**4. Applications of alginates in orodispersible dosage forms**

Alginate is a natural polymer used widely in pharmaceutical, food, and biomedical applications because of its biodegradable and biocompatible properties. Alginate and its derivatives are considered low or nontoxic, and non-immunogenic hence suitable for human consumption [48, 49]. Moreover, various alginate salts (ammonium, calcium, sodium, potassium) and propylene glycol alginate derivatives are generally regarded as safe (GRAS) ingredients, for oral administration by the FDA. Like many other pharmaceutical products, the selection of excipients for orodispersible dosage forms requires thoughtful consideration based on the peculiar properties of the dosage form itself such as rapid disintegration, drugexcipient compatibility, biocompatibility with body fluids such as saliva and GIT fluids. Therefore, alginate and its derivatives have found different applications in the design and preparation of orodispersible dosage forms. As an example, sodium alginate has been used as an orodispersible film-forming polymer to provide mucoadhesive properties of the films or to increased drug loading or both. These applications are mostly accomplished with the sodium alginate alone to load poorly soluble drugs in ODF [22], or in combination with other polymers such as polyvinyl alcohol, chitosan, Carbopol 974P, and sodium carboxymethyl cellulose [22, 23, 50]. Various ODF formulations applying the uniqueness of alginates to provide different functions in the dosage form are exemplified in (**Table 1**). Indeed, it is worthy to note that, alginate-based orodispersible films have shown high tensile strength and high hydrophilicity with disintegration time within few seconds [20, 51]. Hence, the use of alginate in ODF represent good systems to formulate orodispersible dosage forms, promoting hydrophilic properties and ultimately suitable disintegration time which is fundamental quality for ODF. Nevertheless, few studies have explored alginate as a film-forming agent in ODF preparations either singly or in combination with other polymers. Thus, highlighting missing gaps to explore in discovering other potentials of alginates in ODF formulations [51].

Similarly, various alginate derivatives have also found application in the formulation of ODT where they serve different functionality. For instance, alginic acid and its salts have been used as disintegrants, super-disintegrants, and/or fillers in ODT formulations [24, 25]. Soulairol and co-workers developed xerogels containing alginic acid, calcium alginate or the combination thereof in the design and formulation of orodispersible mini tablets where they have been shown to provide enhanced super-disintegrant properties [25]. Further, Yehia et al., employed the use of sodium alginate as a taste-masking agent in ODT through solid dispersion technique. The authors succeeded in masking the taste of fexofenadine hydrochloride by controlling the rate of drug release in the saliva pH as confirmed by healthy human volunteers [26]. A summary of the various applications of alginates in ODT is also provided in (**Table 1**).
