Lung disease little-known side effect of some drugs

COLUMBUS, Ohio

11/04/04

Any consumer who watches television or reads magazines is familiar with the list of possible side effects included in advertisements for new medications. One allergic-type of reaction associated with some drugs – a form of lung disease – has received comparatively little attention, but that may change as increasing numbers of new drugs are introduced in the marketplace.

“I think any time patients develop unexpected respiratory symptoms, one of the first places to look is their medication list,” said Dr. James Allen, a pulmonologist at The Ohio State University Medical Center and medical director of its pulmonary diagnostic lab. “We do have a lot of great new medications, but along with those new medications and treatments comes the potential for side effects – and side effects can occur when you least expect them.”

In these instances, the disorder is called drug-induced eosinophilic lung disease, meaning it involves the presence of excess eosinophils in the lungs. Eosinophils are a variety of white blood cells normally present in the body that play a role in allergic reactions and defense against parasites. They can cause trouble when they increase in the lungs as a response to infection or other irritants, and are associated with drug-induced disease when a respiratory illness can be traced to the introduction of a new medication.

Symptoms of this disorder look like many other respiratory illnesses, Allen notes: Coughing and shortness of breath are the most common complaints. When other lung illnesses are ruled out, drug-induced eosinophilic lung disease can be diagnosed through an assessment of a patient’s history, a complete blood count and a basic chest X-ray, he said.

Once a drug-induced lung illness is diagnosed, the first “treatment” is elimination of the cause: The patient must stop taking the drug that led to the reaction. Some patients also require a course of corticosteroids to hasten recovery. In rare cases, a severe reaction can lead to respiratory failure.

“The good news is, when this is recognized early, a patient can recover completely,” said Allen, also the Battelle professor of inhalational therapeutics at OSU Medical Center. “But if it is left untreated for too long, scarring can occur, and that’s what we want to avoid.”

Allen, who was among a team of physicians who first identified acute eosinophilic pneumonia as a reversible cause of noninfectious respiratory failure in 1989, said the incidence of drug-induced eosinophilic lung disease appears to be on the rise.

“I think we’re seeing more cases because we recognize them more quickly. Also, there are new medications being developed all the time, increasing the potential for allergic reactions to occur,” Allen said. “When someone has unexplained coughing and shortness of breath, it’s important to keep the possibility of a drug reaction in mind.”

Though other respiratory illnesses such as emphysema and asthma are not predictors for who will be more susceptible to these types of lung diseases, known allergies to certain types of drugs could make patients more likely to have a reaction to any chemically similar agents.

Allen noted drug-induced eosinophilic lung disease is associated with not just prescription drugs, but also over-the-counter medicines and even herbal remedies. Among the classes of drugs known to be associated with these types of lung diseases are some heart medications, chemotherapy agents, antibiotics and nonsteroidal anti-inflammatory drugs.

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