title: Pharmacokinetics and tolerability of anagrelide hydrochloride in young (18 - 50 years) and elderly (≥ 65 years) patients with essential thrombocythemia.
abstract: OBJECTIVE
  To ascertain the role of patient age as an influencing factor in the pharmacokinetics of anagrelide and to clarify whether different dosing is required in young (18 - 50 years) vs. elderly (≥ 65 years) patients with essential thrombocythemia (ET).
  
  
  METHODS
  This Phase II, multicenter, open-label study compared the pharmacokinetics, pharmacodynamics and tolerability of anagrelide and its active metabolite, 3-hydroxy-anagrelide, in young and elderly patients with ET. Three days prior to pharmacokinetic assessment, patients divided their normal daily anagrelide into a structured twice-daily dosing (BID) schedule. Serial blood samples were obtained for pharmacokinetic and pharmacodynamic analysis over a 12-h dosing interval. Anagrelide and 3-hydroxy-anagrelide plasma concentrations were normalized to a common dose (1 mg BID) to control for dosing differences between patients. Patients were monitored routinely for adverse events (AEs) and vital signs.
  
  
  RESULTS
  A total of 24 patients (12 young; 12 elderly) completed the study. The dose-normalized anagrelide maximum observed plasma concentration (Cmax) and area under the plasma concentration vs. time curve over one dosing interval (AUCτ), were higher in elderly patients compared with young patients (Cmax: 3.63 vs. 2.66 ng/ml; p = 0.09, AUCτ: 10.3 vs. 6.4 ng×h/ml; p = 0.01). In contrast, the dose-normalized 3-hydroxy-anagrelide Cmax and AUCτ were lower in the elderly patients when compared with young patients (Cmax: 4.19 vs. 7.26 ng/ml; p = 0.02, AUCτ: 17.4 vs. 27.6 ng×h/ml; p = 0.03). No significant difference was observed in the geometric mean terminal half-life (t1/2) of anagrelide in elderly and young patients (1.4 vs. 1.3 h, respectively; p = 0.38), whereas the geometric mean t1/2 of 3-hydroxy-anagrelide was significantly longer in the elderly patients compared with the young patients (3.5 vs. 2.7 h, respectively; p = 0.01). There were no significant differences in platelet count or vital signs between the age groups. Anagrelide was well tolerated; there were no serious AEs or AEs that led to withdrawal from the study.
  
  
  CONCLUSIONS
  To conclude, the differences observed in anagrelide and 3-hydroxy-anagrelide pharmacokinetics do not justify using a different dosing regimen in young vs. elderly patients with ET.
authors.affiliation: Department of Hematology, Cancer Research Programme, Hospital del Mar-IMIM, Passeig Marítim 25-29, 08003 Barcelona, Spain. cbesses@parcdesalutmar.cat
authors.forename: Carlos
authors.initials: C
authors.lastname: Besses
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Zeller
authors.forename: Alberto
authors.initials: A
authors.lastname: Alvarez-Larrán
authors.forename: Ruth
authors.initials: R
authors.lastname: Coll
authors.forename: Steven
authors.initials: S
authors.lastname: Troy
authors.forename: Jaideep
authors.initials: J
authors.lastname: Purkayastha
authors.forename: Patrick
authors.initials: P
authors.lastname: Martin
authors.forename: Christian
authors.initials: C
authors.lastname: Freitag
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D019540:Area Under Curve; D001711:Biotransformation; D005060:Europe; D005260:Female; D006207:Half-Life; D006401:Hematologic Agents / Q000008:administration & dosage / Q000009:adverse effects / Q000097:blood / Q000493:pharmacokinetics*; D006801:Humans; D006900:Hydroxylation; D008297:Male; D008657:Metabolic Clearance Rate; D008875:Middle Aged; D008954:Models, Biological; D010976:Platelet Count; D011799:Quinazolines / Q000008:administration & dosage / Q000009:adverse effects / Q000097:blood / Q000493:pharmacokinetics*; D013920:Thrombocythemia, Essential / Q000097:blood / Q000175:diagnosis / Q000188:drug therapy*; D034061:Thrombopoiesis / Q000187:drug effects*; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D006401:Hematologic Agents; D011799:Quinazolines; C021139:anagrelide