Most common medications prescribed by family doctors contain animal products, but it’s hard to tell if they’re suitable for vegetarians and other patients with dietary preferences, a new study finds.

Many patients and doctors are unaware that commonly prescribed drugs contain animal products, which isn't clear by reading the list of ingredients, researchers say in this week’s issue of the British Medical Journal.

Cda Drug Shortages 20120308

Most of the commonly prescribed drugs in the U.K. contain ingredients from animal products that doctors and patients may be unaware of, researchers found. (Jacques Boissinot/Canadian Press)

Dr. Kinesh Patel, a research fellow at St. Mark’s Hospital in Harrow and Dr. Kate Tatham of Imperial College in London, said the potential "problem ingredients" include:

  • Gelatine, which is widely used to encapsulate medications and is sourced from cows, pigs and occasionally fish. If derived from pigs it can be a problem for some Jews and Muslims.
  • Lactose, traditionally extracted using bovine rennet, is used as a filler and in manufacturing medications.
  • Magnesium stearate, a lubricant, which is traditionally sourced from cows, pigs and sheep. Some manufacturers now use vegetarian alternatives.

The researchers said that last year, a campaign to vaccinate children against flu in Scotland was stopped because of concerns in the Muslim community about pork gelatine in the vaccine, despite assurances. They said that in 1995, the World Health Organization’s seminar of religious scholars concluded that gelatine transformed from impure bones is pure and ingesting such products is permitted.

To determine the scale of the problem, the researchers checked into the 100 most commonly prescribed drugs in U.K. primary care practices. Of these, 73 contained one or more of lactose, gelatine, or magnesium stearate. That was the easy part.

Then they tried to source the type of animal by contacting manufacturers.

"We found it was difficult to determine the suitability of common drugs for patients with specific dietary preference," the pair wrote.

"It is unlikely that any labelling standard could address all dietary requirements, and the ultimate solution would be to eliminate animal derived products where possible from medications."

Lactose is already produced by some manufacturers without using rennet, magnesium stearate can be made chemically without animal ingredients, and vegetarian capsules to replace gelatine are available. The researchers said costs are likely to fall as production expands.