Is there a consistent way of doing the potion drop glitch in the purple block room in the lost catacombs, while falling on the right hand side of the spikes?

Yes. How I do this skip is I jump and hold left when the screen stops scrolling, and if that fails you can always get to the load zone from wherever you are by alternating whip and jump. Just be sure not to cannon or you'll lose the ability to refresh your jump.