title: Chronopharmacology of granulocyte colony-stimulating factor in mice.
abstract: The role of the sensitivity of bone marrow cells to, and the pharmacokinetics of granulocyte colony-stimulating factor (G-CSF) on the rhythm of leukocyte-increasing effect was investigated in ICR male mice housed under a standardized light-dark cycle (lights on at 0700, off at 1900). A significant circadian rhythm was demonstrated for leukocyte counts at 24 hr after G-CSF (250 microg/kg, s.c.) injection at six different circadian times (P < .01). The leukocyte counts of mice given G-CSF at 0500, 0900, 1300 or 1700 were significantly higher than those of mice given G-CSF at 2100 (P < .01, respectively). The rhythmic pattern resembled overall the rhythm occurring after saline injection. In the comparison between leukocyte counts after G-CSF injection at 0700 and 1900, the time when leukocyte counts are equal in nondrugged state, the leukocyte counts at 24 hr after G-CSF (250 microg/kg, i.v.) injection were approximately 50% higher in mice injected with the drug at 0700 than at 1900 (P < .01). Bone marrow cultures obtained at two times of day resulted in different numbers of myeloid colonies even when treated with the same concentrations of G-CSF in vitro. The colony-forming activity of G-CSF was significantly more potent at 0700 than at 1900 (P < .01). The plasma G-CSF concentrations after G-CSF (250 or 5 microg/kg, i.v.) injection were significantly higher in mice receiving injections with the drug at 0700 than at 1900 (P < .05, respectively). The area under the curve and mean residence time were significantly larger in mice injected with the drug at 0700 than at 1900 (P < .01, P < .05, respectively). Our suggests that the rhythm of G-CSF activity is caused by that of the sensitivity of bone marrow cells to, and the pharmacokinetics of the drug.
authors.affiliation: Department of Clinical Pharmacokinetics, Division of Pharmaceutical Science, Kyushu University, 3-1-1, Maidashi, Higashi-Ku, Fukuoka, 812 Japan.
authors.forename: S
authors.initials: S
authors.lastname: Ohdo
authors.forename: N
authors.initials: N
authors.lastname: Arata
authors.forename: T
authors.initials: T
authors.lastname: Furukubo
authors.forename: E
authors.initials: E
authors.lastname: Yukawa
authors.forename: S
authors.initials: S
authors.lastname: Higuchi
authors.forename: S
authors.initials: S
authors.lastname: Nakano
authors.forename: N
authors.initials: N
authors.lastname: Ogawa
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000187:drug effects / Q000378:metabolism; D002940:Circadian Rhythm / Q000187:drug effects; D003114:Colony-Forming Units Assay; D004305:Dose-Response Relationship, Drug; D016179:Granulocyte Colony-Stimulating Factor / Q000008:administration & dosage / Q000378:metabolism / Q000493:pharmacokinetics / Q000494:pharmacology*; D007958:Leukocyte Count / Q000187:drug effects*; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR
chemical_list: D016179:Granulocyte Colony-Stimulating Factor