Roman Holiday

Princess Anne becomes hysterical as her aid reads the schedule of another grueling day. Dr. Bonnachoven brandishes a syringe while telling her the "completely harmless" new drug will relax her and make her feel "a little happy." She manages to remain awake long enough to travel some distance from the embassy, but after reporter Joe Bradley finds her asleep by the sidewalk she remains either asleep, or in an intoxicated state Joe mistakes for drunkenness, until next morning. (0:11) She says the "dizziness is getting worse." (0:25)

What injectable sedative-hypnotic might a doctor have described as new circa 1953?

References in Finding Your Feet, L.A. Confidential