receptor antagonist (OBE022) with myometrial selectivity is being developed to reduce uterine contractions during preterm labor. This first-in-human study evaluated the effect of OBE022 following multiple doses on the QT interval in 23 healthy postmenopausal women, using the effect of a meal on QTc to demonstrate assay sensitivity. We report the cardiac safety outcome performed during the multiple ascending part of this trial. OBE022 was administered after a standardized breakfast on day 1 and in the fasted state from day 3 to day 9 wth a standardized lunch 4 hours after administration. Concentration-effect modeling was used to assess the effect of prodrug OBE022 and parent OBE002 on QTc after a single dose (days 1 and 3) and multiple doses (day 9). The concentration-response analysis showed the absence of QTc prolongation at all doses tested. Two-sided 90% confidence intervals of the geometric mean Cmax  for estimated QTc effects of OBE022 and OBE002 of all dose groups were consistently below the threshold of regulatory concern. The sensitivity of this study to detect small changes in the QTc was confirmed by a significant shortening of the QTc on days 1, 3, and 9 after standardized meals. This study establishes that neither prodrug OBE022 nor parent OBE002 prolong the QTc interval. The observed food effect on the QT interval validated the assay on all assessment days. Both the change from predose, premeal and the change from premeal, postdose demonstrated the specificity of the method.

Investigational drugs targeting prostaglandin receptors for the treatment of glaucoma.

INTRODUCTION: Prostaglandin F2α analogs were the first prostaglandin agonists introduced for glaucoma treatment. Thanks to their efficacy and favorable tolerability they set a high bar in competition, with a resultant paucity in new hypotensive drug development for many years. However, the scientific community has shown recently a new interest in exploring new options for glaucoma treatment, generating a remarkable incentive in the marketplace for new drugs. AREAS COVERED: This article reviews agents targeting prostaglandin receptors that are currently being investigated for glaucoma treatment. We searched published literature for agonists targeting all subtypes of prostaglandin receptors found in ocular tissues. EP and FP receptor agonists are currently in the spotlight of clinical research, while less attention is paid in DP receptor agonists. EXPERT OPINION: Prostaglandin analogs, targeting different and combinations of receptor subtypes and compounds that exhibit additivity to commonly prescribed medications seem to be highly promising options. New treatments need to be safe, more effective, superior to existing therapies, tolerable and cost-effective. New generation compounds with multiple mechanisms of action or multiagent formulations are vigorously being investigated and generated in laboratories around the world.