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Orally disintegrating tablets, fast-dissolving, buccal and sublingual formulations

The oral mucosa offers a preferable route for both local and systemic delivery of drugs. This delivery route extends numerous advantages over the other delivery routes such as oral, parenteral and dermal, due to its rich blood supply, rapid onset of action, avoidance of the first pass metabolism as well as enzymatic degradation, which results in enhanced bioavailability, increased patient compliance, and ease of self-medication. Over the past three decades, orally disintegrating tablets (ODTs) as well as films, which require less than a minute to dissolve in the mouth, have gained more attention as an alternative to conventional sublingual, buccal formulations and lozenges. Orodispersible formulations have also been named as orally disintegrating, orodisperse, mouth-dissolving, quick-dissolve, fast-melt and rapid-disintegrating and freeze-dried formulations. The drug released from orodispersible formulations is absorbed through pregastric (oral cavity, pharynx, and esophagus), and gastric segments. Recent market studies indicate that more than half of the patient population prefers orally disintegrating dosage forms and most consumers would ask their doctors for ODTs (70%), purchase ODTs (70%). This can be attributed to the advantages of the ODTs offer, such as ease of administration, ease of swallowing, pleasant taste and flavor. In addition, ODTs provide clinical advantages such as improved safety and, in some cases, improved efficacy. From the industrial point of view, development of different orally disintegrating formulations (tablet, films etc.) technologies and commercialization of these products bring numerous marketing advantages such as expanded product lines, improved life-cycle management and extended patent life. Hence, development of new technologies and new disintegrants are still in progress. In this issue, readers will have the opportunity to explore examples of the recent studies in this area. Sublingual formulations exert similar characteristics to orally disintegrating formulations such as the short residence time in the mouth, rapid disintegration and dissolution, both being crucial for drug absorption following administration of sublingual tablets. For this reason, sublingual tablet formulations should be designed to disintegrate and dissolve rapidly in saliva, without the aid of water. Furthermore, for systemic effect, sublingual route provides faster absorption when compared to buccal route. In both cases; the hepatic first-pass effect as well as gastric degradation is avoided; therefore, the efficacy is enhanced. Up to date, numerous drugs have been investigated for sublingual and buccal delivery; however, there are few products available in the market, which are mostly fast dissolving formulations. Therefore, formulators continue to explore alternative approaches to enhance absorption of the drugs across oral mucosa. We hope that the scientists will benefit from reading the recent advances in the field of oral mucosal delivery contained in this issue.