Why do we place it under our tongue?
This is because we want it to be absorbed in the blood by up to 90% more efficient to nerves quickly because there is a direct route mucous membrane capillaries ( blood vessels ) in addition to reducing the workload on of our body's systems.
If we follow the common way of consuming medicine, by swallowing; ABA24 Hablur/ Crystals will pass through the stomach acid and bile, then to the intestines, to the liver and eventually goes through various filtration. The absorption in the blood will also depends on the cleanliness of the intestine and absorption rate.
Therefore, by placing it under the tongue will intercept it all the way in order to carry out tasks quickly, and less systems/energy will be used for it to do its job.