Drugs work: 101 Dalmatians content to be released (7)

I believe the answer is:

opioids

'drugs' is the definition.
(type of drug)

'work 101 dalmatians content to be released' is the wordplay.
'work' becomes 'op' (common abbreviation for 'opus').
'101' becomes 'ioi' (IOI resembles 101).
'content to be released' says to hollow out the word (remove centre letters) (the letters inside the word are released).
'dalmatians' with its middle removed is 'ds'.
'op'+'ioi'+'ds'='OPIOIDS'

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