its in ur mind..if u cn eat n assimilate food u cn do the same thing with ur meds. its quite true once given iv route drug has immediate effect ..bt ultimately its the same drug..oral route do hv few problems here frst drug hs to absorbed n den it act.whreas iv route drug ur pouring directly in to blood so it hs less obstacles..so we need to tke care things wat vl effect absorption of drugs..like fr sm drugs we need to take it empty stomach sm full stomach if u do ulta it wont get absorbed properly n show less or no effect.