Dangers of pill splitting?

Craig asks: 

A lot of data sheets I have seen for medicines in tablet form say something along the lines of “Do not halve the tablet. Dose equivalence when the tablet is divided has not been established.”

How accurate is this statement? Would dividing tablets with this warning be acceptable in a TEOTWAWKI situation?

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As author of 101 Ways to Save Money on Health Care, I frequently recommend pill-splitting as a cost-saving measure.  For TEOTWAWKI purposes, it is reasonable to stock higher doses of certain medications, with the thought of possibly splitting them later if needed.  Higher dosage forms often cost the same as lower dosages, and may take up little additional space.

Unless a tablet is scored, the manufacturer does not intend it to be split, and studies on dose equivalency on divided tablets are unlikely to have been performed. Much of the time, however, this does not matter.

The biggest concern with pill-splitting is extended-release medications.  There are numerous ways to alter the delivery system of a drug with a short half-life, making it possible to administer the medicine once or twice daily instead of three or four.  Often the mechanism lies in the tablet coating.  If this is disrupted, the long-acting pill will “revert” to a short-acting pill, by disabling the delivery system.  Some long-acting pills may be split, however, when the delivery system is built into the micro-structure of the pill rather than the macro-structure.  An example of this is certain verapamil formulations.

An example of how pill-splitting may be harmful is extended-release beta-blockers, which if split may allow the entire dose to be “dumped” into the circulation rapidly, resulting in cyclic low blood pressure and/or slow heart rate, alternating with high blood pressure and/or rapid heart rate before the next dose is given.  Steady-state levels and consistent BP lowering are preferable.

However, for many medications pill-splitting causes no discernable harm. For example, with Synthroid (levothyroxine) doctors aim at a specific dose, say 100 mcg per day.  Splitting a 200-mcg tablet may result in a dose of 95 mcg one day and 105 the next (or even losing several mcg as pill-dust) but over the long run this evens out.  With the bioavailability of generic drugs varying as much as +/- 20%, a little inaccuracy in pill-splitting causes similar variability, with little if any detrimental effect.

The same holds true for antibiotics, many pain pills, anti-inflammatories, cold medicines, diabetic pills, anti-depressants, cholesterol pills, and many more.   For conditions or medications where blood levels are critical, pill-splitting may be inadvisable, although even warfarin is often split for adjustable dosing. 

Another concern of pill-splitting is structural stability.  Once a pill is split, it is more easily subject to physical trauma, as well as effects of humidity and heat.  Storing pills whole is advisable, with splitting done shortly before use.

Regarding capsules, although these cannot be split, some can be opened and the contents evenly divided.  This question arises most frequently with expensive medications such as Prevacid, a capsule which may be opened and sprinkled on food.

In summary, while the statement Craig references is true, it has little clinical relevance for many conditions.  However, before resorting to pill-splitting, ask your doctor or pharmacist if he or she has any particular concerns.  “By-the-book” professionals may be against the practice, but still should be able to give you an answer for what is likely to occur if you do split a particular pill. 

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About Cynthia J. Koelker, MD

CYNTHIA J KOELKER , MD is a board-certified family physician with over twenty years of clinical experience. A member of American Mensa, Dr. Koelker holds degrees in biology, humanities, medicine, and music from M.I.T., Case Western Reserve University School of Medicine, and the University of Akron. She served in the National Health Service Corps to finance her medical education.
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