Amiodarone increases the accumulation of DEA in a human alveolar epithelium-derived cell line

In vivo and cellular antiarrhythmic and cardiac electrophysiological effects of desethylamiodarone in dog cardiac preparations

BACKGROUND AND PURPOSE

The aim of the present study was to study the antiarrhythmic effects and cellular mechanisms of desethylamiodarone (DEA), the main metabolite of amiodarone (AMIO), following acute and chronic 4-week oral treatments (25-50 mg·kg^-1 ·day^-1 ).

EXPERIMENTAL APPROACH

The antiarrhythmic effects of acute iv. (10 mg·kg^-1 ) and chronic oral (4 weeks, 25 mg·kg^-1 ·day^-1 ) administration of DEA were assessed in carbachol and tachypacing-induced dog atrial fibrillation models. Action potentials were recorded from atrial and right ventricular tissue following acute (10 μM) and chronic (p.o. 4 weeks, 50 mg·kg^-1 ·day^-1 ) DEA application using the conventional microelectrode technique. Ionic currents were measured by the whole cell configuration of the patch clamp technique in isolated left ventricular myocytes. Pharmacokinetic studies were performed following a single intravenous dose (25 mg·kg^-1 ) of AMIO and DEA intravenously and orally. In chronic (91-day) toxicological investigations, DEA and AMIO were administered in the oral dose of 25 mg·kg^-1 ·day^-1 ).

KEY RESULTS

DEA exerted marked antiarrhythmic effects in both canine atrial fibrillation models. Both acute and chronic DEA administration prolonged action potential duration in atrial and ventricular muscle without any changes detected in Purkinje fibres. DEA decreased the amplitude of several outward potassium currents such as I_Kr , I_Ks , I_K1 , I_to , and I_KACh , while the I_CaL and late I_Na inward currents were also significantly depressed. Better drug bioavailability and higher volume of distribution for DEA were observed compared to AMIO. No neutropenia and less severe pulmonary fibrosis was found following DEA compared to that of AMIO administration.

CONCLUSION AND IMPLICATIONS

Chronic DEA treatment in animal experiments has marked antiarrhythmic and electrophysiological effects with better pharmacokinetics and lower toxicity than its parent compound. These results suggest that the active metabolite, DEA, should be considered for clinical trials as a possible new, more favourable option for the treatment of cardiac arrhythmias including atrial fibrillation.

Acute Amiodarone Pulmonary Toxicity

Amiodarone is an effective antiarrhythmic that frequently is used during the perioperative period. Amiodarone possesses a significant adverse reaction profile. Amiodarone-induced pulmonary toxicity (AIPT) is among the most serious adverse effects and is a leading cause of death associated with its use. Despite significant advances in the understanding of AIPT, its etiology and pathogenesis remain incompletely understood. The diagnosis of AIPT is one of exclusion. The clinical manifestations of AIPT are categorized broadly as acute, subacute, and chronic. Acute AIPT is a rarer and more aggressive form of the disease, most often encountered in cardiothoracic surgery. Acute respiratory distress syndrome (ARDS) is the predominating pattern of amiodarone's acute pulmonary toxicity. The incidence, risk factors, pathogenesis, and diagnosis of acute AIPT are speculative. Early cardiothoracic literature investigating AIPT often attributed amiodarone to the development of postoperative ARDS. Subsequent studies have found no association between amiodarone and acute AIPT and ARDS development. As a drug that is frequently prescribed to a patient population deemed most at risk for this fatal disease, the conflicting evidence on acute AIPT needs further investigation and clarification.

Amiodarone-induced diffuse alveolar haemorrhage: a rare but potentially life-threatening complication of a commonly prescribed medication

Amiodarone is an antiarrhythmic agent that is used commonly in clinical practice. It is associated with many side effects, the most common being pulmonary manifestations. Interstitial pneumonitis is one of the most common complications, however rarely amiodarone can cause diffuse alveolar haemorrhage (DAH) too. We describe the case of a 73-year-old woman who presented with shortness of breath and haemoptysis 4 days after starting amiodarone. She was diagnosed with amiodarone-induced DAH based on imaging and bronchoalveolar lavage. She was treated with intravenous and then oral steroids, and amiodarone was discontinued. The patient made a significant clinical and radiological recovery. She was discharged 10 days after her presentation. This case highlights a rare but potentially life-threatening complication of a commonly used medication.

A case report and literature review: previously excluded tuberculosis masked by amiodarone induced lung injury

Background

Amiodarone is an antiarrhythmic drug which is used to treat and prevent several dysrhythmias. This includes ventricular tachycardia and fibrillation, wide complex tachycardia, as well as atrial fibrillation (AF) and paroxysmal supraventricular tachycardia. Amiodarone may prove to be the agent of choice where the patient is hemodynamically unstable and unsuitable for direct current (DC) cardioversion. Although, it is not recommended for long-term use. The physician might encounter issues when differentiating amiodarone-induced lung toxicity with suspicion of interstitial lung disease, cancer or vasculitis. Adverse drug reactions are difficult to confirm and it leads to serious problems of pharmacotherapy.

Case presentation

A 78-year-old Caucasian male pensioner complaining of fever, dyspnea, malaise, non-productive cough, fatigue, weight loss, diagnosed with acute respiratory failure with a 16-year long history of amiodarone use and histologically confirmed temporal arteritis with long-term glucocorticosteroid (GCC) therapy.

Patient was treated for temporal arteritis with GCC for ~ 1 year, then fever and dyspnea occurred, and the patient was hospitalized for treatment of bilateral pneumonia. Chest X-ray and chest high resolution computed tomography (HRCT) indicated several possible diagnoses: drug-induced interstitial lung disease, autoimmune interstitial lung disease, previously excluded pulmonary TB. Amiodarone was discontinued. Antibiotic therapy for bilateral pneumonia was started. Fiberoptic bronchoscopy with bronchial washings and brushings was performed. Acid fast bacilli (AFB) were found on Ziehl-Nielsen microscopy and tuberculosis (TB) was confirmed (later confirmed to be Mycobacterium tuberculosis in culture), initial treatment for TB was started. After a few months of treating for TB, patient was diagnosed with pneumonia and sepsis, empiric antibiotic therapy was prescribed.

After reevaluation and M. Tuberculosis identification, the patient was referred to the Tuberculosis hospital for further treatment. After 6 months of TB treatment, pneumonia occurred which was complicated by sepsis. Despite the treatment, multiple organ dysfunction syndrome evolved and patient died. Probable cause of death: pneumonia and sepsis.

Conclusions

The current clinical case emphasizes issues that a physician may encounter in the differential diagnostics of amiodarone-induced lung toxicity with other lung diseases.

Amiodarone-induced acute respiratory distress syndrome masquerading as acute heart failure

BACKGROUND

Amiodarone use has been rarely associated with the development of acute respiratory distress syndrome (ARDS), usually in association with surgery or pulmonary angiography. In patients with preexisting left ventricular dysfunction, the diagnosis may be overlooked.

CASE REPORT

A 92-year-old woman with a history of atrial fibrillation who was on low-dose amiodarone presented to the Emergency Department with sudden onset of shortness of breath. The patient was started on treatment for acute heart failure based on the physical examination and the elevated brain natriuretic peptide level. Despite adequate diuresis, the patient showed no improvement. A chest computed tomography scan revealed acute interstitial pneumonitis. The patient received corticosteroids due to suspected amiodarone-induced acute interstitial pneumonitis resulting in ARDS. She returned to her baseline activity within 2 weeks of the therapy.

CONCLUSION

Although rare, clinicians should be vigilant for amiodarone-induced acute interstitial pneumonitis resulting in ARDS, as delay in treatment may result in a high risk of mortality. In addition, the development of ARDS occurred in our patient in the absence of precipitating factors such as surgery or pulmonary angiography.