title: Population pharmacokinetics of aprepitant and dexamethasone in the prevention of chemotherapy-induced nausea and vomiting.
abstract: OBJECTIVE
  To develop a population pharmacokinetic model of aprepitant and dexamethasone in Japanese patients with cancer, explore the factors that affect the pharmacokinetics of aprepitant, and evaluate the effect of aprepitant on the clearance of intravenous dexamethasone.
  
  
  METHODS
  A total of 897 aprepitant concentration measurements were obtained from 290 cancer patients and 25 healthy volunteers. For dexamethasone, a total of 847 measurements were obtained from 440 patients who were co-administered aprepitant (40, 125 mg, or placebo). Plasma concentration of aprepitant and dexamethasone were determined by liquid chromatography connected with a tandem mass spectrometer and analyzed by a population approach using NONMEM software.
  
  
  RESULTS
  The plasma concentration time course of aprepitant was described using a one-compartment model with first-order absorption and lag time. Oral clearance (CL/F) of aprepitant was changed by aprepitant dose at doses of 40 or 125 mg. Body weight was the most influential intrinsic factor to CL/F of aprepitant. Age, ALT, and BUN also had mild effects on the CL/F. Typical population estimates of CL/F, apparent distribution volume (V(d)/F), absorption constant (K(a)) and absorption lag time were 1.54 L/h, 72.1 L, 0.893/h and 0.295 h, respectively. Inter-individual variability in CL/F, V(d)/F and K(a) were 53.9, 21.0, and 141%, respectively; intra-individual variability was 27.7%. The plasma concentration time course of intravenous dexamethasone was also described using a one-compartment model. Clearance of dexamethasone was decreased 24.7 and 47.5% by co-administration of aprepitant 40 and 125 mg. All final model estimates of aprepitant and dexamethasone fell within 10% of the bootstrapped mean.
  
  
  CONCLUSIONS
  A pharmacokinetic model for aprepitant has been developed that incorporates body weight, age, ALT, BUN and aprepitant dose to predict the CL/F. The results of population pharmacokinetic analysis of dexamethasone support dose adjustment of dexamethasone in the case of co-administration with aprepitant.
authors.affiliation: Pharmacokinetic Research Laboratories, Ono Pharmaceutical Co, Ltd, Tsukuba, Ibaraki, Japan. s.nakade@ono.co.jp
authors.forename: Susumu
authors.initials: S
authors.lastname: Nakade
authors.forename: Tomoya
authors.initials: T
authors.lastname: Ohno
authors.forename: Junsaku
authors.initials: J
authors.lastname: Kitagawa
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Hashimoto
authors.forename: Masahiro
authors.initials: M
authors.lastname: Katayama
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Awata
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Kodama
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Miyata
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000932:Antiemetics / Q000097:blood / Q000493:pharmacokinetics* / Q000627:therapeutic use; D000970:Antineoplastic Agents / Q000009:adverse effects*; D000077608:Aprepitant; D001682:Biological Availability; D003907:Dexamethasone / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics* / Q000627:therapeutic use; D004359:Drug Therapy, Combination; D005260:Female; D017829:Granisetron / Q000008:administration & dosage / Q000627:therapeutic use; D006801:Humans; D007262:Infusions, Intravenous; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D009025:Morpholines / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics* / Q000627:therapeutic use; D009325:Nausea / Q000139:chemically induced / Q000517:prevention & control*; D014839:Vomiting / Q000139:chemically induced / Q000517:prevention & control*
chemical_list: D000932:Antiemetics; D000970:Antineoplastic Agents; D000077608:Aprepitant; D003907:Dexamethasone; D017829:Granisetron; D009025:Morpholines