HomePharmacy Which route of administration would provide the most rapid onset of action response to morphine.. I.V Which route of administration would provide the most rapid onset of action response to morphine? a- oral b- S.C. c- I.V. d- I.M. e- rectal Facebook Twitter Share:Which route of administration would provide the most rapid onset of action response to morphine.. I.V Facebook Twitter WhatsApp Pinterest LinkedIn Reddit Tumblr Telegram Email