The VEBER filter was developed by the analysis of 1,100 drug candidates. It seems that molecules fitting to these two properties have a high probability of good oral bioavailability in the rat.
Veber, Daniel F.; Johnson, Stephen R.; Cheng, Hung-Yuan; Smith,
Brian R.; Ward, Keith W.; Kopple, Kenneth D.
Molecular Properties That Influence the Oral Bioavailability of Drug
Candidates.
Journal of Medicinal Chemistry (2002), 45(12), 2615-2623.