Maldini, who plays for Cagliari, was among six people who suffered minor injuries when his Porsche Carrera collided with another vehicle in the northern part of the city at about 5:15 a.m. on September 13.
The 24-year-old forward had his driving licence confiscated by local police after he was found to be over the legal blood alcohol limit.
Maldini scored the winning goal in Cagliari's 1-0 victory over Udinese in Serie A on Saturday.
The son of former Italy and AC Milan defender Paolo Maldini, he received a call-up to the national team last week and has made six appearances for Italy.
After being taken to hospital for further checks, Maldini underwent testing for drug use. The results, released on Monday, ruled out the use of narcotic substances.
Maldini's lawyer, Danilo Buongiorno, said he was satisfied with the results.
"The findings confirm what Daniel has always maintained, namely that he has never used drugs," Buongiorno told Reuters. "The only remaining charge is drink-driving."
Daniel Maldini has played for several Serie A clubs, including Lazio, Atalanta and AC Milan.