**1. Introduction**

To maximize the safety and effectiveness of the medication molecule, pharmaceutical companies have developed oral disintegrating tablets that dissolve or disintegrate in the mouth after a few seconds of being placed there. It has gained popularity among a large population because it can be administered with ease to patients with weak physiological (patients with mental illnesses) and physical capacities, geriatrics, children, and patients with these conditions (patients suffering from dysphagia), as well as traveling patients who might not have easy access to water and where swallowing conventional solid oraldosage forms presents difficulties [1, 2].

The European Pharmacopoeia states that Orally Disintegrating Tablets (ODTs) are uncoated tablets that are intended to be placed in the mouth and then dispersed rapidly before being swallowed. The European Pharmacopeia specifies a limit of 3 minutes for the in vitro disintegration in water. A fast-dissolving drug delivery system is a novel drug delivery system that aims to improve the safety and efficacy of the drug molecule by formulating a dosage form that quickly dissolves in the mouth [3, 4]. Because it may be provided with ease to elderly patients, children, people with mental illness, people who have trouble swallowing, people who are traveling, and people who might not have access to water at all; it has gained popularity among the general population [5].

Liquid formulations for routinely used pediatric drugs, as well as for patients in an acute setting or with adherence issues, have been created by manufacturers. They are not without flaws, are frequently unstable, and have short shelf lives. Accurate dosage measurement and administration are also a challenge [6, 7]. As a result, both the pharmaceutical business and academics have recently become interested in the development of orally disintegrating tablets. Actually, ODTs are becoming more and more popular among patients, particularly those who are young and old and wish to have access to their prescriptions whenever they need it. Patients value these drugs' discretion and ease of use because they can be taken without water and start working right away [8]. As long as dispersion is rapid, bioavailability of the drug can be significantly greater than those observed from conventional tablet dosage forms [9].

#### **1.1 Pharmacokinetic and pharmacodynamics consideration**

As drug dissolves in saliva, it bypasses enterohepatic circulation and prevents firstpass metabolism by undergoing pre-gastric absorption. This improves bioavailability of the drug and reduces dosing frequency and dose-related untoward effects [10]. Orally disintegrating formulations are bioequivalent to the typical capsules now in use, with the added benefit of not requiring liquids. This allows for the management of emergent pain as soon as possible, regardless of the location or situation in which it occurs. The safety evaluation revealed that both orally disintegrating tablets and capsules were well tolerated, with no reported side effects. The similar maximum plasma concentrations (Cmax) achieved by both preparations are consistent with the lack of changes in safety parameters between the two formulations. Finally, from a practical standpoint, the availability of a bioequivalent tablet that can be eaten without liquids adds value because emergent pain can be addressed right away, regardless of where it occurs. This type of galenic formulation may also be beneficial for people who have difficulty swallowing or who have restricted mobility. It may also be of interest to institutionalized patients, as caregivers' jobs are made easier.

For example, salbutamol sulfate exhibits site-specific absorption in the stomach and upper parts of the small intestine [11]. Drug absorption requires molecules to be in solution at the absorption site. Conventional tablets may pass through the absorption site until they disintegrate and dissolve, resulting in reduced bioavailability. Because they appear as a solution at the absorption site, orally disintegrating tablets may increase the chances of being absorbed [12]. This may improve drug bioavailability, particularly for medicines with limited absorption sites in the small intestine [11, 13, 14].

Although albuterol and other ß2 agonists were formerly provided orally to provide a longer duration of action, this strategy is being phased out in favor of ß2 agonists that have a longer duration of action when administered via inhalation. Short-acting bronchodilators are the first line of treatment for COPD patients who have symptoms that come and go [15]. Drugs with very short half-lives need to be given at frequent dosing intervals to maintain therapeutic efficacy [16]. When the drug concentration is high and the enzyme is subjected to first-pass hepatic biotransformation [17], saturation occurs. As a result, the rate procedure is reduced to zero orders. As all of the enzyme molecules become complex with the drug, bioavailability may improve, and free drug may escape metabolism [11]. Drug bioavailability may be enhanced through oral cavity absorption as well as pregastric absorption of saliva-containing dispersed medicines

that move down into the stomach. Furthermore, when compared to traditional tablets, the amount of medication susceptible to first-pass metabolism is reduced [5].
