It's interesting that the debasement of the silver coins begins already with the Antonines--Antoninus Pius and Marcus Aurelius, considered "Good Emperors." Of course it gets much worse under the Severi and then during the period from 235 to 284 which was marked by frequent civil wars, barbarians invasions, and many short-reigned emperors.
Diocletian tried to stop inflation with his famous Edict of Prices, which had as much impact on prices as Canute's command to the tide not to come in had on the tide.