Some of the research I have read suggests that the longer you can keep the B12 under the tongue the better the results. There is even some timed studies with different name brands, as each are different.

The Jarrow lasts much longer than the Enzymatic Therapy for me. The suggested length is 45 minutes, which is about the time I can keep Jarrow. Of course it is all dependant on things like how much you move it around in your mouth, how much saliva, if you drink during it, etc.

Enzymatic Therapy will only last 30 min if I am lucky, sometimes 20. Jarrow is a more chalky pill and ET is not so chalky, has a sweeter taste and is a smaller pill.