Inactive Ingredients in Drugs May Be Less Inactive Than You Think

Henrietta Strickland
March 15, 2019

A new study reveals that a majority of the frequently prescribed medication in the United States contain at least one inactive ingredient that could cause an allergic or gastrointestinal reaction in sensitive patients. A pending Food and Drug Administration proposal recommends adding gluten information to drug labels. "Oftentimes the medications are being withheld from patients who say they're allergic to eggs or soy or something else that may be in the medication", Kelso says, "but it is actually not a problem".

Dr. Giovanni Traverso, one of the study's authors, began his research several years ago after hearing about a patient with celiac disease who was prescribed medicine for a different condition. They concluded that, on average, about 75 percent of a pill or capsule is made up of inactive ingredients - that is, material other than the chemical or chemicals that determine the therapeutic effect of a drug. "We wanted to understand the problem and drill down to characterize the entire universe of inactive ingredients across thousands of drugs".

Currently, when doctors write a prescription, they specify the type and dosage of the active pharmaceutical, but nothing about the inactive ingredients.

All ingredients, active or inactive, in a drug have to be disclosed, either on the label, the package or in the package insert.

The National Library of Medicine also has an online database, called Pillbox, with this information. But many people take multiple medicines, and if those drugs contain the same inactive ingredients, the doses can add up.

And yet, a 2013 study of the top 200 most-prescribed drugs found that the majority had some amount of gluten in them - however small - that could have sickened a person with celiac disease.

So Traverso and his team chose to review the ingredients behind some of the most commonly prescribed drugs taken orally in the U.S. These drugs included simvastatin, a cholesterol-lowering medication; gabapentin, an anti-seizure drug also used to treat nerve pain; and amoxicillin, a widely used antibiotic. "There are hundreds of different versions of pills or capsules that deliver the same medication using a different combination of inactive ingredients".

The team found a total of 38 inactive ingredients that have been described in the literature to cause allergic symptoms after oral exposure. Moreover, almost 93 percent of the drugs the researchers studied had at least one of these ingredients.

Drug manufacturers already put warnings on medications that contain refined peanut oil.

Often, formulations of drugs that don't contain these ingredients are available. But some medications, including progesterone, which contains peanut oil, have few alternatives.

Research should also focus on figuring out how often people are actually getting sick from inactive ingredients, particularly in groups like the elderly (who often take more than one drug at a time). They also hope to perform clinical trials to study how much lactose or other common inactive ingredients manifest in symptoms in people who have intolerances to those ingredients. But it turned out that the patient received a formulation of the drug that contained wheat starch as an inactive ingredient, which could lead to an adverse reaction.

The study was published today (March 13) in the journal Science Translational Medicine.

For one, we don't know how often these ingredients are sickening people.

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