title: Multiple-dose FTY720: tolerability, pharmacokinetics, and lymphocyte responses in healthy subjects.
abstract: FTY720 is a sphingosine-1-phosphate receptor agonist being developed as an immunomodulator for acute rejection prophylaxis after organ transplantation. This study was performed to characterize the pharmacokinetics of and lymphocyte response to multiple-dose FTY720. In this randomized, double-blind study, three groups of 20 healthy subjects each received either placebo, 1.25 mg/day FTY720, or 5 mg/day FTY720 for 7 consecutive days. FTY720 blood concentrations and lymphocyte counts were assessed over the weeklong treatment phase and over a month-long washout phase. The relationship between FTY720 blood concentrations and lymphocyte counts was explored by an inhibitory E(max) model. First-dose exposure was consistent with dose proportionality between the low- and high-dose groups. Blood levels accumulated fivefold over the treatment period. Exposure on day 7 was dose proportional for C(max) (5.0 +/- 1.0 vs. 18.2 +/- 4.1 ng/mL) and for AUC (109 +/- 24 vs. 399 +/- 85 ng.h/mL). Washout pharmacokinetics after the last dose indicated an elimination half-life averaging 8 days. Lymphocyte counts decreased by 80% in subjects receiving the lower dose to a nadir of 0.4 +/- 0.1 x 10(9)/L and by 88% in subjects receiving the upper dose to a nadir of 0.2 +/- 0.1 x 10(9)/L. Descriptive exposure-response modeling estimated that the lymphocyte response at 5 mg/day is near the maximal response achievable. By the end-of-study evaluation on day 35, lymphocyte counts had recovered to within 75% and 50% of baseline in the low- and high-dose groups, respectively. In summary, systemic exposure to FTY720 was consistent with dose-proportionality after both single- and multiple-dose administration. Total lymphocyte counts decreased from baseline by 80% and 88% at regimens of 1.25 and 5 mg/day, respectively. Exposure-response modeling provided evidence that 5 mg/day FTY720 resulted in a near-maximal dynamic effect of this drug on lymphocytes.
authors.affiliation: Novartis Pharma AG, Building WSJ 27.4093, 4002 Basel, Switzerland.
authors.forename: John M
authors.initials: JM
authors.lastname: Kovarik
authors.forename: Robert
authors.initials: R
authors.lastname: Schmouder
authors.forename: Denise
authors.initials: D
authors.lastname: Barilla
authors.forename: Gilles-Jacques
authors.initials: GJ
authors.lastname: Riviere
authors.forename: Yibin
authors.initials: Y
authors.lastname: Wang
authors.forename: Thomas
authors.initials: T
authors.lastname: Hunt
mesh_terms: D000284:Administration, Oral; D000293:Adolescent; D000328:Adult; D019540:Area Under Curve; D002214:Capsules; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D005260:Female; D000068876:Fingolimod Hydrochloride; D006207:Half-Life; D006801:Humans; D007166:Immunosuppressive Agents / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics; D018655:Lymphocyte Count / Q000379:methods; D008214:Lymphocytes / Q000097:blood / Q000187:drug effects* / Q000502:physiology; D008297:Male; D011409:Propylene Glycols / Q000008:administration & dosage* / Q000097:blood / Q000493:pharmacokinetics*; D013110:Sphingosine / Q000031:analogs & derivatives; D013997:Time Factors
chemical_list: D002214:Capsules; D007166:Immunosuppressive Agents; D011409:Propylene Glycols; D000068876:Fingolimod Hydrochloride; D013110:Sphingosine