Pharmacokinetics and safety of AMD-3100, a novel antagonist of the CXCR-4 chemokine receptor, in human volunteers

AMD-3100, a bicyclam, is a novel agent that uniquely inhibits the entry of human immunodeficiency virus type 1 (HIV-1) into CD4(+) T cells via selecti ve blockade of the chemokine CXCR-4 receptor, Twelve healthy volunteers wer e given AMD-3100 as a single 15-min intravenous infusion at 10, 20, 40, or 80 mu g/kg. Five subjects also received a single subcutaneous injection of AMD-3100 (40 or 80 mu g/kg). Three subjects received two escalating oral do ses each (80 and 160 mu g/kg). All subjects tolerated their dose(s) well wi thout any grade 2 toxicity or dose adjustment. Six subjects experienced mil d, transient symptoms, primarily gastrointestinal in nature and not dose re lated. All subjects experienced a dose-related elevation of the white blood cell count, from 1.5 to 3.1 times the baseline, which returned to the base line 24 h after dosing, AMD-3100 demonstrated dose proportionality for the maximum drug concentration in serum (C-max) and the area under the concentr ation-time curve from 0 h to infinity (AUC(0-infinity)) over the entire dos e range, At the highest intravenous dose (80 mu g/kg), the median C-max was 515 (range, 470 to 521) ng/ml and the AUC(0-infinity) was 1,044 (range, 98 0 to 1,403) ng-h/ml, The median systemic absorption after subcutaneous dosi ng was 87% (range, 67 to 106%). No drug was detectable in the blood followi ng oral dosing. Using a two-compartment model, the median pharmacokinetic p arameter estimates (ranges) were as follows: volume of distribution, 0.34 ( 0.27 to 0.36) liter/kg; clearance, 1.30 (0.97 to 1.34) liters/h; eliminatio n half-life, 3.6 (3.5 to 4.9) h. After a single, well-tolerated intravenous dose of AMD3100, concentrations were sustained for 12 h above the in vitro antiretroviral 90% inhibitory concentrations and for 8 h above antiviral c oncentrations identified in the SCID-hu Thy/Liv mouse model of HIV infectio n.