Sample collection and analysis
BLOOD
Blood and urine samples for PK analysis were collected from the individuals in all groups within 2 h before dosing and at 0.5, 1 1.25, 1.5, 2, 3, 5, 8, 12, 24, 36 and 48 h after dosing. Venous blood samples were collected in heparin treated tubes, and centrifuged within 30 min (400 × g, 4°C, 10 min). The upper plasma layer was collected, aliquoted and stored at −70 ± 10°C. Urine samples were aliquoted and stored at −70 ± 10°C. For RARβ2 expression in WBC from MAD cohorts, blood was collected before dosing and on Days 1, 2, 4, 7, 8, 9 and 14 and analysis carried out as described in 