Epicardial application of an amiodarone-releasing hydrogel to suppress atrial tachyarrhythmias

Innovative Epicardial Bigels Containing Amiodarone Hydrochloride: Pharmacotechnical and Analytical Characterization

BACKGROUND/OBJECTIVES

The search for novel ways of providing treatment also targets the development of formulations used in drug delivery. Among the important characteristics of pharmaceutical gels are their ability to penetrate membranes, their capability to offer rapid response, and their capacity to avoid the hepatic metabolization route followed by many drugs. Bigels combine the advantages of both hydrogels and oleogels, creating a biphasic system that might improve the solubility of amiodarone in water, which is otherwise poorly soluble. This study aimed to succeed in formulating stable amiodarone hydrochloride bigels (coded from ABG1-ABG6) destined for atrial application and evaluating them from a pharmacotechnical perspective.

METHODS

Three of the six initial formulations presented stability and underwent studies of spreadability, rheology, drug content, textural properties, and microbiological activity. A statistical analysis was performed on penetrometry and drug assay data.

RESULTS

The spreadability varied from 1734.07 mm2 (ABG1) to 2163.85 mm2 (ABG6), while the drug concentration ranged between 1.35 and 1.49% (w/w). The textural profile analysis highlighted superior hardness, cohesiveness, and resilience for ABG6 and higher adhesion for ABG2. Both presented pseudoplastic thixotropic behavior, while a plastic thixotropic flow was registered in the case of ABG1.

CONCLUSIONS

All three bigels are suitable for amiodarone incorporation; however, the influence of the type of ingredients chosen on the texture and properties of the formulations was reflected in the data gathered upon evaluation.

Effectiveness of intra-operative topical amiodarone for prevention of postcardiac surgery new-onset atrial fibrillation: A review of current evidence

BACKGROUND

Postoperative atrial fibrillation (POAF) is one of the most common complications following cardiac surgery and is associated with increased morbidity. Intraoperative topical amiodarone application on epicardial tissue has been shown to reduce systemic concentrations while maintaining therapeutic myocardial concentrations, thereby, lowering the risk of extracardiac adverse effects associated with oral and intravenous amiodarone therapy. However, the efficacy and safety of topical amiodarone in preventing POAF is unclear.

OBJECTIVES

This study summarizes the clinical studies to-date that have investigated the efficacy and safety of topical amiodarone administration in preventing POAF following cardiac surgery.

METHODS

A database search was conducted using Medline, Embase, and Cochrane Library to identify relevant studies. Abstracts were screened and data were extracted from relevant full-text articles that met the inclusion and exclusion criteria.

RESULTS

The search returned four studies with variable findings on the effect of topical amiodarone therapy on the incidence of POAF, cardiac effects, extracardiac effects, and hospital length of stay.

CONCLUSION

Prophylactic topical application of amiodarone may be effective and safe for preventing post-operative new-onset atrial fibrillation. Further investigation is required to evaluate the efficacy and safety of topical amiodadrone therapy before it can be widely integrated into current practice.

Access routes, devices and guidance methods for intrapericardial delivery in cardiac conditions

Drug deposition into the intrapericardial space is favourable for achieving localised effects and targeted cardiac delivery owing to its proximity to the myocardium as well as facilitating optimised pharmacokinetic profiles and a reduction in systemic side effects. Access to the pericardium requires invasive procedures but the risks associated with this have been reduced with technological advances, such as combining transatrial and subxiphoid access with different guidance methods. A variety of introducer devices, ranging from needles to loop-catheters, have also been developed and validated in pre-clinical studies investigating intrapericardial delivery of therapeutic agents. Access techniques are generally well-tolerated, self-limiting and safe, although some rare complications associated with certain approaches have been reported. This review covers these access techniques and how they have been applied to the delivery of drugs, cells, and biologicals, demonstrating the potential of intrapericardial delivery for treatments in cardiac arrhythmia, vascular damage, and myocardial infarction.

Local Use of Hydrogel with Amiodarone in Cardiac Surgery: Experiment and Translation to the Clinic

The objective of this study was to study the use of the hydrogel biopolymer based on sodium alginate ("Colegel") with a drug substance-amiodarone-for the prevention of postoperative atrial fibrillation (POAF) in cardiac surgery. The experimental part of the study was performed on 46 rabbits. Five groups were formed: in the first group, the dose of amiodarone in hydrogel was 1 mg; in the second group-3 mg; in the third group-6 mg; in the fourth group, hydrogel was used without amiodarone; in the fifth group, 60 mg amiodarone was administered intravenously. The animals from each group were removed from the experiment for the pathomorphological study of the heart after 3, 7 and 14 days. The studied endpoints were: the heart rate control; the development of the blockades of the conduction system of the heart; and the development of inflammation according to laboratory pathomorphological studies. The translational clinical part involved a randomized clinical trial which included 60 patients, with an average age of 62 ± 8.5 years. All patients were randomized into two groups: the study group (n = 30, with the application of amiodarone hydrogel) and the control group (n = 30, without the application of amiodarone hydrogel). The dose of amiodarone in the hydrogel material was 60 mg for all patients. The heart rhythm was monitored during 5 days. The primary endpoint was the development of POAF. Secondary endpoints were: the dynamics of heart rate; the duration of the QT and PQ intervals; the development of blockades of the cardiac conduction system; as well as the dynamics of AST and ALT. According to the results of the experimental part, it was found that the method of the local epicardial delivery of amiodarone by the hydrogel material was safe. Hydrogel with amiodarone is effective for reducing the heart rate in the animal experiment in comparison to the control group and the group with the intravenous administration of the drug. The optimal dose of amiodarone in hydrogel was 1 mg per 1 kg. According to the results of the clinical part, it was found that the method of the local epicardial delivery of amiodarone as a hydrogel material proved its safety. Hydrogel with amiodarone at a dose of 60 mg was effective in preventing POAF in patients after coronary artery bypass grafting (CABG) operations in comparison to the control group (p < 0.001). The age and procedure of application of the amiodarone gel were significantly associated with POAF (p = 0.009 and p = 0.011, respectively). The use of hydrogel with amiodarone reduced the probability of developing POAF 18.9-fold. The method of the local epicardial delivery of amiodarone in the form of a hydrogel material is safe. The use of hydrogel with amiodarone after CABG reduced the probability of developing POAF.

Technologies for intrapericardial delivery of therapeutics and cells

The pericardium, which surrounds the heart, provides a unique enclosed volume and a site for the delivery of agents to the heart and coronary arteries. While strategies for targeting the delivery of therapeutics to the heart are lacking, various technologies and nanodelivery approaches are emerging as promising methods for site specific delivery to increase therapeutic myocardial retention, efficacy, and bioactivity, while decreasing undesired systemic effects. Here, we provide a literature review of various approaches for intrapericardial delivery of agents. Emphasis is given to sustained delivery approaches (pumps and catheters) and localized release (patches, drug eluting stents, and support devices and meshes). Further, minimally invasive access techniques, pericardial access devices, pericardial washout and fluid analysis, as well as therapeutic and cell delivery vehicles are presented. Finally, several promising new therapeutic targets to treat heart diseases are highlighted.

Minimally Invasive Delivery of Hydrogel-Encapsulated Amiodarone to the Epicardium Reduces Atrial Fibrillation

BACKGROUND

Atrial fibrillation (AF) is the most common cardiac arrhythmia. Although treatment options for AF exist, many patients cannot be maintained in normal sinus rhythm. Amiodarone is an effective medication for AF but has limited clinical utility because of off-target tissue toxicity.

METHODS

Here, we use a pig model of AF to test the efficacy of an amiodarone-containing polyethylene glycol-based hydrogel. The gel is placed directly on the atrial epicardium through the pericardial space in a minimally invasive procedure using a specially designed catheter.

RESULTS

Implantation of amiodarone-containing gel significantly reduced the duration of sustained AF at 21 and 28 days; inducibility of AF was reduced 14 and 21 days post-delivery. Off-target organ drug levels in the liver, lungs, thyroid, and fat were significantly reduced in animals treated with epicardial amiodarone gel compared with systemic controls in small-animal distribution studies.

CONCLUSIONS

The pericardium is an underutilized therapeutic site and may be a new treatment strategy for AF and other cardiovascular diseases.

A novel approach to devise the therapy for ventricular fibrillation by epicardial delivery of lidocaine using active hydraulic ventricular attaching support system: An experimental study in rats

Active hydraulic ventricular attaching support system (ASD) placed around the heart is not only a novel, nontransplant surgical device used for epicardial administration of drugs like lidocaine, but also a promising treatment option for ventricular fibrillation (VF) and arrhythmias. We hypothesize that lidocaine in 5 mg/kg dose released by ASD significantly improves the VF in the rat model. Sprague-Dawley (SD) rats were selected and were divided into four groups, intravenous injection (IV), epicardial infusion (EI), ASD, and control. ASD group was further divided into four subgroups for different lidocaine doses (i) ASD+A group (10 mg/kg), (ii) ASD+B group (5 mg/kg), (iii) ASD+C group (1 mg/kg), and (iv) ASD+D group (0.1 mg/kg). VF was induced with calcium chloride injection and was confirmed by electrocardiogram (ECG) in all the groups. VF was treated with different doses of lidocaine using different modes of administration. Data were analyzed using the SPSS 19.0 Chi-square tests and one-way analysis of variance (ANOVA). The Kaplan-Meier curve for OS was compared to the Logrank test based on the survival time. P < 0.05 was considered as statistically significant. ASD + B group (5 mg/kg) showed significantly reduced sgroup. The time of first sinus rhythm recovered (15.96 ± 21.77 min) and ▵T-SOD in plasma (-42.02 ± 26.99 U/mL) was significantly different than that of control, IV, and EI groups. ▵T-SOD in plasma for all ASD-treated groups was smaller than the control and IV groups. This study proves that ASD with 5 mg/kg lidocaine dose appears as a promising therapeutic platform for treating VF in rats. Furthermore, ASD may also have potential for treating VF or other cardiovascular disease with different therapeutic agents. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1722-1731, 2019.

Topical amiodarone during cardiac surgery: Does epicardial application of amiodarone prevent postoperative atrial fibrillation?

OBJECTIVES

Atrial fibrillation (AF) is a common complication after cardiac surgery. Topical amiodarone on the epicardium may help prevent postoperative AF while avoiding the side effects of its systemic administration. The purpose of this study was to evaluate the all-comer strategy of epicardial amiodarone application for the prevention of postoperative AF.

METHODS

A retrospective observational study was performed that evaluated the incidence of new-onset AF in a consecutive series of cardiac surgery patients who were treated with either no amiodarone (historical control, n = 100), epicardial application of amiodarone mixed in a topical hydrogel (n = 50), or epicardial application of an amiodarone-soaked sealant patch (n = 50). Perioperative data were compared between the 3 groups, with all patients receiving continuous postoperative telemetry to monitor for new-onset AF.

RESULTS

The cohort consisted of 200 cardiac surgery patients (coronary bypass 82%, valve surgery 24%) who had no history of AF (mean age 71.0 years, 28% female). Among the 3 groups, the incidence of postoperative AF did not significantly differ, with 29 of 100 (29%) patients in the historical control group having new AF, compared with 18 of 50 (36%) in the amiodarone-hydrogel group, and 18 of 50 (36%) in the amiodarone-patch group (P = .56). The results did not differ when the analysis was restricted to coronary bypass patients only (n = 142, 27% vs 38% vs 32%, no-amiodarone vs amiodarone-hydrogel vs amiodarone-patch, respectively, P = .56). In multivariate logistic regression analysis, only older age (P = .001) was significantly associated with new-onset AF, but the use of topical amiodarone was not.

CONCLUSIONS

Routine epicardial application of topical amiodarone was not associated with a reduction in the incidence of new-onset postoperative AF in this observational study of older patients, leading us to question its role in contemporary cardiac surgical practice.

Delivery of drugs, growth factors, genes and stem cells via intrapericardial, epicardial and intramyocardial routes for sustained local targeted therapy of myocardial disease

INTRODUCTION

Local myocardial delivery (LMD) of therapeutic agents is a promising strategy that aims to treat various myocardial pathologies. It is designed to deliver agents directly to the myocardium and minimize their extracardiac concentrations and side effects. LMD aims to enhance outcomes of existing therapies by broadening their therapeutic window and to utilize new agents that could not be otherwise be implemented systemically. Areas covered: This article provides a historical overview of six decades LMD evolution in terms of the approaches, including intrapericardial, epicardial, and intramyocardial delivery, and the wide array of classes of agents used to treat myocardial pathologies. We examines delivery of pharmaceutical compounds, targeted gene transfection and cell implantation techniques to produce therapeutic effects locally. We outline therapeutic indications, successes and failures as well as technical approaches for LMD. Expert opinion: While LMD is more complicated than conventional oral or intravenous administration, given recent advances in interventional cardiology, it is safe and may provide better therapeutic outcomes. LMD is complex as many factors impact pharmacokinetics and biologic result. The choice between routes of LMD is largely driven not only by the myocardial pathology but also by the nature and physicochemical properties of the therapeutic agents.

A Plasma-Based, Amiodarone-Impregnated Material Decreases Susceptibility to Atrial Fibrillation in a Post-Cardiac Surgery Model

OBJECTIVE

This study aimed to test the impact of a plasma-based, material (PBM) impregnated with amiodarone on atrial electrophysiology and atrial fibrillation susceptibility in a porcine post-cardiac surgery model.

METHODS

Ten healthy pigs underwent implantation of transvenous pacing systems, after which sterile talc was infused into the pericardial sac via a pericardiotomy. In five animals, PBM was applied to the atrial epicardial surface just before talc infusion. Electrophysiologic evaluations were performed using the pacing system immediately after chest closure and 7 days later. Atrial histologic evaluations were performed.

RESULTS

Immediately after chest closure, there were no significant differences in electrophysiologic parameters between talc-only and talc + PBM animals, and atrial fibrillation was largely noninducible. On postsurgical day 7, electrophysiologic evaluation revealed significantly shorter sinus cycle length and atrioventricular nodal refractoriness among talc-only animals relative to talc + PBM animals, possibly suggesting attenuated sympathetic nervous system activation in the latter. Atrial fibrillation inducibility and duration were significantly greater among talc-only animals. No significant differences in atrial refractoriness or conduction time between groups were apparent. Histologic evaluation revealed a relative reduction in epicardial inflammation and less myolysis among talc + PBM animals.

CONCLUSIONS

Epicardial application of a plasma-based, amiodarone-impregnated material was associated with a significant reduction in atrial inflammation and susceptibility to fibrillation.

Combinatorial release of dexamethasone and amiodarone from a nano-structured parylene-C film to reduce perioperative inflammation and atrial fibrillation

Suppressing perioperative inflammation and post-operative atrial fibrillation requires effective drug delivery platforms (DDP). Localized anti-inflammatory and anti-arrhythmic agent release may be more effective than intravenous treatment to improve patient outcomes. This study utilized a dexamethasone (DEX) and amiodarone (AMIO)-loaded Parylene-C (PPX) nano-structured film to inhibit inflammation and atrial fibrillation. The PPX film was tested in an established pericardial adhesion rabbit model. Following sternotomy, the anterior pericardium was resected and the epicardium was abraded. Rabbits were randomly assigned to five treatment groups: control, oxidized PPX (PPX-Oxd), PPX-Oxd infused with DEX (PPX-Oxd[DEX]), native PPX (PPX), and PPX infused with DEX and AMIO (PPX[AMIO, DEX]). 4 weeks post-sternotomy, pericardial adhesions were evaluated for gross adhesions using a 4-point grading system and histological evaluation for epicardial neotissue fibrosis (NTF). Atrial fibrillation duration and time per induction were measured. The PPX[AMIO, DEX] group had a significant reduction in mean adhesion score compared with the control group (control 2.75 ± 0.42 vs. PPX[AMIO, DEX] 0.25 ± 0.42, P < 0.001). The PPX[AMIO, DEX] group was similar to native PPX (PPX 0.38 ± 0.48 vs. PPX[AMIO, DEX] 0.25 ± 0.42, P=NS). PPX-Oxd group adhesions were indistinguishable from controls (PPX-Oxd 2.83 ± 0.41 vs. control 2.75 ± 0.42, P=NS). NTF was reduced in the PPX[AMIO, DEX] group (0.80 ± 0.10 mm) compared to control (1.78 ± 0.13 mm, P < 0.001). Total duration of atrial fibrillation was decreased in rabbits with PPX[AMIO, DEX] films compared to control (9.5 ± 6.8 s vs. 187.6 ± 174.7 s, p = 0.003). Time of atrial fibrillation per successful induction decreased among PPX[AMIO, DEX] films compared to control (2.8 ± 1.2 s vs. 103.2 ± 178 s, p = 0.004). DEX/AMIO-loaded PPX films are associated with reduced perioperative inflammation and a diminished atrial fibrillation duration. Epicardial application of AMIO, DEX films is a promising strategy to prevent post-operative cardiac complications.

Effectiveness of biatrial epicardial application of amiodarone-releasing adhesive hydrogel to prevent postoperative atrial fibrillation

OBJECTIVE

Postoperative atrial fibrillation (POAF) is the most frequent complication arising after cardiac surgery, occurring in 30% of cases. Amiodarone is the most effective drug for prophylaxis and treatment. However, because of significant extracardiac side effects, only high-risk patients are eligible for prophylactic amiodarone therapy. We performed a randomized prospective study of 100 patients undergoing cardiac surgery with epicardial application of amiodarone-releasing hydrogel to determine the effectiveness of preventing POAF.

METHODS

After institutional review board approval, 100 patients, from January 2012 to July 2013, who had undergone cardiac surgery, were randomized to 2 equal groups. The study group received poly-based hydrogel with amiodarone sprayed diffusely over the epicardium. The control group underwent the procedure without the spray. Continuous telemetry monitored for POAF, and amiodarone levels in the atria, plasma, and tissue were measured postoperatively. Daily electrocardiographic parameters were measured until postoperative day 14.

RESULTS

The incidence of POAF was significantly less in the study group, with 4 of 50 patients (8%) incurring atrial fibrillation compared with 13 of 50 patients (26%) in the control group (P < .01). The mean amiodarone concentrations in the atria (12.06 ± 3.1) were significantly greater than those in the extracardiac tissues (1.32 ± 0.9; P < .01). The plasma amiodarone levels remained below the detection limit (<8 μg/mL) during the 14 days of follow-up. Bradycardia was observed less in the study group (76 ± 29) than in the control group (93 ± 18; P < .01).

CONCLUSIONS

Epicardial application of amiodarone-releasing adhesive hydrogel is a less invasive, well-tolerated, quick, and effective therapeutic option for preventing POAF at minimal risk of extracardiac adverse side effects.

Hydrogels for tissue engineering and regenerative medicine

Injectable hydrogels have become an incredibly prolific area of research in the field of tissue engineering and regenerative medicine, because of their high water content, mechanical similarity to natural tissues, and ease of surgical implantation, hydrogels are at the forefront of biomedical scaffold and drug carrier design.