title: [Clinical value of estimated half-life in paracetamol poisoning as a complement to Rumack's nomogram].
abstract: OBJECTIVE
  Rumack's nomogram is usually used to indicate the treatment with N-acetilcysteine in the paracetamol poisoning, but it has several limitations. Paracetamol half-life elimination (t1/2) is approximately of 2 h with therapeutic doses and it increases to more than 4 h in patients with hepatotoxicity. The aim of this study was to determine the usefulness of estimated paracetamol t1/2 as greater than or inferior to 4 h by using a simple ratio in relation to the development of hepatotoxicity.
  
  
  METHODS
  21 patients with paracetamol overdose were admitted to Son Dureta Hospital (Palma de Mallorca) and Clínic Hospital (Barcelona) over 13 months. The estimated t1/2 is calculated using the quotient between 2 plasma paracetamol concentrations separated by 2 or more hours.
  
  
  RESULTS
  We found a significant difference (p < 0.005) between the group with hepatotoxicity (n = 3; t1/2 = 8,5 h; range: 3,6 - 8,7 h); and without hepatotoxicity (n = 18; t1/2 = 2,4 h; (range: 1,6 - 4,3 h). We observed an agreement between positive ratio and a t1/2 > 4 h, and negative ratio with t1/2 < 4 h, bearing in mind that the quotient is obtained through mathematical equations.
  
  
  CONCLUSIONS
  Rumack's nomogram should be complemented with t1/2 estimation in all cases of paracetamol poisoning, especially with those patients for whom we are not able to determine the time of ingestion at presentation or if there has been a multiple-timepoint ingestion.
authors.affiliation: Unidad de Toxicología Clínica, Servicio de Análisis Clínicos, Hospital Son Dureta. Palma de Mallorca, Islas Baleares, España. tcastanyer@hsd.es
authors.forename: Bartomeu
authors.initials: B
authors.lastname: Castanyer-Puig
authors.forename: Bernardí
authors.initials: B
authors.lastname: Barceló-Martín
authors.forename: Jordi
authors.initials: J
authors.lastname: Puiguriguer-Ferrando
authors.forename: Marina
authors.initials: M
authors.lastname: Rovira-Illamola
authors.forename: Dolors
authors.initials: D
authors.lastname: Soy-Muner
authors.forename: Santiago
authors.initials: S
authors.lastname: Nogué-Xarau
mesh_terms: D000082:Acetaminophen / Q000378:metabolism* / Q000506:poisoning*; D000328:Adult; D056486:Chemical and Drug Induced Liver Injury / Q000209:etiology* / Q000378:metabolism*; D062787:Drug Overdose; D005260:Female; D006207:Half-Life; D006801:Humans; D008297:Male; D049451:Nomograms; D011237:Predictive Value of Tests
chemical_list: D000082:Acetaminophen