title: Tablet splitting of narrow therapeutic index drugs: a nationwide survey in Taiwan.
abstract: BACKGROUND
  Tablet splitting or pill splitting frequently occurs in daily medical practice. For drugs with special pharmacokinetic characters, such as drugs with narrow therapeutic index (NTI), unequal split tablets might lead to erroneous dose titration and it even cause toxicity.
  
  
  OBJECTIVE
  The aim of this study was to investigate the frequency of prescribing split NTI drugs at ambulatory setting in Taiwan.
  
  
  METHODS
  A population-based retrospective study was conducted using the National Health Insurance Research Database in Taiwan. All ambulatory visits were analyzed from the longitudinal cohort datasets of the National Health Insurance Research Database.
  
  
  METHODS
  The details of ambulatory prescriptions containing NTI drugs were extracted by using the claims datasets of one million beneficiaries from National Healthcare Insurance Research Database in 2010 in Taiwan. The analyses were stratified by dosage form, patient age and the number of prescribed tablets in a single dose for each NTI drugs. Main outcome measures Number and distinct dosage forms of available NTI drug items in Taiwan, number of prescriptions involved split NTI drugs, and number of patients received split NTI drugs.
  
  
  RESULTS
  A total of 148,548 patients had received 512,398 prescriptions of NTI drugs and 41.8 % (n = 62,121) of patients had received 36.3 % (n = 185,936) of NTI drug prescriptions in form of split tablets. The percentage of splitting was highest in digoxin prescriptions (81.0 %), followed by warfarin (72.0 %). In the elderly patients, split tablets were very prevalent with digoxin (82.4 %) and warfarin (84.5 %).
  
  
  CONCLUSIONS
  NTI drugs were frequently prescribed to be taken in split forms in Taiwan. Interventions may be needed to provide effective and convenient NTI drug use. Further studies are needed to evaluate the clinical outcome of inappropriate split NTI drugs.
authors.affiliation: Department of Pharmacy, Taipei Veterans General Hospital, No. 201, Sec. 2, Shi-Pai Road, Taipei, Taiwan, ROC.
authors.forename: Chia-Lin
authors.initials: CL
authors.lastname: Chou
authors.affiliation: Department of Pharmacy, Taipei Veterans General Hospital, No. 201, Sec. 2, Shi-Pai Road, Taipei, Taiwan, ROC.
authors.forename: Chia-Chen
authors.initials: CC
authors.lastname: Hsu
authors.affiliation: Department of Critical Care Medicine, Taipei Veterans General Hospital, Taipei, Taiwan, ROC.|Department of Medicine, Tzu Chi University, Hualian, Taiwan, ROC.
authors.forename: Chia-Yu
authors.initials: CY
authors.lastname: Chou
authors.affiliation: Institute of Hospital and Health Care Administration, School of Medicine, National Yang-Ming University, Taipei, Taiwan, ROC.|Department of Family Medicine, Taipei Veterans General Hospital, Taipei, Taiwan, ROC.
authors.forename: Tzeng-Ji
authors.initials: TJ
authors.lastname: Chen
authors.affiliation: Department of Public Finance, National Chengchi University, Taipei, Taiwan, ROC.
authors.forename: Li-Fang
authors.initials: LF
authors.lastname: Chou
authors.affiliation: Department of Pharmacy, Taipei Veterans General Hospital, No. 201, Sec. 2, Shi-Pai Road, Taipei, Taiwan, ROC. ycchou@vghtpe.gov.tw.|Department and Institute of Pharmacology, National Yang-Ming University, Taipei, Taiwan, ROC. ycchou@vghtpe.gov.tw.|School of Pharmacy, Taipei Medical University, Taipei, Taiwan, ROC. ycchou@vghtpe.gov.tw.
authors.forename: Yueh-Ching
authors.initials: YC
authors.lastname: Chou
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009313:National Health Programs / Q000706:statistics & numerical data*; D055553:Prescription Drugs / Q000008:administration & dosage*; D015995:Prevalence; D012189:Retrospective Studies; D013607:Tablets / Q000008:administration & dosage*; D013624:Taiwan; D055815:Young Adult
chemical_list: D055553:Prescription Drugs; D013607:Tablets
keywords: Narrow therapeutic index drugs; Prescribing patterns; Splitting frequency; Tablet splitting; Taiwan