title: Usefulness of the simultaneous determination of serum levels of theophylline and its metabolites in patients medicated with theophylline preparation.
abstract: OBJECTIVE
  Measurement of the serum level of theophylline is essential for its proper use; however, it is difficult to infer the metabolic ability of individual patients by only the serum theophylline level and to decide the appropriate medication. In this study, we simultaneously measured serum theophylline and metabolite levels in patients treated with theophylline, and investigated their usefulness.
  
  
  METHODS
  The subjects were asthma patients who visited the outpatient clinic of Respiratory Medicine, St Luke's International Hospital, between April and October 2003, and were medicated with sustained-release theophylline tablets (Theodur®). The serum level of theophylline and its metabolites was measured by HPLC in patients who gave written consent.
  
  
  RESULTS
  A strong correlation was noted between the serum theophylline (TP) and 1,3-dimethyluric acid (DMU) levels of 52 patients (r = 0.670), and DMU/TP was about 0.04. In a patient whose the DMU/TP was 0.216, it was recognized that metabolic ability was promoted due to a history of smoking.
  
  
  CONCLUSIONS
  In this study, it was shown that simultaneous measurement by HPLC of the serum level of theophylline and its metabolites and DMU/TP was useful to assess the metabolic ability of individual patients.
authors.affiliation: Department of Pharmacy, Saiseikai Yokohamashi Nanbu Hospital, 3-2-10 Kounandai, Kounan-ku, Yokohama-shi, Kanagawa, Japan. yuko_3u@yahoo.co.jp
authors.forename: Yuko
authors.initials: Y
authors.lastname: Watanabe
authors.forename: Naohiko
authors.initials: N
authors.lastname: Chohnabayashi
authors.forename: Hideki
authors.initials: H
authors.lastname: Nasu
authors.forename: Naoki
authors.initials: N
authors.lastname: Nishimura
authors.forename: Noboru
authors.initials: N
authors.lastname: Uchiyama
authors.forename: Junko
authors.initials: J
authors.lastname: Kizu
mesh_terms: D001249:Asthma / Q000097:blood / Q000188:drug therapy; D001993:Bronchodilator Agents / Q000008:administration & dosage* / Q000097:blood*; D002110:Caffeine / Q000097:blood; D002851:Chromatography, High Pressure Liquid; D006801:Humans; D012907:Smoking / Q000097:blood; D013806:Theophylline / Q000008:administration & dosage* / Q000097:blood*; D014527:Uric Acid / Q000031:analogs & derivatives / Q000097:blood
chemical_list: D001993:Bronchodilator Agents; D014527:Uric Acid; D002110:Caffeine; D013806:Theophylline; C031274:1,3-dimethyluric acid