TUESDAY, Feb. 28 (HealthDay News) -- Vegetarians and others who avoid eating meat for religious or cultural reasons may unknowingly be consuming gelatin derived from animal products when they take prescription medications, a new study found.

Animal-derived gelatin is a commonly used coating agent in medications, and it is also used as a thickener in some liquid and semisolid drugs.

The gelatin is contained in ingredients known as excipients -- inactive substances such as sweeteners, fillers and lubricants -- which typically are not listed on a drug's label. The researchers, from Manchester Royal Infirmary in England, said more comprehensive labeling and vegetarian alternatives to drug ingredients are needed.

In the study, which was published online in the Postgraduate Medical Journal, researchers surveyed 500 patients in Manchester being treated for urological disorders. Participants were asked about their dietary preferences and their willingness to take medications they knew contained ingredients made from animals. Many were from ethnic minorities.

Of the 500 patients surveyed, more than half were taking medication for their condition, and 200 said they were not supposed to eat animal products. Of those subjects with restricted diets, 88 percent said they would prefer not to take drugs that contained ingredients derived from animals.

Of the subjects who said they would rather not take drugs containing animal products, 57 percent said they would take the medicine anyway if no alternative were available, while 43 percent said they would not.

Only one in five, however, said they would ask their doctor or pharmacist if the medication they were prescribed contained animal products. The researchers view these findings as potentially posing ethical quandaries for the entire profession.

"We already know that doctors are fairly ignorant about the issue of excipients in medication," the researchers said in a news release from the journal.

They also said this problem is not limited to drugs used to treat urological conditions.

"[Gelatin content] is almost certainly a much bigger issue for the 860 million non-urological preparations prescribed in the U.K. each year, whose excipient content is not easily identified," the researchers cautioned.

More information

The U.S. National Institutes of Health provides more information on vegetarian diets.