After racemic lansoprazole is applied orally, 80% of the circulating drug is dexlansoprazole. Moreover, both enantiomers have a similar effect on the proton pump.^[3] Consequently, the main advantage of Kapidex is not the enantiopure substance, but the pharmaceutical formulation.

Kapidex is based on a dual release technology, with the first quick release producing a plasma peak concentration about one hour after application, and the second retarded release producing another peak about four hours later.^[2][4] As of November 2009, clinical relevance of this form of release has yet to be shown.

Dexlansoprazole selectively inhibits the parietal cell membrane enzyme (H⁺,K⁺)-ATPase, typically referred to as the proton pump, thus blocking the final step of acid production.^[5]

Antacid preparations such as dexlansoprazole, by suppressing acid mediated break down of proteins, lead to an elevated risk of developing food and drug allergies. This happens due to undigested proteins then passing into the gastrointestinal tract where sensitisation occurs. It is unclear whether this risk occurs with only long-term use or with short-term use as well.^[6]