Caitlyn Jenner -- Victim's Stepkids Claim Drugs May Have Made Her a Bad Driver

Caitlyn Jenner's medications may have triggered her fatal car crash ... so claim the stepchildren of the woman killed in the accident.

The 2 stepkids filed legal docs in which they demand to know the meds Caitlyn was taking, saying they may have contributed to her ability to drive.

As for what type of meds ... all we know is that Jenner was tested after the accident and authorities determined she was not impaired at the time of the crash.

According to the legal docs, obtained by TMZ, Caitlyn has already taken the deposition of a paparazzo who was at the scene of the PCH crash, to determine if the photog caused or contributed to the crash.

Sources tell TMZ, Jenner has said she was being chased at the time of the crash.