while on amiodarone

while on amiodarone

8 months after stopping amiodarone

8 months after stopping amiodarone

This can occur in 5% of patients who receive amiodarone. It is fatal in 5% of cases.

There are two types- insidious onset and sudden onset. Insidious onset is also called interstitial pneumonitis and sudden onset is also called ARDS. In insidious onset variety, chest X-ray shows mainly interstitial shadows while in the sudden onset variety, alveolar shadows predominate.

The main symptoms are dyspnoea, non-productive cough, pleuritic chest pain and weight loss. Fever is more likely to occur in the sudden onset group. The main sign is crepitations. Sometimes, pleural rub is also heard.

Total WBC count may be elevated. ESR is usually elevated, absence of which questions the diagnosis.

Chest X-ray shows bilateral diffuse changes- usually a combination of infiltrative and alveolar shadows, though either of these may predominate. Pleural effusion and hilar adenopathy are conspicuous by their absence.

Pulmonary function tests show restrictive lung disease with reduction in total lung capacity and in diffusion capacity of carbon monoxide.

CT chest is sensitive to diagnose lung disease. It can also quantify the amount of iodine in the lungs, although this does not imply causation.

Gallium scan shows inflammatory activity in the lungs.

CT chest and gallium scan are not specific enough for diagnosing amiodarone lung disease.

Bronchoalveolar lavage shows two important findings- foam cells and CD8+ cells. Foam cells are macrophages having lamellar phospholipid laden bodies in the cytoplasm. Absence of foam cells rules out amiodarone induced lung disease while presence does not diagnose it as it can occur in other diseases also. CD8+ lymphocyte predominance also is highly sensitive for the diagnosis.

Bronchoscopic biopsy shows fibrosis in interstitium and alveoli.

When the disease is diagnosed, amiodarone should be stopped unless there is a pressing indication in which case, it may be given at a lower dose. Steroids are useful, the usually given agent being prednisolone 40 to 60 mg/day tapered to stop over 2 to 6 months.

Prevention is by close monitoring for symptoms by careful history taking every 3 months. Before starting amiodarone, a baseline chest X-ray should be taken for future reference. The chance of developing amiodarone induced lung disease is increased 10 fold in those with baseline lung disease. So, in these patients, some other drug should be given, if possible. The chance of amiodarone induced lung disease is more if amiodarone is given in a dose of 400 mg/day or more. So, if possible a lower dose is to be given, even though it is now being appreciated that even with a dose of 200 mg/day amiodarone induced lung disease can occur, even though the chance is lesser than with a higher dose. Also, the chance of amiodarone induced lung disease is more if amiodarone is given for a long duration. So, we have to carefully monitor patients on long term amiodarone.