EXCLUSIVE

Chief Keef had a pharmacy of drugs in his system when he was busted for DUI ... TMZ has learned.

We broke the story ... Keef was arrested in April in Miami, after cops say they saw him doing a weed deal.

Play video content APRIL 2017 TMZ.com

Keef submitted to a urine test, and now we know the results, and they're pretty amazing ... Keef had the following drugs in his system:

-- Morphine

-- Codeine

-- Promethazine

-- THC

-- Hydrocodone

-- Norcodeine

-- Dihydrocodeine

-- Hydromorphone

8 drugs (EIGHT) in his system.

The State's attorney actually dropped the DUI Tuesday, but it was a scheduling issue. The DUI was refiled Wednesday.

BTW ... we learned firsthand how out of it Keef can be ... on "TMZ Live"