To determine the effects of steady-state concentrations of the selective S1P1 receptor modulator ponesimod on the pharmacokinetics ( PK ) of a single dose of a combined oral contraceptive , containing 1mg norethisterone ( NET ) and 35g ethinyl estradiol ( EE ) and to investigate the effects on heart rate at different ponesimod doses within an up-titration regimen prior to co-administration of the contraceptive .