Emerging Perspectives in the Formulation of Lyophilized Orally Disintegrating Tablets: From Lyoc to Self-Nanoemulsifying Lyophilized Tablets (SNELTs) and Beyond into Hybrid Platforms.

Four decades have elapsed since orally disintegrating tablets (ODTs) were first formulated as the emulsion/type Lyoc tablet, a porous mass intended to rapidly disperse in saliva. Following the lyophilization process, new formulations of ODTs were designed, intending to make a simpler and more reproducible formulationZydis, LBL-Flash, Quicksolv, and, more recently, Zydis Ultra. Lyophilization is widely recognized as an effective technique for the development of ODTs, due to its ability to produce highly porous structures that enable rapid disintegration and improved patient compliance. However, its advantages should be considered in relation to other manufacturing methods, as each technology presents specific trade-offs in terms of cost, scalability, mechanical strength, drug loading capacity, and process robustness. In line with the modern sustainable and green pharmacy trend, new raw materials have gained attention as excipients for lyophilized ODTs; these materials include certain plant derivatives, but also performant excipients with newly discovered functionalities. At present, a new generation of ODTs is available in the form of Self-Nanoemulsifying Lyophilized Tablets (SNELTs), which bring the advantages of Self-Nanoemulsifying Drug Delivery Systems (SNEDDS) into ODTs via the lyophilization method. The technique is mostly applicable to low-solubility drugs formulated as nanoemulsions, which are absorbed onto solid carriers and further lyophilized, forming the final ODT. Despite its limitations (expensive, time-consuming, and high product friability), lyophilization is being continuously developed nowadays, in combination with other techniques (3D printing, mucoadhesion, or electrospinning), building hybrid platforms for the modern ODTs of the future.