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Pill Splitting Leads To Rhabdomyolysis & Renal Failure
Patient compliance is always a tricky issue, but adding a complicated dosing regimen to the mix—such as pill splitting—can compound the problem, setting the stage for legal trouble. The following is an active case illustrating the potential for medication errors with pill splitting.
A 59-year-old man who had undergone heart transplant was prescribed simvastatin (Zocor, Merck) at a dose of 20 mg. He was also taking mycophenolate mofetil capsules (CellCept, Roche) 1,500 mg b.i.d., prednisone 7.5 mg qd, amlodipine (Norvasc, Pfizer) 10 mg qd, lansoprazole capsules (Prevacid, TAP) 30 mg qd, calcium carbonate 1,000 mg t.i.d., multivitamins 2 tablets qd, magnesium oxide (Mag-Ox, Blaine) 400 mg b.i.d., acetylsalicylic acid (aspirin) 325 mg qd, and cyclosporine capsules (Neoral, Novartis) 150 mg b.i.d. His cholesterol was slightly elevated (208 mg/dL), so the nurse practitioner increased his prescription for simvastatin from 20 mg to 40 mg at bedtime.
When the patient took his simvastatin prescription to the pharmacy, the pharmacist filled it with an 80-mg tablet, with instructions for the patient to take one “half tablet at bedtime.” The pharmacist did not contact the prescriber or the patient’s clinic to divulge this information.
Six months later, the patient’s cholesterol had risen slightly. He explained to the nurse practitioner that he was taking “half a tablet”. She noted that the patient had previously been prescribed a 40-mg tablet and, thus, she assumed that he was taking 20 mg simvastatin as the half-tablet. The nurse practitioner told the patient to take “a whole tablet” from then on with the belief that he would then be taking 40 mg at bedtime. In actuality, the patient was now taking 80 mg per day—double the dose intended by the prescriber.
A few weeks later, the patient began to experience leg pain and was hospitalized. Physicians discovered that he had developed rhabdomyolysis, a serious muscle disease that can cause kidney failure. Fortunately, the patient survived the ensuing renal failure. The simvastatin was discontinued.
When confronted with the facts, the nurse practitioner and the lawyers for the clinic blamed the pharmacist for changing the prescription from a 40-mg tablet to one-half of an 80-mg tablet. They contended that the overdose, which led to the rhabdomyolysis, would not have occurred if the pharmacist had advised the nurse practitioner and the clinic of the dosage shift.
The lawyers for the pharmacy (a managed care pharmacy group) defended the pill splitting, stating that it was a routine, cost-effective practice. The pharmacy denied any wrongdoing in the matter. |
Costs Versus Benefits of Pill Splitting
A brief scan through the Physicians’ Desk Reference (2003) pictorial product identification pages shows dozens of scored tablets, which are designed to be split. A review of the oral solid dosage form chapter in the 20th edition of Remington’s Practice of Pharmacy (Philadelphia, Pa: Lippincott; 2003) has no discussion of tablet scoring.
A search of PubMed produces a dozen articles that mention pill splitting in the title or the abstract. Topics range from the projection of substantial cost savings to cautionary tales of pill splitting. For example, Rosenberg, et al. (2005) tested weight variations in tablet fragments resulting from pill splitting and found that the practice resulted in an unacceptably high incidence of weight variation. The authors recommended that standards should be developed to ensure uniformity of split tablets. |
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In a recent study assessing the potential savings of splitting newer antidepressants, Cohen and Cohen (2002) found that the pricing structure of these medications is largely independent of pill strength. Their analysis showed that splitting higher-strength pills may nearly halve the average cost per dose. As they explained, 42% of antidepressants available in 2000 were at strengths that permitted splitting and were not in capsular or time-release forms. “If all eligible prescriptions had utilized split doses, purchasers could have saved over [$1.7 billion],” the authors concluded. The authors caution that pill splitting may be inadvisable for certain subgroups of patients, such as those with reduced cognition, sensory or motor impairment or older persons on polypharmacy.
In a recent study, Polli and colleagues from the Veterans Affairs Maryland Healthcare System measured the weight conformity of split tablets (2003). Of 12 medications commonly split, four failed the weight-uniformity test. Simvastatin was among the medications that failed this test.
Learning Points
We cannot really debate the issue of whether to split or not to split pills in this column. The evidence of potential cost savings is compelling, and the design of tablets—assuming that they are not sustained-release—usually includes scoring. This case is about communication. The prescriber did not know that the pharmacy was changing the prescription to take advantage of pill splitting. The nurse practitioner assumed that the patient was taking a certain dose, without examining the prescription bottle and without calling the pharmacy to verify what dose he was taking.
References
Cohen CI and Cohen SI: Potential savings from splitting newer antidepressant medications.[see comment]. Comment in: CNS Drugs. 2002;16(5):359-60. CNS Drugs. 16(5):353-8, 2002.
Physicians Desk Reference, Thompson Publishing Montvale, NJ: 2003
Polli JE, Kim S, and Martin BR: Weight uniformity of split tablets required by a Veterans Affairs policy. Journal of Managed Care Pharmacy. 9(5):401-7, 2003 Sep-Oct.
Remington’s Practice of Pharmacy. 2003. Lippincott. Philadelphia, Pa
Rosenberg JM, Nathan JP, and Plakogiannis F: Weight variability of pharmacist-dispensed split tablets.[see comment]. Comment in: J Am Pharm Assoc (Wash). 2002 Mar-Apr;42(2):160-2. Journal of the American Pharmaceutical Association. 42(2):200-5, 2002 Mar-Apr.
Scott SA. The Prescriptin. Chapter 97, In Gennaro AR, Ed.Philadelphia, Pa: Lippincott; 2003
The original version of this article was printed in Pharmacy Practice News.
Dr. O’Donnell is a pharmacologist and pharmacist, with over 20 years of hospital experience. He is a nationally recognized speaker, is widely published, and maintains a busy consulting practice. |
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 By James T. O’Donnell, PharmD, MS, FCP
Jodonn1935@aol.com | |
