'Home Alone' Dad John Heard Had Various Narcotics in System at Time of Death

"Home Alone" dad John Heard had a pharmacy of drugs in his system when he died ... TMZ has learned.

The actor died in July at age 71, and now the toxicology results are in. Among the drugs in his system -- Tramadol, Oxycodone, Oxymorphone, Xanax, Buprenorphine, Fentanyl and Hydromorphone.

It's important to note Heard had back surgery 2 days before his death, and some of these drugs are commonly used to alleviate pain.

The report, obtained by TMZ, also seems to indicate there was an attempt to revive Heard with Narcan, a drug used to counteract the effects of a narcotics OD.

The Medical Examiner has already said Heard died from a heart attack triggered by heart disease. There is no information in the reports as to whether drugs contributed to the cause of death.