Engineering the Structure and Rheological Properties of P407 Hydrogels via Reverse Poloxamer Addition.

Aqueous solutions of poloxamer 407 (P407), a commercially available and nontoxic ABA triblock polymer (PEO-PPO-PEO), undergo a solution-to-gel transition with increasing temperature and are promising candidates for injectable therapeutics. The gel transition temperature, modulus, and structure are all dictated by polymer concentration, preventing independent tuning of these properties. Here, we show that addition of BAB reverse poloxamers (RPs) to P407-based solutions dramatically alters the gelation temperature, modulus, and morphology. Gelation temperature and RP localization within the hydrogel are dictated by RP solubility. Highly soluble RPs increase gelation temperature and incorporate primarily into the micelle corona regions. Alternatively, RPs with low aqueous solubility decrease gelation temperature and associate within the micelle core and core-corona interface. These differences in RP localization have significant implications for the hydrogel modulus and microstructure. The ability to tune gelation temperature, modulus, and structure through RP addition allows for the design of thermoresponsive materials with specific properties that are unobtainable with neat P407-based hydrogels.

Impact of small molecule and reverse poloxamer addition on the micellization and gelation mechanisms of poloxamer hydrogels.

Poloxamer 407 (P407) is widely used for targeted drug-delivery because it exhibits thermoresponsive gelation behavior near body temperature, stemming from a disorder-to-order transition. Hydrophobic small molecules can be encapsulated within P407; however, these additives often negatively impact the rheological properties and lower the gelation temperatures of the hydrogels, limiting their clinical utility. Here we investigate the impact of adding two BAB reverse poloxamers (RPs), 25R4 and 31R1, on the thermal transitions, rheological properties, and assembled structures of P407 both with and without incorporated small molecules. By employing a combination of differential scanning calorimetry (DSC), rheology, and small-angle x-ray scattering (SAXS), we determine distinct mechanisms for RP incorporation. While 25R4 addition promotes inter-micelle bridge formation, the highly hydrophobic 31R1 co-micellizes with P407. Small molecule addition lowers thermal transition temperatures and increases the micelle size, while RP addition mitigates the decreases in modulus traditionally associated with small molecule incorporation. This fundamental understanding yields new strategies for tuning the mechanical and structural properties of the hydrogels, enabling design of drug-loaded formulations with ideal thermal transitions for a range of clinical applications.

Integrated Management Program Advancing Community Treatment of Atrial Fibrillation (IMPACT-AF): A cluster randomized trial of a computerized clinical decision support tool.

BACKGROUND: Clinical decision support (CDS) tools designed to digest, filter, organize, and present health data are becoming essential in providing clinical and cost-effective care. Many are not rigorously evaluated for benefit before implementation. We assessed whether computerized CDS for primary care providers would improve atrial fibrillation (AF) management and outcomes as compared to usual care. METHODS: Overall, 203 primary care providers were recruited, randomized, and then cluster stratified by location (urban, rural) to usual care (n = 99) or CDS (n = 104). Providers recruited 1,145 adult patients with AF to participate. The intervention was access to an evidenced-based, point-of-care computerized CDS designed to support guideline-based AF management. The primary efficacy outcome was a composite of unplanned cardiovascular hospitalizations and AF-related emergency department visits; the primary safety outcome was major bleeding, both over 1 year. Patients were the units of intention-to-treat analysis. RESULTS: No significant effects on the primary efficacy (130 control, 118 CDS, hazard ratio: 0.98 [95% CI 0.71-1.37], P = .926) or safety (n = 7 usual care, n = 8 CDS, 1.3% total, P = .939) outcomes were observed at 12-months. CONCLUSIONS: IMPACT-AF rigorously assessed a CDS tool in a highly representative sample of primary care providers and their patients; however, no impact on outcomes was observed. Considering the proliferating use of CDS applications, this study highlights the need for efficacy assessments prior to adoption and clinical implementation.

A Pseudo-Surfactant Chemical Permeation Enhancer to Treat Otitis Media via Sustained Transtympanic Delivery of Antibiotics.

Chemical permeation enhancers (CPEs) represent a prevalent and safe strategy to enable noninvasive drug delivery across skin-like biological barriers such as the tympanic membrane (TM). While most existing CPEs interact strongly with the lipid bilayers in the stratum corneum to create defects as diffusion paths, their interactions with the delivery system, such as polymers forming a hydrogel, can compromise gelation, formulation stability, and drug diffusion. To overcome this challenge, differing interactions between CPEs and the hydrogel system are explored, especially those with sodium dodecyl sulfate (SDS), an ionic surfactant and a common CPE, and those with methyl laurate (ML), a nonionic counterpart with a similar length alkyl chain. Notably, the use of ML effectively decouples permeation enhancement from gelation, enabling sustained delivery across TMs to treat acute otitis media (AOM), which is not possible with the use of SDS. Ciprofloxacin and ML are shown to form a pseudo-surfactant that significantly boosts transtympanic permeation. The middle ear ciprofloxacin concentration is increased by 70-fold in vivo in a chinchilla AOM model, yielding superior efficacy and biocompatibility than the previous highest-performing formulation. Beyond improved efficacy and biocompatibility, this single-CPE formulation significantly accelerates its progression toward clinical deployment.

Effect of chain architecture on the structure, dynamics, and rheology of thermoresponsive poloxamer hydrogels and associated blends.

Poloxamers, ABA triblock polymers composed of a poly(propylene oxide) (PPO) midblock (B) and poly(ethylene oxide) (PEO) endblocks (A), are widely studied for biomedical applications. Aqueous poloxamer 407 (P407; also referred to as F127) undergoes a solution-to-gel transition with increasing temperature, driven by the formation and ordering of micelles onto periodic lattices; however, the gel temperature and resulting modulus has limited tunability. Here, reverse P407 (RP407), a BAB polymer of the same composition and molar mass but the inverted architecture, is synthesized via anionic polymerization. The micellization and gelation temperatures of RP407 are higher than that of P407 and the PPO endblocks allow for intermicelle bridging; however, both single-component solutions favor body-centered cubic (BCC) packings. Further, aqueous RP407 displays a "soft gel" region with interesting rheological behavior, including viscoelastic aging and thermal hysteresis. Combining P407 and RP407 yields solutions with intermediate transition temperatures and alters the size and micelle packing. While the single-component solutions produce BCC packings, the blends form close-packed structures and larger micelles of higher aggregation numbers. Blends of P407 with an analogous AB diblock (E111P32) display similar behavior, whereas RP407/diblock blends form intermediate-sized BCC-packed micelles. These differences in packing and aggregation alter the local environments within the gels, which could have implications for applications such as drug delivery and protein stabilization.

Rhythm Control Vs Rate Control in a Contemporary Ambulatory Atrial Fibrillation Cohort: Post Hoc Analysis of the IMPACT-AF Trial.

Background: We examined the characteristics and outcomes in a contemporary ambulatory population of patients with atrial fibrillation (AF), comparing rate control with rhythm control. Methods: This is a post hoc analysis of a cluster-randomized trial (Integrated Management Program Advancing Community Treatment of Atrial Fibrillation [IMPACT-AF]) in ambulatory AF patients from 2016 to 2018, which compared use of a clinical decision support tool for general practitioners to usual care. This analysis compared patients managed with rate vs rhythm control, at entry into the study. Outcomes included AF-related emergency department (ED) visits, unplanned cardiovascular hospitalizations, and bleeding events at 12 months. Results: A total of 870 patients were included in this analysis, 99 (11.4%) in the rhythm-control group, and 40% women. In the rhythm-control group, the mean age was younger (70 ± 11.4 vs 72.7 ± 9.5 years, P = 0.03), a higher number were paroxysmal (80% vs 43%, P < 0.001), and CHADS2 scores were lower. The rate of AF-related ED visits was higher in the rhythm-control group (17.2 vs 7.3%, P = 0.003), and repeat visits (rate ratio 3.03, 95% confidence interval [1.99-4.52], P < 0.001). The number of repeat ED visits was independently associated with female sex and being in the rhythm-control group. Conclusions: Both rate- and rhythm-control patients have recurrent ED visits, with a higher rate in patients treated with rhythm control. These findings are observational, but taken in the context of current guidelines could help develop further therapies aimed at improving symptom burden in both rhythm- and rate-control patients to broadly improve healthcare utilization in the AF population.

Contexte: Nous avons examiné les caractéristiques et le devenir de patients ambulatoires contemporains atteints de fibrillation auriculaire (FA) dans le cadre d'une comparaison entre la maîtrise de la fréquence cardiaque et la maîtrise du rythme cardiaque. Méthodologie: Nous avons effectué une analyse a posteriori d'un essai à répartition aléatoire par grappes ( I ntegrated M anagement P rogram A dvancing C ommunity T reatment of A trial F ibrillation [IMPACT-AF]) mené de 2016 à 2018 chez des patients ambulatoires atteints de FA en vue de comparer un outil d'aide à la décision clinique destiné aux omnipraticiens avec les soins habituels. Notre analyse a permis d'établir une comparaison entre les patients pris en charge par une maîtrise de la fréquence cardiaque et ceux pris en charge par une maîtrise du rythme cardiaque lors de leur inscription à l'essai. Les paramètres d'évaluation comprenaient les consultations aux urgences liées à la FA, les hospitalisations imprévues ayant des causes cardiovasculaires et les épisodes hémorragiques à 12 mois. Résultats: Au total, 870 patients ont été inclus dans cette analyse; 99 (11,4 %) faisaient partie du groupe pris en charge par une maîtrise du rythme cardiaque, et 40 % étaient de femmes. Dans le groupe pris en charge par une maîtrise du rythme cardiaque, l'âge moyen était moindre (70 ± 11,4 ans vs 72,7 ± 9,5 ans, P = 0,03), un plus grand nombre de patients présentaient une FA paroxystique (80 % vs 43 %, P < 0,001) et les scores CHADS2 étaient moins élevés. Le taux de consultations aux urgences liées à la FA était plus élevé dans le groupe pris en charge par une maîtrise du rythme cardiaque (17,2 vs 7,3 %, P = 0,003) tout comme le taux de consultations répétées aux urgences (rapport des taux de 3,03, intervalle de confiance à 95 % de 1,99 à 4,52, P < 0,001). Le nombre de consultations répétées aux urgences était indépendamment associé au sexe féminin et à l'inclusion dans le groupe pris en charge par une maîtrise du rythme cardiaque. Conclusions: Des consultations répétées aux urgences ont été notées tant chez les patients pris en charge par une maîtrise de la fréquence cardiaque que chez ceux pris en charge par une maîtrise du rythme cardiaque quoique plus fréquemment chez ces derniers. Nos constats sont de type observationnel. Néanmoins, dans le contexte des lignes directrices actuelles, ils pourraient contribuer à la mise au point d'autres traitements visant à atténuer le fardeau des symptômes tant chez les patients pris en charge par une maîtrise du rythme cardiaque que chez ceux pris en charge par une maîtrise de la fréquence cardiaque et ainsi permettre globalement une meilleure utilisation des soins de santé chez les patients atteints de FA.

Lessons learned from Integrated Management Program Advancing Community Treatment of Atrial Fibrillation (IMPACT-AF): a pragmatic clinical trial of computerized decision support in primary care.

BACKGROUND: Integrated Management Program Advancing Community Treatment of Atrial Fibrillation (IMPACT-AF) was a pragmatic, cluster randomized trial assessing the effectiveness of a clinical decision support (CDS) tool in primary care, Nova Scotia, Canada. We evaluated if CDS software versus Usual Care could help primary care providers (PCPs) deliver individualized guideline-based AF patient care. METHODS: Key study challenges including CDS development and implementation, recruitment, and data integration documented over the trial duration are presented as lessons learned. RESULTS: Adequate resources must be allocated for software development, updates and feasibility testing. Development took longer than projected. End-user feedback suggested network access and broadband speeds impeded uptake; they felt further that the CDS was not sufficiently user-friendly or efficient in supporting AF care (i.e., repetitive alerts). Integration across e-platforms is crucial. Intellectual property and other issues prohibited CDS integration within electronic medical records and provincial e-health platforms. Double login and data entry were impediments to participation or reasons for provider withdrawal. Data integration challenges prevented easy and timely data access, analysis, and reporting. Primary care study recruitment is resource intensive. Altogether, 203 PCPs and 1145 of their patients participated, representing 25% of eligible providers and 12% of AF patients in Nova Scotia, respectively. The most effective provider recruitment strategy was in-office, small group lunch-and-learns. PCPs with past research experience or who led patient consent were top recruiters. The study office played a pivotal role in achieving patient recruitment targets. CONCLUSIONS: A rapid growth in healthcare data is leading to widespread development of CDS. Our experience found practical issues to address for such applications to succeed. Feasibility testing to assess the utility of any healthcare CDS prior to implementation is recommended. Adequate resources are necessary to support successful recruitment for future pragmatic trials. CDS tools that integrate multiple co-morbid guidelines across eHealth platforms should be pursued. TRIAL REGISTRATION: ClinicalTrials.gov NCT01927367. Registered on August 22, 2013.