The Versa™ platform is covered by an extensive intellectual property library and is responsible for the two FDA approved drug delivery products. It is based on a core of solid drug, coated with a semi-permeable polymer.  Water from tissue fluid diffuses into its core, leading to the dissolution of the drug, and resulting in a saturated solution within the polymer envelope. Drug in solution then diffuses out of the envelope based on the concentration difference between inside and outside. As the inside concentration remains saturated until virtually all of the drug is dissolved, and as the outside conditions are “sink,” the chemical potential which drives drug release is constant over the entire delivery period. This leads to pseudo-zero order release.