The Long Island dermatologist and married mom whose body was found in the doorway of a Chelsea apartment building died of “acute cocaine and alcohol intoxication,” according to an autopsy report Monday.

“The manner of death is accident,” the city Medical Examiner’s Office added.

Dr. Kiersten Rickenbach Cerveny, a 38-year-old mother of three, was found unconscious early on Oct. 4 with her feet propping open the door of 223 W. 16th St. She was rushed to the hospital, where she was pronounced dead.

Police sources have said Cerveny went on a drug binge with married HBO producer Marc Henry Johnson, 51, before she collapsed.

She and Johnson, a longtime pal, allegedly met up during Cerveny’s wild girls’ night out on the Lower East Side. The group was partying hard until 2:30 in the morning. Then, at around 3 a.m., Cerveny and Johnson peeled off to go to his dealer’s apartment on West 16th Street, sources said.

After Cerveny collapsed, Johnson and the dealer, ex-con James Holder, carried her to the front of the building and left her there, sources said.

Holder fled, and Johnson called 911 before running off himself, they said.

Police said Monday that they don’t expect to make any arrests in the case.

After Cerveny’s death, Johnson took time off from his job as a producer of “The Deuce,” an HBO pilot about the porn industry starring James Franco and Maggie Gyllenhaal.

The producer was previously nominated for an Emmy for his work on Michael Moore’s “The Awful Truth.”

Holder, 60, disappeared after the incident. Authorities found numerous plastic zipper bags used to package narcotics in his apartment, sources said.

Neighbors of the Cervenys in Manhasset said she and her husband, fellow dermatologist Andrew Cerveny, had been living in a rented $1.2 million home there for about a year.

The house is adjacent to the Strathmore Vanderbilt Country Club, where one neighbor said Kiersten — a former pageant queen from New Jersey — taught water ballet.

Friends and neighbors described the couple and their three young children as the seemingly perfect family.

Neighbor Angelo Pappas, 46, said he often saw Cerveny and her husband jogging with their kids in a stroller at 6 a.m. And pal Penny Morash called Kiersten “a great mom.”

“Everybody thinks it’s horrible that this is what she’s going to be known for,” she said.