The BBC Past Doctor Adventures was a series of paperback novel releases by BBC Books, launched in 1997 in conjunction with its Eighth Doctor Adventures line. The line featured new adventures of the first seven Doctors, with the exception of four releases: Scream of the Shalka, which was a novelisation of a webcast story featuring the alternative Ninth Doctor; The Infinity Doctors, featuring an unspecified Doctor; The Face of the Enemy, featuring the Master; and one of the last novels, Fear Itself, which was the only PDA with the Eighth Doctor in a lead role, acknowledging the coming of the Ninth Doctor on television.
The series ended in late 2005 (along with the EDA line) when BBC Books decided to focus its publishing ventures on books related to the revived TV series. Although there was speculation regarding the PDA line resuming with novels featuring the Eighth Doctor and even the Ninth Doctor, as of 2013 the line has yet to resume in its original paperback format.
That's not, of course, to say that there haven't been a few other "adventures involving past Doctors" that have been published since the advent of the BBC Wales era. But things like the Short Trips series of short story anthologies and mass market hardcovers like Harvest of Time have a different format to the Past Doctors Adventures range.