Characteristics of inner-city children with asthma: the National Cooperative Inner-City Asthma Study

Asthma morbidity has increased dramatically in the past decade, especially among poor and minority children in the inner cities. The National Cooperative Inner-City Asthma Study (NCICAS) is a multicenter study designed to determine factors that contribute to asthma morbidity in children in the inner cities. A total of 1,528 children with asthma, ages 4 to 9 years old, were enrolled in a broad-based epidemiologic investigation of factors which were thought to be related to asthma morbidity. Baseline assessment included morbidity, allergy evaluation, adherence and access to care, home visits, and pulmonary function. Interval assessments were conducted at 3, 6, and 9 months after the baseline evaluations. Over the one-year period, 83% of the children had no hospitalizations and 3.6% had two or more. The children averaged 3 to 3.5 days of wheeze for each of the four two-week recall periods. The pattern of skin test sensitivity differed from other populations in that positive reactions to cockroach were higher (35%) and positive reactions to house dust mite were lower (31%). Caretakers reported smoking in 39% of households of children with asthma, and cotinine/creatinine ratios exceeded 30 ng/mg in 48% of the sample. High exposure (> 40 ppb) to nitrogen dioxide was found in 24% of homes. Although the majority of children had insurance coverage, 53% of study participants found it difficult to get follow-up asthma care. The data demonstrate that symptoms are frequent but do not result in hospitalization in the majority of children. These data indicate a number of areas which are potential contributors to the asthma morbidity in this population, such as environmental factors, lack of access to care, and adherence to treatment. Interventions to reduce asthma morbidity are more likely to be successful if they address the many different asthma risks found in the inner cities.

A randomized clinical trial to reduce asthma morbidity among inner-city children: results of the National Cooperative Inner-City Asthma Study

OBJECTIVE

To evaluate a family-focused asthma intervention designed for inner-city children 5 to 11 years old with moderate to severe asthma.

STUDY DESIGN

Randomized, multisite, controlled trial to minimize symptom days (wheeze, loss of sleep, reduction in play activity) measured by a 2-week recall assessed at 2-month intervals over a 2-year follow-up period. The intervention was tailored to each family's individual asthma risk profile assessed at baseline.

RESULTS

Averaged over the first 12 months, participants in the intervention group (n = 515) reported 3.51 symptom days in the 2 weeks before each follow-up interview compared with 4.06 symptom days for the control group (n = 518), a difference of 0.55 (95% CI, 0.18 to 0.92, P =.004). The reduction among children with severe asthma was approximately 3 times greater (1.54 d/2 wk). More children in the control group (18.9%) were hospitalized during the intervention compared with children in the intervention group (14. 8%), a decrease of 4.19% (CI, -8.75 to 0.36, P =.071). These improvements were maintained in the intervention group during the second year of follow-up, during which they did not have access to the asthma counselor.

CONCLUSIONS

We demonstrated that an individually tailored, multifaceted intervention carried out by Masters-level social workers trained in asthma management can reduce asthma symptoms among children in the inner city.

Apixaban, an oral, direct and highly selective factor Xa inhibitor: in vitro, antithrombotic and antihemostatic studies

BACKGROUND

Apixaban is an oral, direct and highly selective factor Xa (FXa) inhibitor in late-stage clinical development for the prevention and treatment of thromboembolic diseases.

OBJECTIVE

We evaluated the in vitro properties of apixaban and its in vivo activities in rabbit models of thrombosis and hemostasis.

METHODS

Studies were conducted in arteriovenous-shunt thrombosis (AVST), venous thrombosis (VT), electrically mediated carotid arterial thrombosis (ECAT) and cuticle bleeding time (BT) models.

RESULTS

In vitro, apixaban is potent and selective, with a K(i) of 0.08 nm for human FXa. It exhibited species difference in FXa inhibition [FXa K(i) (nm): 0.16, rabbit; 1.3, rat; 1.7, dog] and anticoagulation [EC(2x) (microm, concentration required to double the prothrombin time): 3.6, human; 2.3, rabbit; 7.9, rat; 6.7, dog]. Apixaban at 10 microm did not alter human and rabbit platelet aggregation to ADP, gamma-thrombin, and collagen. In vivo, the values for antithrombotic ED(50) (dose that reduced thrombus weight or increased blood flow by 50% of the control) in AVST, VT and ECAT and the values for BT ED(3x) (dose that increased BT by 3-fold) were 0.27 +/- 0.03, 0.11 +/- 0.03, 0.07 +/- 0.02 and > 3 mg kg(-1) h(-1) i.v. for apixaban, 0.05 +/- 0.01, 0.05 +/- 0.01, 0.27 +/- 0.08 and > 3 mg kg(-1) h(-1) i.v. for the indirect FXa inhibitor fondaparinux, and 0.53 +/- 0.04, 0.27 +/- 0.01, 0.08 +/- 0.01 and 0.70 +/- 0.07 mg kg(-1) day(-1) p.o. for the oral anticoagulant warfarin, respectively.

CONCLUSIONS

In summary, apixaban was effective in the prevention of experimental thrombosis at doses that preserve hemostasis in rabbits.

Psychosocial characteristics of inner-city children with asthma: a description of the NCICAS psychosocial protocol. National Cooperative Inner-City Asthma Study

Previous research has demonstrated a significant reciprocal relationship between psychosocial factors and asthma morbidity in children. The National Cooperative Inner-City Asthma Study investigated both asthma-specific and non-specific psychosocial variables, including asthma knowledge beliefs and management behavior, caregiver and child adjustment, life stress, and social support. This article presents these psychosocial characteristics in 1,528 4-9-year-old asthmatic urban children and their caretakers. Caretakers demonstrated considerable asthma knowledge, averaging 84% correct responses on the Asthma Information Quiz. However, respondents provided less than one helpful response for each hypothetical problem situation involving asthma care, and most respondents had more than one undesirable response, indicating a potentially dangerous or maladaptive action. Both adults and children reported multiple caretakers responsible for asthma management (adult report: average 3.4, including the child); in addition, children rated their responsibility for self-care significantly higher than did adults. Scores on the Child Behavior Checklist indicated increased problems compared to normative samples (57.3 vs. 50, respectively), and 35% of children met the criteria for problems of clinical severity. On the Brief Symptom Inventory, adults reported elevated levels of psychological distress (56.02 vs norm of 50); 50% of caretakers had symptoms of clinical severity. Caretakers also experienced an average of 8.13 undesirable life events in the 12 months preceding the baseline interview. These findings suggest that limited asthma problem-solving skills, multiple asthma managers, child and adult adjustment problems, and high levels of life stress are significant concerns for this group and may place the inner-city children in this study population at increased risk for problems related to adherence to asthma management regimens and for asthma morbidity.

Patient-provider communication during the emergency department care of children with asthma. The National Cooperative Inner-City Asthma Study, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD

OBJECTIVES

Poor children's reliance on emergency facilities is one factor implicated in the rise of morbidity attributed to asthma. Although studies have examined doctor-patient communication during routine pediatric visits, little data are available about communication during emergency care. This study sought to describe communication during emergency treatment of childhood asthma to learn if a "patient-centered" provider style was associated with increased parent satisfaction and increased parent and child participation.

METHODS

This cross-sectional, observational study examined 104 children aged 4 to 9 years and their guardian(s) attending emergency departments in seven cities. Quantitative analysis of provider-family dialogue was performed. Questionnaires measured satisfaction with care, provider informativeness, and partnership.

RESULTS

Providers' talk to children was largely supportive and directive; parents received most counseling and information. Children spoke little to providers (mean: 20 statements per visit versus 156 by parents). Providers made few statements about psychosocial aspects of asthma care (mean: three per visit). Providers' patient-centered style with parents was associated with more talk from parents and higher ratings for informativeness and partnership. Patient-centered style with children was associated with five times the amount of talk from children and with higher parent ratings for "good care," but not for informativeness or partnership.

CONCLUSIONS

Communication during emergency asthma care was overwhelmingly biomedical. Children took little part in discussions. A patient-centered style correlated with increased parent and child participation, but required directing conversation toward both parents and children.

Design and methods of the National Cooperative Inner-City Asthma Study

The National Cooperative Inner-City Asthma Study (NCICAS) was established to identify and then intervene on those factors which are related to asthma morbidity among children in the inner-city. This paper describes the design and methods of the broad-based initial Phase I epidemiologic investigation. Eight research centers enrolled 1,528 children, 4 to 9 years of age, from English- or Spanish-speaking families, all of whom resided in major metropolitan inner-city areas. The protocol included an eligibility assessment and an extensive baseline visit, during which symptom data, such as wheezing, lost sleep, changes in activities of daily living, inpatient admissions, and emergency department and clinic visits were collected. A comprehensive medical history for each child was taken and adherence to the medical regimen was assessed. Access, as well as barriers, to the medical system were addressed by a series of questions including the location, availability, and consistency of treatment for asthma attacks, follow-up care, and primary care. The psychological health of the caretaker and of the child was also measured. Asthma knowledge of the child and caretaker was determined. Sensitization to allergens was assessed by skin-prick allergen testing and exposure to cigarette smoke and the home environment were assessed by questionnaire. For more than a third of the families, in-home visits were conducted with dust sample allergen collection and documentation of the home environment, such as the presence of pets and evidence of smoking, mildew, and roaches. Urine specimens were collected to measure passive smoke exposure by cotinine assays, blood samples were drawn for banking, and children age 6 to 9 years were given spirometric lung function assessment. At 3, 6 and 9 months following the baseline assessment, telephone interviews were conducted to ask about the child's symptoms, unscheduled emergency department or clinic visits, and hospitalizations. At this time, peak flow measurements with 2-week diary symptom records were collected.

Self-reported adherence, management behavior, and barriers to care after an emergency department visit by inner city children with asthma

OBJECTIVE

The inability to adhere to a prescribed therapeutic program for the treatment of a chronic disease may be responsible in part for continued disease activity. This problem may be more of an issue in the treatment of asthma, a common, potentially lethal chronic condition in which the lack of symptoms may be interpreted as remission. Adherence was one of the key areas of interest for the National Cooperative Inner-City Asthma Study. The focus of this study was to identify those issues reported by families that could adversely affect their adherence to an asthma care program. The identification of barriers to adherence could then form the basis of a successful intervention program. This study describes barriers to adherence, asthma management behavior, and self-reported adherence.

METHODS

Patients presenting during an acute attack of asthma at an emergency department (ED) were recruited for this study. The medical record of the ED encounter was abstracted and compared with information that was obtained during a baseline interview 3 to 5 weeks later. During the baseline interview, parents were asked about health care behaviors related to adherence.

RESULTS

There were 344 children 4 to 9 years of age living in inner city census tracts in the study. Four areas of adherence (medicine use, appointment-keeping, emergency actions, and asthma attack prevention) were investigated. The parental report of medications prescribed at the ED and the information on the abstracted ED report agreed 94.9% of the time for the beta-agonists, 86.8% for steroids, and 69.4% for cromolyn. Among respondents, 85.4% of parents reported that they are able to follow the ED recommendations almost all of the time; side effects of medicines were a concern for 81.1% of caretakers who were adherent and for 89.5% of caretakers who were nonadherent. Doubts regarding the usefulness of medications occurred in 34.4% of those considered adherent and 54.2% who admitted nonadherence. Medications were forgotten some of the time by 45.2% of the children, and 52.8% tried to get out of taking medicine. Appointments for follow-up care were kept by 69% of those given an appointment in the ED, by an estimated 60.0% of those who were told specifically to call for an appointment, and by an estimated 25.2% of those who were neither given an appointment nor told specifically to make one. Only one third of parents report that they were able to keep the child away from known asthma triggers nearly all of the time. Approximately half avoided allergens; however, only 37.5% reported avoidance of cigarette smoke. The use of preventive medicines occurred in 23.5%. Using a medicine and taking the child to a physician were reported as the first or second action during an acute attack of asthma by 72.1% of respondents.

CONCLUSIONS

Adherence to an asthma-management program involves a number of areas: medication, appointment-keeping, prevention, and applying an emergency plan of action. Barriers to adherence may exist in one or all four of these areas, leading to ineffective control of asthma. Recommendations are made for improving the patient-physician partnership to improve adherence.

Favorable therapeutic index of the direct factor Xa inhibitors, apixaban and rivaroxaban, compared with the thrombin inhibitor dabigatran in rabbits

BACKGROUND

Apixaban is an oral, direct factor Xa (FXa) inhibitor in late-stage clinical development. This study assessed effects of the direct FXa inhibitors, apixaban and rivaroxaban, vs. the direct thrombin inhibitor, dabigatran, on venous thrombosis (VT), bleeding time (BT) and clotting times in rabbits.

METHODS

We induced the formation of non-occlusive thrombus in VT models by placing threads in the vena cava, and induced bleeding by the incision of cuticles in anesthetized rabbits. Apixaban, rivaroxaban and dabigatran were infused IV to achieve a stable plasma level. Clotting times, including the activated partial thromboplastin time (aPTT), prothrombin time (PT), modified PT (mPT) and thrombin time (TT), were measured.

RESULTS

Apixaban, rivaroxaban and dabigatran exhibited dose-related efficacy in preventing VT with EC(50) of 65, 33 and 194 nm, respectively. At doses for 80% reduction of control thrombus, apixaban, rivaroxaban and dabigatran prolonged BT by 1.13 +/- 0.02-, 1.9 +/- 0.1-* and 4.4 +/- 0.4-fold*, respectively (*P < 0.05, vs. apixaban). In the treatment model, these inhibitors equally prevented growth of a preformed thrombus. Antithrombotic doses of apixaban and rivaroxaban prolonged aPTT and PT by <3-fold with no effect on TT. Dabigatran was > or = 50-fold more potent in prolonging TT than aPTT and PT. Of the clotting assays studied, apixaban, rivaroxaban and dabigatran responded the best to mPT.

CONCLUSION

Comparable antithrombotic efficacy was observed between apixaban, rivaroxaban and dabigatran in the prevention and treatment of VT in rabbits. Apixaban and rivaroxaban exhibited lower BT compared with dabigatran at equivalent antithrombotic doses. The clinical significance of these findings remains to be determined.

Discovery of Milvexian, a High-Affinity, Orally Bioavailable Inhibitor of Factor XIa in Clinical Studies for Antithrombotic Therapy

Factor XIa (FXIa) is an enzyme in the coagulation cascade thought to amplify thrombin generation but has a limited role in hemostasis. From preclinical models and human genetics, an inhibitor of FXIa has the potential to be an antithrombotic agent with superior efficacy and safety. Reversible and irreversible inhibitors of FXIa have demonstrated excellent antithrombotic efficacy without increased bleeding time in animal models (Weitz, J. I., Chan, N. C. Arterioscler. Thromb. Vasc. Biol. 2019, 39 (1), 7-12). Herein, we report the discovery of a novel series of macrocyclic FXIa inhibitors containing a pyrazole P2' moiety. Optimization of the series for (pharmacokinetic) PK properties, free fraction, and solubility resulted in the identification of milvexian (BMS-986177/JNJ-70033093, 17, FXIa Ki = 0.11 nM) as a clinical candidate for the prevention and treatment of thromboembolic disorders, suitable for oral administration.

Nonpeptide factor Xa inhibitors III: effects of DPC423, an orally-active pyrazole antithrombotic agent, on arterial thrombosis in rabbits

DPC423 [1-[3-(aminomethyl)phenyl]-N-[3-fluoro-2'-(methylsulfonyl)[1,1'-biphenyl]-4-yl]-3-(trifluoromethyl)-1H-pyrazole-5-carboxamide] is a synthetic, competitive, and selective inhibitor of coagulation factor Xa (fXa) (K(i): 0.15 nM in humans, 0.3 nM in rabbit). The objective of this study was to compare effects of DPC423, enoxaparin (low-molecular-weight heparin), and argatroban (thrombin inhibitor) on arterial thrombosis and hemostasis in rabbit models of electrically induced carotid artery thrombosis and cuticle bleeding, respectively. Compounds were infused i.v. continuously from 60 min before artery injury or cuticle transection to the end of experiment. Carotid blood flow was used as a marker of antithrombotic effect. Antithrombotic ED(50) values were 0.4 mg/kg/h for enoxaparin (n = 6), 0.13 mg/kg/h for argatroban (n = 6), and 0.6 mg/kg/h for DPC423 (n = 12). DPC423 at the maximum antithrombotic dose increased activated partial thromboplastin time and prothrombin time (n = 6) by 1.8 +/- 0.07- and 1.8 +/- 0.13-fold, respectively, without changes in thrombin time and ex vivo thrombin activity. The antithrombotic effect of DPC423 was significantly correlated with its ex vivo anti-fXa activity (r = 0.86). DPC423 at 1, 3, and 10 mg/kg p.o. increased carotid blood flow (percent control) at 45 min to 10 +/- 4, 24 +/- 6, and 74 +/- 7, respectively (n = 6/group). Cuticle bleeding times (percent change over control) determined at the maximum antithrombotic dose were 88 +/- 12 for argatroban, 69 +/- 13 for heparin, 4 +/- 3 for enoxaparin, 5 +/- 4 for DPC423, and -3 +/- 2 for the vehicle (n = 5-6/group), suggesting dissociation of antithrombotic and bleeding time effects for DPC423 and enoxaparin. The combination of aspirin and DPC423 at ineffective antithrombotic doses produced significant antithrombotic effect. Therefore, these results suggest that DPC423 is a clinically useful oral anticoagulant for the prevention of arterial thrombosis.

Milvexian, an orally bioavailable, small-molecule, reversible, direct inhibitor of factor XIa: In vitro studies and in vivo evaluation in experimental thrombosis in rabbits

BACKGROUND

Milvexian (BMS-986177/JNJ-70033093) is an orally bioavailable factor XIa (FXIa) inhibitor currently in phase 2 clinical trials.

OBJECTIVES

To evaluate in vitro properties and in vivo characteristics of milvexian.

METHODS

In vitro properties of milvexian were evaluated with coagulation and enzyme assays, and in vivo profiles were characterized with rabbit models of electrolytic-induced carotid arterial thrombosis and cuticle bleeding time (BT).

RESULTS

Milvexian is an active-site, reversible inhibitor of human and rabbit FXIa (Ki 0.11 and 0.38 nM, respectively). Milvexian increased activated partial thromboplastin time (APTT) without changing prothrombin time and potently prolonged plasma APTT in humans and rabbits. Milvexian did not alter platelet aggregation to ADP, arachidonic acid, or collagen. Milvexian was evaluated for in vivo prevention and treatment of thrombosis. For prevention, milvexian 0.063 + 0.04, 0.25 + 0.17, and 1 + 0.67 mg/kg+mg/kg/h preserved 32 ± 6*, 54 ± 10*, and 76 ± 5%* of carotid blood flow (CBF) and reduced thrombus weight by 15 ± 10*, 45 ± 2*, and 70 ± 4%*, respectively (*p < .05; n = 6/dose). For treatment, thrombosis was initiated for 15 min and CBF decreased to 40% of control. Seventy-five minutes after milvexian administration, CBF averaged 1 ± 0.3, 39 ± 10, and 66 ± 2%* in groups treated with vehicle and milvexian 0.25 + 0.17 and 1 + 0.67 mg/kg+mg/kg/h, respectively (*p < .05 vs. vehicle; n = 6/group). The combination of milvexian 1 + 0.67 mg/kg+mg/kg/h and aspirin 4 mg/kg/h intravenous did not increase BT versus aspirin monotherapy.

CONCLUSIONS

Milvexian is an effective antithrombotic agent with limited impact on hemostasis, even when combined with aspirin in rabbits. This study supports inhibition of FXIa with milvexian as a promising antithrombotic therapy with a wide therapeutic window.

Arterial antithrombotic and bleeding time effects of apixaban, a direct factor Xa inhibitor, in combination with antiplatelet therapy in rabbits

BACKGROUND

Optimal treatment of arterial thrombosis may include a combination of antiplatelet and anticoagulant drugs. We evaluated apixaban, a direct and highly selective factor Xa inhibitor, in combination with clinically relevant doses of aspirin and/or clopidogrel for prevention of arterial thrombosis in rabbits.

METHODS

Studies were conducted in rabbit models of electrically induced carotid artery thrombosis and cuticle bleeding time (BT). Apixaban 0.04 and 0.3 mg kg(-1) h(-1) or aspirin 1 mg kg(-1) h(-1) was infused intravenous (i.v.) continuously from 1 h before artery injury or cuticle bleed until the end of the experiment. Clopidogrel at 3 mg kg(-1) was dosed orally once daily for three days, with the last dose given 2 h before injury.

RESULTS

Control thrombus weight and BT averaged 8.6 +/- 0.9 mg and 181 +/- 12 s, respectively (n = 6 per group). Effective doses of apixaban that reduced thrombus weight by 20 and 50% (ED(20) and ED(50)) were 0.04 and 0.3 mg kg(-1) h(-1) i.v., respectively. Addition of aspirin to apixaban ED(20) and ED(50) significantly reduced the thrombus weight from 7.4 +/- 0.5 to 5.3 +/- 0.3 and 3.6 +/- 0.3 mg, respectively, with no significant increases in BT (190 +/- 7 s vs.181 +/- 9 and 225 +/- 11 s, respectively). Addition of aspirin and apixaban (ED(20) dose) to clopidogrel produced a further significant reduction in thrombus weight from 5.3 +/- 0.3 to 0.7 +/- 0.1 mg. This combination of clopidogrel and aspirin with apixaban (ED(20) dose) produced a significant but moderate BT increase of 2.1 times control.

CONCLUSIONS

The combination of apixaban and aspirin or apixaban, aspirin and clopidogrel can reduce formation of occlusive arterial thrombosis without excessive increases in BT in rabbits.

Antithrombotic actions of selective inhibitors of blood coagulation factor Xa in rat models of thrombosis

The antithrombotic actions of selective factor Xa (FXa) inhibitors, recombinant tick anticoagulant peptide (rTAP) and DX-9065a, were evaluated in experimental thrombosis models in anesthetized rats. In the first model, thrombosis was induced by exposing flowing blood to a silk thread anchored in an arteriovenous (AV) shunt. rTAP, DX-9065a and heparin, given as an iv infusion 1 hr before blood was circulated in the AV shunt, had ID50s of 0.007, 0.6 mumol/kg/hr and 16 U/kg/hr, respectively. In the model of venous thrombosis which was induced by hypotonic saline (0.225%) followed by 15-min stasis of abdominal vena cava, rTAP and heparin had ID50s of 0.007 mumol/kg/hr and 3.5 U/kg/hr, respectively. In both models, full inhibition of thrombus formation was achieved with FXa inhibition at doses which only modestly increased ex vivo plasma clotting time APTT (1.26 to 1.82 over the baseline). By contrast, the maximum antithrombotic effect of heparin was associated with high and significant APTT prolongation (> 5 fold over the baseline). Therefore, our study suggests that FXa inhibitors are effective agents in preventing thrombosis in both rat thrombosis models and may have therapeutic antithrombotic potential.

Discovery of 4-aryl-7-hydroxyindoline-based P2Y1 antagonists as novel antiplatelet agents

Adenosine diphosphate (ADP)-mediated platelet aggregation is signaled through two distinct G protein-coupled receptors (GPCR) on the platelet surface: P2Y12 and P2Y1. Blocking P2Y12 receptor is a clinically well-validated strategy for antithrombotic therapy. P2Y1 antagonists have been shown to have the potential to provide equivalent antithrombotic efficacy as P2Y12 inhibitors with reduced bleeding in preclinical animal models. We have previously reported the discovery of a potent and orally bioavailable P2Y1 antagonist, 1. This paper describes further optimization of 1 by introducing 4-aryl groups at the hydroxylindoline in two series. In the neutral series, 10q was identified with excellent potency and desirable pharmacokinetic (PK) profile. It also demonstrated similar antithrombotic efficacy with less bleeding compared with the known P2Y12 antagonist prasugrel in rabbit efficacy/bleeding models. In the basic series, 20c (BMS-884775) was discovered with an improved PK and liability profile over 1. These results support P2Y1 antagonism as a promising new antiplatelet target.

The P2Y1 receptor antagonist MRS2500 prevents carotid artery thrombosis in cynomolgus monkeys

Adenosine diphosphate directly induces platelet aggregation via the G-protein coupled P2Y1 and P2Y12 receptors. P2Y12, but not P2Y1, receptor antagonists are available in the clinic. The relevance of the P2Y1 receptor as an antiplatelet target has been studied in rodents, but not in higher species. We therefore examined effects of the pharmacological blockade of the P2Y1 receptor with its selective antagonist MRS2500 in monkey models of electrolytic-mediated arterial thrombosis (ECAT) and kidney bleeding time (KBT). Abciximab, a GPIIb-IIIa antagonist, and cangrelor, a P2Y12 antagonist, were utilized to validate these monkey models. Compounds were given IV at 15-60 min before thrombosis initiation in anesthetized monkeys. Scanning electron microscopy showed the luminal surface of thrombotic artery covered with platelet aggregates and fibrin network. Administration of abciximab at 0.25 and 0.7 mg/kg IV significantly reduced thrombus weight by 71 ± 1 and 100 ± 0 %, and increased KBT by 10.0 ± 0.1- and 10.1 ± 0-fold, respectively (n = 3/dose). Likewise, cangrelor at 0.6 and 2 mg/kg/h IV significantly reduced thrombus weight significantly by 72 ± 9 % and 100 ± 0 % and increased KBT by 2.1 ± 0.1- and 9.8 ± 0.2-fold, respectively (n = 3/dose). MRS2500 [mg/kg + mg/kg/h IV] at 0.09 + 0.14 and 0.45 + 0.68 significantly reduced thrombus weight by 57 ± 1 % and 88 ± 1 % and increased KBT by 2.1 ± 0.3- and 4.9 ± 0.6-fold, respectively (n = 4/dose). In summary, MRS2500 prevented occlusive arterial thrombosis at a dose that moderately prolonged KBT, indicating a role of P2Y1 receptors in arterial thrombosis and hemostasis in monkeys. Thus P2Y1 receptor antagonism provides a suitable target for drug discovery.

Razaxaban, a direct factor Xa inhibitor, in combination with aspirin and/or clopidogrel improves low-dose antithrombotic activity without enhancing bleeding liability in rabbits

Coactivation of platelets and the blood coagulation cascade contributes to the pathophysiology of arterial thrombosis. Combination therapy with antiplatelet and anticoagulant drugs may be needed for maximizing the prevention and treatment of arterial thrombosis. Few studies have thoroughly investigated the combined antithrombotic and bleeding effects of these antithrombotic agents. We, therefore, evaluated the antithrombotic and bleeding profiles of dual and triple therapy with razaxaban, a direct factor Xa inhibitor, plus aspirin and/or clopidogrel in rabbit models of electrolytic injury-induced carotid artery thrombosis and cuticle bleeding time, respectively. Compounds were infused either IV or into the portal vein from 1 h before arterial injury or cuticle transection to the end of experiment. Carotid blood flow was used as a marker of antithrombotic effect. We first evaluated the antithrombotic potency of razaxaban, and examined its ex vivo effects on coagulation parameters to confirm its selectivity. Antithrombotic ED(50) of razaxaban averaged 0.22 +/- 0.05 mg/kg/h (n = 6). Razaxaban at 3 mg/kg/h IV produced full antithrombotic efficacy, increased significantly ex vivo activated partial thromboplastin time and prothrombin time by 2.2 +/- 0.1- and 2.3 +/- 0.1-fold, respectively, and inhibited ex vivo factor Xa activity significantly by 91 +/- 5% (n = 6, P < 0.05) without affecting ex vivo thrombin activity. Razaxaban at concentrations up to 10 muM did not alter in vitro platelet aggregation responses to ADP, gamma-thrombin or collagen. To identify additive or synergistic antithrombotic effects of the various combination therapies, we purposefully used marginally effective doses of razaxaban at 0.1 mg/kg/h, aspirin at 0.3 mg/kg/h and clopidogrel at 1 mg/kg/h. Dual combination of threshold doses of razaxaban and aspirin or clopidogrel produced an enhanced antithrombotic effect without further increases in bleeding time. When compared with dual therapy with aspirin and clopidogrel (38 +/- 5% increase in blood flow), addition of razaxaban increased blood flow to 75 +/- 5% without additional bleeding time effects (n = 6/group, P < 0.05). In summary, razaxaban was an effective antithrombotic agent in a rabbit model of arterial thrombosis. Low-dose razaxaban was useful in combination with sub-optimal doses of aspirin and/or clopidogrel for the prevention of occlusive arterial thrombosis without excessive bleeding.

Discovery of a Potent Parenterally Administered Factor XIa Inhibitor with Hydroxyquinolin-2(1H)-one as the P2' Moiety

Structure-activity relationship optimization of phenylalanine P1' and P2' regions with a phenylimidazole core resulted in a series of potent FXIa inhibitors. Introducing 4-hydroxyquinolin-2-one as the P2' group enhanced FXIa affinity and metabolic stability. Incorporation of an N-methyl piperazine amide group to replace the phenylalanine improved both FXIa potency and aqueous solubility. Combination of the optimization led to the discovery of FXIa inhibitor 13 with a FXIa K i of 0.04 nM and an aPTT EC2x of 1.0 μM. Dose-dependent efficacy (EC50 of 0.53 μM) was achieved in the rabbit ECAT model with minimal bleeding time prolongation.

In Vitro and In Vivo Evaluation of a Small-Molecule APJ (Apelin Receptor) Agonist, BMS-986224, as a Potential Treatment for Heart Failure

Supplemental Digital Content is available in the text.

New heart failure therapies that safely augment cardiac contractility and output are needed. Previous apelin peptide studies have highlighted the potential for APJ (apelin receptor) agonism to enhance cardiac function in heart failure. However, apelin’s short half-life limits its therapeutic utility. Here, we describe the preclinical characterization of a novel, orally bioavailable APJ agonist, BMS-986224.

Discovery of diarylurea P2Y(1) antagonists with improved aqueous solubility

Preclinical data suggests that P2Y1 antagonists, such as diarylurea compound 1, may provide antithrombotic efficacy similar to P2Y12 antagonists and may have the potential of providing reduced bleeding liabilities. This manuscript describes a series of diarylureas bearing solublizing amine side chains as potent P2Y1 antagonists. Among them, compounds 2l and 3h had improved aqueous solubility and maintained antiplatelet activity compared with compound 1. Compound 2l was moderately efficacious in both rat and rabbit thrombosis models and had a moderate prolongation of bleeding time in rats similar to that of compound 1.

Platelet aggregometry and receptor binding to predict the magnitude of antithrombotic and bleeding time effects of clopidogrel in rabbits

Target levels of ex vivo inhibition of platelet aggregation (IPA) induced by adenosine diphosphate (ADP) that produce clinically relevant effects of clopidogrel, a P2Y12 antagonist, are unclear. We examined standard and modified IPA and P2Y12 receptor occupancy as predictors of antithrombotic (% thrombus weight reduction) and bleeding time (BT, fold-increase over control) effects of clopidogrel in rabbit models of carotid artery thrombosis and cuticle bleeding, respectively. Standard and modified IPA with 20 microM ADP were measured in the absence and presence of partial P2Y1 blockade, respectively. Clopidogrel maximally produced standard IPA of 57% +/- 5%, antithrombotic effect of 85% +/- 1%, BT increase of 6.0 +/- 0.4-fold and P2Y12 receptor occupancy of 87% +/- 5%. Surprisingly, a clopidogrel dose that produced a low standard IPA of 17% +/- 4% and P2Y12 receptor occupancy of 39% +/- 5% achieved a significant antithrombotic activity of 55% +/- 2% with a moderate increase in BT of 2.0 +/- 0.1-fold. This underestimation of clopidogrel efficacy by standard IPA was improved by measuring either modified IPA or P2Y12 receptor occupancy. These results suggest that in clopidogrel-treated rabbits, low standard IPA is associated with significant antithrombotic effects. Moreover, modified IPA and P2Y12 receptor occupancy appear to better predict the magnitude of clopidogrel's efficacy compared with standard IPA, which may be a better predictor of BT.

National Asthma Education and Prevention Program working group report on the quality of asthma care

The quality of asthma care is the second topic of the National Asthma Education and Prevention Program Task Force Report on the Cost Effectiveness, Quality of Care, and Financing of Asthma Care. This working group recommended an asthma continuous quality improvement model as an appropriate framework for examining the quality of asthma care. This model can be implemented by various organizations and providers of care in a variety of settings. The framework consists of four steps: (1) define the opportunity for improvement, (2) set the asthma quality improvement goals (outcomes), (3) characterize the process of care, and (4) begin the improvement cycle. Several case studies are presented to illustrate the use of this model in various settings, including managed care facilities, emergency departments, teaching hospitals, physician's offices, schools, workplaces, and communities. In addition, the appendix provides an overview of asthma outcome measures in the framework of patient-centered versus organizationally based perspectives.

Pharmacology of XR510, a potent orally active nonpeptide angiotensin II AT1 receptor antagonist with high affinity for the AT2 receptor subtype

The angiotensin II (Ang II) type 1 receptor (AT1) mediates all known physiological effects of ANG II, whereas functions of the type 2 (AT2) receptor are not clear. Should undesirable AT2 effects be identified, it may be advantageous to combine antagonism of AT1 and AT2 receptors. XR510 was shown to inhibit the specific binding of [125I]Sar1,Ile8-Ang II for AT1 and AT2 subtype binding sites in rat adrenal membranes with IC50 of 0.26 and 0.28 nM, respectively, and in human tissues with subnanomolar binding affinity. In isolated rabbit aorta, XR510 exerted insurmountable Ang II antagonism with a Kb value of 4 nM. In conscious renal hypertensive rats, XR510 decreased blood pressure (BP) with intravenous (i.v.) and oral (p.o.) ED30 of 0.08 and 0.27 mg/kg, respectively. In spontaneously hypertensive rats (SHR), repeated daily oral dosing of XR510, losartan, and enalapril at 30 mg/kg/day decreased BP similarly. In conscious furosemide-treated dogs, XR510, given either intravenously or orally, decreased BP. These results suggest that XR510 is an orally active and selective Ang II receptor antagonist with equal binding affinities for AT1 and AT2 receptor binding sites.