The May 26 attack, captured on a Miami Herald security camera, had led to speculation the attacker, Rudy Eugene, was under the influence of harder drugs, the Herald reported.
The head of the Miami police union had speculated Eugene, who was fatally shot by a police officer, was under the influence of "bath salts," synthetic stimulants that have been blamed for what appeared to be psychotic episodes elsewhere in the country.
The medical examiner, who enlisted the help of an outside forensic toxicology lab, found no evidence of common ingredients of bath salts.
The Herald said the lab found no evidence of synthetic marijuana or LSD and the medical examiner found Eugene had not taken cocaine, heroin, PCP, oxycodone, amphetamines or any other known street drug other than marijuana, which isn't known to cause violence.
Eugene, 31, had stripped his clothes off along the MacArthur Causeway, then attacked 65-year-old Ronald Poppo.
Poppo is recovering at Jackson Memorial Hospital.