This song has been covered by several bands and two versions can be found (the La's and one by Boo Radleys) on the soundtrack to the movie "So I married an Axe Murderer"
According to the There She Goes Songfacts, the common knowledge that this song is about heroin seems to be a sure bet. "Racing through my brain" and "Pulsing through my vein" exclude just about everything else, and newspapers in England ran…
There she goes
There she goes again
Racing thru' my brain
And I just can't contain