Possible Clues:

• Did the work I swallowed put me to sleep?
• Round at 'The Buccaneer' - right away it dulls the senses
• Drug I took at meal perhaps after operation
• Mind duller
• After work one ingested drug
• Endorphin, basically
• It will knock you out
• Old head has to take one sort of drug
• After work, I partook of heroin, perhaps
• Old detective consumed narcotic