Amiodarone-induced pulmonary toxicity with an excellent response to treatment: A case report

Too Little, Too Late: A Case of a Swift Fatal Culmination of Amiodarone Induced Pulmonary Toxicity in an Adult Male

Amiodarone is a commonly prescribed antiarrhythmic drug. It can cause a myriad of complications associated with its long-term use, with amiodarone induced pulmonary toxicity being the worst. Amiodarone does this through its destructive properties and its' ability to accumulate if taken for extended periods of time or in high cumulative doses. Albeit uncommon, the management of amiodarone induced pulmonary toxicity can be straightforward if recognized early. Otherwise, it can lead to severe respiratory failure causing death. In this case report, we aim to highlight the importance of vigilance with clinicians prescribing amiodarone and to spark interests into research for alternative management options of amiodarone induced pulmonary toxicity. This will be done through the description of a case of a 64-year-old male presenting with cough and dyspnoea, who has been on a large dose of amiodarone daily for the past 11 months. He was diagnosed too little, too late, which unfortunately culminated in his rapid fatality. This case is unique for two reasons. The diagnosis of amiodarone induced pulmonary toxicity was through the clinical picture - without the use of invasive investigations. In addition, the futile cessation of amiodarone and use of high dose systemic corticosteroids as a management - which to our knowledge is uncommon in literature.

Suppressing NLRP3 activation and PI3K/AKT/mTOR signaling ameliorates amiodarone-induced pulmonary fibrosis in rats: a possible protective role of nobiletin

Amiodarone (AMD), a medicine used to treat life-threatening arrhythmias, is frequently linked to pulmonary fibrosis (PF). Despite the involvement of NLRP3 inflammasome and PI3K/Akt/mTOR axis in fibrosis modulation and development, their significance in the etiology of AMD-induced PF remains uncertain. Nobiletin (NOB), a citrus flavonoid, has recently gained attention for its ability to reduce fibrotic processes in a variety of organs through inhibiting NLRP3-associated inflammation and suppressing PI3K/AKT/mTOR fibrotic pathway. Therefore, this research aimed to investigate the possible beneficial impact of NOB against AMD-induced PF, taking into account the roles of NLRP3 and PI3K/AKT/mTOR axis in its pathogenesis. Twenty-four rats were randomly specified into Vehicle; NOB 20 mg/kg; AMD 30 mg/kg, and NOB + AMD. All treatments were administered orally once a day for 4 weeks. The lung oxidant/antioxidant status, as well as the expression of inflammatory and fibrotic markers were all assessed. The results revealed that NOB, by improving Nrf2/HO-1 pathway, could reduce ROS production and NLRP3 activation, which in turn hindered IL-1β release, prohibited TGF-β1-related PI3K/AKT/mTOR cascade, suppressed α-SMA expression, and impeded collagen deposition. These findings point to a novel strategy by which NOB may alleviate the AMD-prompted NLRP3 inflammatory responses and associated PF through blocking PI3K/AKT/mTOR signaling.

Pulmonary Fibrosis Related to Amiodarone-Is It a Standard Pathophysiological Pattern? A Case-Based Literature Review

Amiodarone hydrochloride is an antiarrhythmic drug, with proven efficacy in prevention and treatment of numerous arrhythmias, atrial fibrillation especially, or ventricular arrhythmias, with a long half-life (55-60 days). The increased risk of developing amiodarone-induced pulmonary fibrosis is directly related to the dose and the duration of the intake. Amiodarone-induced pulmonary toxicity is conditioned by dose, patient's age, and pre-existent pulmonary pathologies. The pattern for drug-induced lung injury may vary in many forms, but the amiodarone can cause polymorphous injuries such as diffuse alveolar damage, chronical interstitial pneumonia, organizing pneumonia, pulmonary hemorrhage, lung nodules or pleural disease. The pathological mechanism of pulmonary injury induced by amiodarone consists of the accumulation of phospholipid complexes in histocytes and type II pneumocytes. Differential diagnosis of pulmonary fibrosis induced by amiodarone is made mainly with idiopathic pulmonary fibrosis, left ventricular failure or infectious disease. Before starting treatment with amiodarone, patients should be informed of potential adverse effects and any new respiratory symptoms should promptly be reported to their family physician or attending physician. The assessment carried out at the initiation of amiodarone treatment should include at least chest X-ray and respiratory function tests and extrapulmonary evaluation.

Nano drugs delivery system: A novel promise for the treatment of atrial fibrillation

Atrial fibrillation (AF) is one of the most common sustained tachyarrhythmias worldwide, and its prevalence is positively correlated with aging. AF not only significantly reduces the quality of life of patients but also causes a series of complications, such as thromboembolism, stroke, and heart failure, increases the average number of hospitalizations of patients, and places a huge economic burden on patients and society. Traditional drug therapy and ablation have unsatisfactory success rates, high recurrence rates, and the risk of serious complications. Surgical treatment is highly traumatic. The nano drug delivery system has unique physical and chemical properties, and in the application of AF treatment, whether it is used to assist in enhancing the ablation effect or for targeted therapy, it provides a safer, more effective and more economical treatment strategy.

Acute respiratory failure on a low dose of amiodarone - is it an underdiagnosed and undertreated condition?

Amiodarone-induced pulmonary toxicity (AIPT) has a variety of presentations. Amiodarone use has been rarely associated with the development of acute respiratory failure. We present a patient with a history of paroxysmal atrial fibrillation who developed acute respiratory distress syndrome despite taking a low dose of amiodarone and having no risk or precipitating factors. The diagnosis of AIPT was made after drug discontinuation and exclusion of other potential causes. The development of acute respiratory failure due to AIPT is often underdiagnosed and undertreated. Better identification of risk factors and developing appropriate diagnostic tools for risk stratification of patients receiving amiodarone is mandatory.

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Amiodarone use is rarely associated with the development of acute respiratory failure.

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The most clinical presentation of AIPT is a subacute illness presented by the nonproductive cough, progressive dyspnoea, and low-grade fever

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The diagnosis of AIPT is often made after drug discontinuation and exclusion of other potential causes.

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Identification of risk factors and developing appropriate diagnostic tools for risk stratification of patients receiving amiodarone is mandatory

Crucial Role of PLGA Nanoparticles in Mitigating the Amiodarone-Induced Pulmonary Toxicity

BACKGROUND

Amiodarone (AMD) is a widely used anti-arrhythmic drug, but its administration could be associated with varying degrees of pulmonary toxicity. In attempting to circumvent this issue, AMD-loaded polymeric nanoparticles (AMD-loaded NPs) had been designed.

MATERIALS AND METHODS

AMD was loaded in NPs by the nanoprecipitation method using two stabilizers: bovine serum albumin and Kolliphor® P 188. The physicochemical properties of the AMD-loaded NPs were determined. Among the prepared NPs, two ones were selected for further investigation of spectral and thermal analysis as well as morphological properties. Additionally, in vitro release patterns were studied and kinetically analyzed at different pH values. In vitro cytotoxicity of an optimized formula (NP4) was quantified using A549 and Hep-2 cell lines. In vivo assessment of the pulmonary toxicity on Sprague Dawley rats via histopathological and immunohistochemical evaluations was applied.

RESULTS

The developed NPs achieved a size not more than 190 nm with an encapsulation efficiency of more than 88%. Satisfactory values of loading capacity and yield were also attained. The spectral and thermal analysis demonstrated homogeneous entrapment of AMD inside the polymeric matrix of NPs. Morphology revealed uniform, core-shell structured, and sphere-shaped particles with a smooth surface. Furthermore, the AMD-loaded NPs exhibited a pH-dependent and diffusion-controlled release over a significant period without an initial burst effect. NP4 demonstrated a superior cytoprotective efficiency by diminishing cell death and significantly increasing the IC50 by more than threefold above the pure AMD. Also, NP4 ameliorated AMD-induced pulmonary damage in rats. Significant downregulation of inflammatory mediators and free radicle production were noticed in the NP4-treated rats.

CONCLUSION

The AMD-loaded NPs could ameliorate the pulmonary injury induced by the pure drug moieties. Cytoprotective, anti-fibrotic, anti-inflammatory, and antioxidant properties were presented by the optimized NPs (NP4). Future studies may be built on these findings for diminishing AMD-induced off-target toxicities.

From the Heart to the Lung: A Case of Drug Toxicity

Patient: Female, 71-year-old

Final Diagnosis: Drug toxicity

Symptoms: Dry cough • dyspnea

Medication: —

Clinical Procedure: Drug withdrawal

Specialty: Pulmonology

Inhibitory Effects of Dronedarone on Small Conductance Calcium Activated Potassium Channels in Patients with Chronic Atrial Fibrillation: Comparison to Amiodarone

BACKGROUND Dysfunction of small conductance calcium activated potassium (SK) channels plays a vital role in atrial arrhythmogenesis. Amiodarone and dronedarone are the most effective class III antiarrhythmic drugs. It is unclear whether the antiarrhythmic effect of amiodarone and dronedarone is related to SK channel inhibition. MATERIAL AND METHODS Tissue samples were obtained from the right atria of 46 patients with normal sinus rhythm and 39 patients with chronic atrial fibrillation. Isolated atrial myocytes were obtained by enzymatic dissociation. KCNN2 (SK2) channels were transiently expressed in human embryonic kidney (HEK)-293 cells. SK currents were recorded using whole-cell conventional patch clamp techniques. RESULTS Amiodarone and dronedarone showed a concentration-dependent inhibitory effect on SK currents (IKAS) in atrial myocytes from normal sinus rhythm patients and chronic atrial fibrillation patients. The suppressed efficacy of dronedarone and amiodarone on IKAS was greater in atrial myocytes from chronic atrial fibrillation patients than that from normal sinus rhythm patients. Furthermore, in patients with chronic atrial fibrillation, the IC₅₀ value was 2.42 µM with dronedarone and 8.03 µM with amiodarone. In HEK-293 cells with transiently transfected SK2 channels, both dronedarone and amiodarone had a dose-dependent inhibitory effect on IKAS. The IC₅₀ value was 1.7 µM with dronedarone and 7.2 µM with amiodarone in cells from patients with chronic atrial fibrillation. Compared to amiodarone, dronedarone is more efficacy to inhibit IKAS and could be a potential intervention for patients with chronic atrial fibrillation. CONCLUSIONS Dronedarone provides a great degree of IKAS inhibition in atrial myocytes from chronic atrial fibrillation than amiodarone. IKAS might be a potential target of amiodarone and dronedarone for the management of chronic atrial fibrillation.