Definition of ODT
Generally, an ODT is a solid-dosage form that disintegrates and dissolves in the mouth (either on or beneath the tongue or in the buccal cavity) without water within 60 seconds or less (1). The US Food and Drug Administration's Center for Drug Evaluation and Research developed the following definition for an ODT as a new dosage form in 1998: "A solid dosage form containing medicinal substances, which disintegrates rapidly, usually within a matter of seconds, when placed upon the tongue" (2).Earlier this year, FDA issued a draft guidance, Guidance for Industry: Orally Disintegrating Tablets (2), to recommend that, in addition to the original definition, ODTs be considered solid oral preparations that disintegrate rapidly in the oral cavity with an in vitro disintegration time of approximately 30 s or less, when based on the United States Pharmacopeia disintegration test method or alternative (see sidebar, "FDA issues ODT draft guidance").
Recent market studies indicate that more than half of the patient population prefers ODTs to other dosage forms, and most consumers would ask their doctors for ODTs (70%), purchase ODTs (70%), or prefer ODTs to regular tablets or liquids (greater than 80%) (1).
Mechanism of ODT drugs
Generally, ODTs are formulated to disperse rapidly in the mouth, enabling medication to be swallowed without water, thereby increasing convenience and compliance across a broad range of indications and patient types, including the young, elderly, and active patients, explains Susan Banbury, project manager with Catalent Pharma Solutions (Swindon, UK). Following dispersion, the formulations are typically swallowed, and the drug is absorbed in the same way as conventional solid-oral dosage forms.
"However, ODTs may also be used to deliver drugs to the oral cavity, for local action or, in some cases, absorption across the oral mucosa, thereby avoiding first-pass hepatic metabolism and potentially increasing the rate and extent of uptake, and reducing undesirable metabolites," says Banbury (4). The potential for such pregastric absorption rests largely in the physicochemical characteristics of the drug molecule. The intrinsic taste of the drug is also a significant consideration for all ODT formulations.
Types of ODTs