[Codeine is a prodrug--the active agent is morphine].
Haavik
P E
PE
D000701:Analgesics, Opioid / Q000009:adverse effects*; D003061:Codeine / Q000009:adverse effects*; D006801:Humans; D009020:Morphine / Q000009:adverse effects / Q000494:pharmacology; D011355:Prodrugs; D013375:Substance Withdrawal Syndrome
D000701:Analgesics, Opioid; D011355:Prodrugs; D009020:Morphine; D003061:Codeine