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Tablet splitting: Do it only if you "half" to, and then do it safely

From the May 18, 2006 issue

Problem: Most oral medications are available commercially in the dosage strengths most commonly prescribed for patients. Occasionally, the patient’s exact dose is not available commercially, so more than one tablet or just part of a tablet may be needed.  While using more than one tablet for a single dose is customary, tablet splitting has become more commonplace in the past 5 years for several reasons: 

  • Different tablet strengths often cost about the same. Patients who cannot afford their medications have received a higher strength tablet with directions to take ½ tablet (or even ¼ tablet) per dose (1).
  • Some health insurers have denied payment of prescriptions for the lower strength of certain drugs, thus requiring patients to receive the higher strength tablet and split it in half for each dose (1).
  • Some healthcare organizations have not purchased all commercially available strengths of oral medications. Thus, some of the drugs may require tablet splitting for patient-specific doses in the inpatient setting. 
  • Patients may not be able to swallow whole tablets (2).

A recent article in the Veterans Administration (VA) Topics in Patient Safety newsletter (2) and a 2002 article on the American Society of Consultant Pharmacists website, Tablet Splitting for Cost Containment, authored by Thomas Clark (1), offer several pitfalls with splitting tablets that clearly suggest it is not the safest option if the patient-specific dose is available commercially.

Patient factors. First, it is easy for patients to become confused about the correct dose. One woman learned this when she was admitted to the hospital with unstable angina and hypertension. Her physician found that she had been taking the wrong dose of lisinopril. She was supposed to be taking 5 mg BID, but the prescription label said there were 10 mg tablets in the bottle. When the physician looked inside, he saw both pink and peach tablets, some of which were split in half. Initially, the patient had been taking a 20 mg tablet BID. When her physician lowered the dose to 10 mg BID, she had the new prescription filled. The patient then cut the leftover 20 mg tablets in half and put them in the same bottle that held the 10 mg tablets. Later, her physician lowered the dose to 5 mg BID. Instead of filling the new prescription for 5 mg tablets, she tried to find all the 10 mg tablets to split them in half, but some remained whole. 

In this case, no one could be certain of the dose the patient had been taking before she was hospitalized. But a study by the VA showed that most people took too much medication because they forgot to split their tablets (2). Between January 2001 and April 2005, the VA’s National Center for Patient Safety database included 442 reports related to pill splitting. Of those, 38% were considered adverse events, mostly occurring in outpatient settings (65%). Two-thirds of the patients received more than the intended dose. Pharmacists caught these errors because the patients came in too soon to refill their prescriptions. A quarter of the medications were high-alert drugs. About 9% of patients were harmed by these mistakes; 2% required hospitalization. In more than half of the events, the involved doses were available commercially.

Clark identified a few additional risks with tablet splitting (1):

  • A pharmacist might misread a prescription written for 1/2 tablet as 1-2 tablets.
  • Patients may assume the tablets have already been split when they have not, or split them again when they have been split already (especially if the pharmacy inconsistently splits the tablets upon refill).
  • Patients may not have the visual acuity or manual dexterity needed to split the tablets.
  • Patients may get confused and split the wrong medication, or get tired of splitting the tablets and stop taking it.
  • To maximize cost savings, the patient may have been told to split the tablets in half, but the directions on the prescription may list “1 tablet” for each dose. These directions could mislead the patient or other healthcare providers who use the prescription label as a source of information when gathering a patient's medication history.     
  • Split tablets crumble more easily. 

Medication factors. Some medications or formulations are not suitable for splitting, including:

  • Enteric-coated/extended-release tablets
  • Very small tablets
  • Asymmetrical tablets
  • Capsules
  • Teratogenic medications (e.g., bosentan).

Clark cites various studies that suggest that the accuracy of split tablets is questionable, even if the tablet is scored.1 In one study, 94 volunteers were asked to split 10 tablets of hydrochlorothiazide 25 mg; 41% of the split tablets deviated by 10% of the correct weight, and 12% deviated by more than 20%. After the study, two-thirds of the volunteers said they would be willing to pay more for commercially available tablets in the correct strength. Other research cited by Clark corroborates the significant variation in tablet halves with rates of inaccuracy ranging from 5-72%.

Safe Practice Recommendations: Healthcare providers should make every effort to use commercially available oral tablets when available in both inpatient and outpatient settings. However, tablet splitting may still be necessary if the drug is not commercially available in the patient-specific dose, or if the patient’s inability to afford the medication as an outpatient outweighs the risks involved with tablet splitting. Under these circumstances, consider the following suggestions from Clark, the VA, and ISMP:

Verify suitability. Before prescribing, dispensing, or administering half tablets, check drug references to ensure that it is safe. If unsure, contact the manufacturer.2 
Select patients carefully. Establish criteria to screen patients before prescribing or dispensing half tablets to ensure they have the required level of understanding, ability, and motivation to split the tablets (1,2). Ensure that the patient understands the risks associated with tablet splitting. If the patient cannot be expected to split his or her own tablets, enlist the aid of a qualified family member. (Note: It may not be legal in some states for a pharmacist to split tablets if the dose is available commercially [1]).

Dispense split tablets for inpatients. For hospitalized patients, pharmacy staff should dispense exact doses by either splitting tablets and repackaging them or preparing an oral solution in a unit-dose oral syringe for each dose. Nurses should not be expected to split the tablets.   

Keep it clean. Patients and healthcare providers who split tablets should wash their hands first. Healthcare providers should also wear gloves. If a tablet-splitting device is used, it should be washed afterwards to remove any powder or particles. 

Prescribe by weight. Prescribers should order the medication strength and dose in “mg” when possible to avoid misreading an order for a “1/2” tablet as 1-2 tablets.

Counsel patients. Establish a system to ensure patient counseling when prescriptions for medications that require half tablets are picked up at community pharmacies, even if the pharmacist has split the tablets for the patient (2). 

Provide the right tools. If patients must split tablets at home, provide them with a tablet- splitting device to improve the accuracy (2). 

Provide discharge education. If patients are receiving half tablets while in the hospital, advise them regarding the dose they should take after discharge and whether this requires split or whole tablets.

References: 1) Clark TR. Tablet splitting for cost containment. August 2002. Available at: 2) Sales MM, Cunningham FE. Tablet splitting. Veterans Administration Topics in Patient Safety (TIPS). 2006;6(3):1,4.

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