From a clinical trial synopsis (Boehringer Ingelheim 1239.1):
Dose: Starting dose of 150 mg b.i.d. (twice daily) BIBF 1120, followed by dose escalation of 50 mg for successive cohorts, up to a maximum of 250 mg b.i.d. (concomitant with BIBW 2992)
BIBF 1120 and BIBW 2992 are names of drugs. Is the word "concomitant" felicitous here, or is it better to use simultaneously with? What other naturally-sounding alternatives could there be?
I thought that we use "concomitant" when something happens by itself, but here the study authors chose to use this combination of drugs.