Splitting Pills May Have Risks

Study Shows Patients Who Split Pills May End Up With Doses That Are Too High or Too Low

Medically Reviewed by Laura J. Martin, MD on January 07, 2011

Jan. 7, 2011 -- Pill splitting, a common practice among many people who are looking to cut medication costs or dosages, is risky business, according to a study in the January issue of the Journal of Advanced Nursing.

Some pills can’t be split 50-50 and there can be a narrow margin between a dose that can help you and one that can hurt you, the researchers report.

“Not all formulations are available for splitting, and even when they are, large dose deviation or weight losses can occur [and] this could have serious clinical consequences for medication with a narrow therapeutic-toxic range,” write researchers who were led by Charlotte Verrue, PharmD, PhD, of Ghent University in Belgium.

In the study, five volunteers split eight different types of pills using a kitchen knife, scissors/hands, or a pill splitter. The participants split the pills into quarters or halves using these three methods. Of the eight types of pills, three had one score down the middle, two had two scores like a cross, and three were unscored. The medications used were for a host of conditions, including Parkinson’s disease, arthritis, and heart disease.

The researchers weighed the tablet and its parts before and after splitting. They found that 31% of the pill slices deviated from their recommended doses by more than 15% and 14% of the pill fragments deviated by more than 25%. Even the most accurate means of pill splitting, the pill splitter, was associated with margins of error.

“We have tested all kinds of tablets: big, small, round, with or without scoring line ... and tried to find an overall method that is best suitable for splitting tablets,” says Verrue in an email to WebMD.  “Dose deviation when splitting tablets is not always a problem. For example, for chronic therapies (e.g. hypertension, etc.) it often doesn't matter when a patient takes a little more of a drug one day and a little less the next day. It becomes problematic when we are talking about bigger dose deviations and drugs that have a narrow therapeutic index (i.e. when a small difference in dosage can have a big difference in effect).”

If you must split your pills, use a splitting device, the researchers conclude.

To Split or Not to Split?

Jeffrey Brewer, PharmD, an associate professor at Albany College of Pharmacy and Health Sciences in New York, says that pill splitting is a widespread practice in the U.S. among people who are trying to get an intermediate dose or to keep their health care costs down.

“The new study puts the downsides of pill splitting into a very specific light,” he says.

In some cases, pill splitting may be a person’s only option due to financial constraints. For example, a 90-day supply could last for six months if the pills are split.

A half or a quarter of a pill may be better than nothing, but this varies based on the type of medication and its dosing formulation.

“Different tablets split differently,” he says. “Some crumble, others are hard and cut very clean. Some tablets are coated, others are long acting or short acting, and some are capsules or extended release,” he says. “Others are scored down the middle and can be broken with your thumbs, and a lot don't have any scores at all.”

There is no clear-cut consensus on which pills you can, or can’t, split, he says.

“It would be unsafe to say ‘yes you could do this with three out of five of your pills or all of your medications,’” he says. “You need to evaluate how well your disease is controlled, why you are splitting, and what tablets you want to split.”

Pills are split all the time, and some insurers even offer incentives to get their members to cut their pills, says Alan M. Weiss, MD, an internal medicine doctor at the Cleveland Clinic in Ohio. “It can be a great cost-saving mechanism for patients who can do it and do it on the right pills.”

"There are some pills where you can break the seal if you cut them, and this can cause the medication to degrade,” he says.

Extended Release, Coated Pills Can’t Be Split

“If want to split a pill, there are a lot that are already scored and are designed to be cut,” he says.

“Extended-release tablets and capsules can’t be cut.”

Yuly Belchikov, PharmD, an assistant director for clinical pharmacy services and education at Long Island Jewish Medical Center, New Hyde Park, N.Y., says that pill splitting can be a problem for pills with a small therapeutic window. This refers to a pill that needs to be taken in very controlled, precise doses.

“Pill-splitting a medication with a small therapeutic window is concerning because any deviation from the recommended dose, even a small percentage, can have serious consequences,” he says.

Papatya Tankut, PharmD, vice president of pharmacy professional services at CVS Caremark in Woonstocket, R.I., sums it up this way: “Ask a pharmacist or a physician before you split any pill. Don’t decide to do it on your own because there are some toxic effects of splitting pills that weren’t designed to be split.”

“Use a pill-splitting device so you are accurately splitting the dose,” she says, and split pills only on an as-needed basis. “Air or moisture can change the formulation and deem it less effective when you do it in advance.”

Show Sources


Papatya Tankut, PharmD, vice president, pharmacy professional services, CVS Caremark, Woonstocket, R.I.

Jeffrey Brewer, PharmD, associate professor, Albany College of Pharmacy and Health Sciences, N.Y.

Yuly Belchikov, PharmD, assistant director, clinical pharmacy services and education, Long Island Jewish Medical Center, New Hyde Park, N.Y.

Alan M. Weiss, MD, internal medicine physician, Cleveland Clinic, Ohio.

Verrue, C. Journal of Advanced Nursing, 2010.

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