title: A New Method for Individualized Digoxin Dosing in Elderly Patients.
abstract: BACKGROUND
  Digoxin is a frequently prescribed drug in the elderly population. Estimated glomerular filtration rate is widely used to adjust dosages. The HUGE value is a tool for differentiating the presence or absence of chronic kidney disease in elderly patients. We aimed to investigate the usefulness of the HUGE value to predict the initial dose of digoxin in patients aged older than 70 years.
  
  
  METHODS
  We reviewed retrospectively the medical records of patients aged older than 70 years with serum digoxin concentrations (SDCs) monitored over a 6-month period (63 patients). A linear regression relating the patient's SDC, maintenance dose of digoxin and the HUGE value was estimated to generate a dosage equation. This equation was validated retrospectively (33 patients) and prospectively (35 patients) in comparison with two existing methods based on creatinine clearance.
  
  
  RESULTS
  An equation (HUGE_DIG) was generated to calculate the initial digoxin dose to reach a specific target SDC. Thus, to achieve a SDC of 0.8 ng/mL: Digoxin (mg/day) = 0.091 - 0.006 x HUGE. After retrospective validation, the calculated digoxin doses with this equation were administered in the prospective phase and we did not observe statistical differences between measured and desired SDCs. Moreover, the predictive performance of our equation was better than that obtained with the compared methods.
  
  
  CONCLUSIONS
  We offer a new validated digoxin dosing equation for elderly patients. Our results support the need to perform digoxin dosing in elderly people, bearing in mind the changes in renal physiology secondary to ageing and not merely the estimated glomerular filtration rate.
authors.affiliation: Department of Pharmacy and Pharmaceutical Technology, Faculty of Pharmacy, University of Salamanca, Salamanca, Spain.|Instituto de Investigación Biomédica de Salamanca, University Hospital of Salamanca, Salamanca, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Martin-Suarez
authors.affiliation: Pharmacy Services, University Hospital of Salamanca, Salamanca, Spain.
authors.forename: David
authors.initials: D
authors.lastname: García González
authors.affiliation: Nefrology Services, University Hospital of Salamanca, Salamanca, Spain.|Instituto de Investigación Biomédica de Salamanca, University Hospital of Salamanca, Salamanca, Spain.
authors.forename: Juan F
authors.initials: JF
authors.lastname: Macías Núñez
authors.affiliation: Department of Statistics, Faculty of Sciences, University of Salamanca, Salamanca, Spain.
authors.forename: Ramón
authors.initials: R
authors.lastname: Ardanuy Albajar
authors.affiliation: Department of Pharmacy and Pharmaceutical Technology, Faculty of Pharmacy, University of Salamanca, Salamanca, Spain. toyi@usal.es.|Pharmacy Services, University Hospital of Salamanca, Salamanca, Spain. toyi@usal.es.|Instituto de Investigación Biomédica de Salamanca, University Hospital of Salamanca, Salamanca, Spain. toyi@usal.es.
authors.forename: M Victoria
authors.initials: MV
authors.lastname: Calvo Hernández
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D000465:Algorithms; D004077:Digoxin / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D007677:Kidney Function Tests; D008297:Male; D012189:Retrospective Studies
chemical_list: D004077:Digoxin
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