The sublingual tablet formulation is absorbed directly into the systemic circulation through the rich blood supply under the tongue. This bypasses the gastrointestinal tract and the first-pass hepatic metabolism in the liver, allowing the drug to reach effective plasma concentrations more rapidly. In contrast, oral tablets undergo extensive first-pass metabolism, reducing bioavailability. This property makes sublingual tablets ideal for drugs needing rapid onset or those extensively metabolized by the liver.

Reference: Goodman & Gilman's The Pharmacological Basis of Therapeutics, Brunton et al., 13th Edition.