The study had a double-blind , randomized , ascending single-dose design with an oral formulation F1 ( i.e. , ACT-281959 or placebo ) ( Part I ) and an open-label , randomized , 3-period , crossover design comparing exploratory formulations of ACT-281959 ( F2 ) 70mg and ACT-246475 ( dF ) 50mg to F1 70mg ( Part II ) .