Mula education Society’s College of pharmacy Sonai Newasa-414105 Maharashtra, India.
Oral dosage form research has advanced significantly, with an emphasis on creating novel conventional dosage forms, particularly for patients who have swallowing issues. In order to increase patient compliance, Fast Dissolving Tablets have emerged as a potential type of tablets that dissolve or disintegrate quickly in the mouth when they come into contact with saliva. This makes the dosage form convenient.This article examines the best features, benefits, and potential drawbacks of FDTs compared to traditional dose forms. FDTs provide quick therapeutic action and rapid dissolution in the mouth, allowing for prompt absorption through the buccal mucosa in 15–120 seconds.These characteristics of the fast-dissolving tablet have been found to be very helpful for elderly and paediatric patients, as well as those who have swallowing difficulties. The benefits of FDTs include improving tongue feel and flavour masking, administering them to patients who are unable to swallow, providing mobile and bedridden patients with comfortable treatment, being easy to administer, and having accurate dosage. FDTs have drawbacks despite their benefits, such as problems with mechanical strength, brittleness, hygroscopicity, and challenges with bitter medications or offensive odours.
The majority of medications are taken orally in solid dose forms, such as tablets, powders, capsules, pills, and cachets. The oral method is the most popular since it is self-administered, inexpensive, non-invasive, and readily absorbed by the body like food. Changing the drug's dosage form makes it more appetizing, fashionable, and patient-acceptable. The dosage form's primary goal is to deliver the medication to the site of action for the greatest therapeutic impact and the fewest possible side effects. The reason "tablets" are the most popular of all the solid dosage forms is that they are easy to manufacture, more stable, precise in dosage, self-medicating, and least expensive. However, swallowing difficulties, especially in elderly, paediatric, bedridden, and mentally ill patients, result in poor patient compliance. In order to improve patient compliance and ease of administration, pharmaceutical scientists developed a number of novel drug delivery systems, including fast dissolving tablets, which are solid unit dosage forms containing medicinal agents that dissolve quickly when placed on the tongue in a matter of seconds. These tablets have the advantage of having a higher water absorption capacity, and swelling causes the tablet to burst and disintegrate quickly, giving them a significantly greater dissolution, absorption, and therapeutic effect than conventional tablets. FDT is frequently referred to as oral dispersible tablets, oral disintegrating tablets, rapid melts, mouth dissolving tablets, and melt-in-mouth tablets. [1,2,3]
Figure 1. Synonyms of FDT
The US FDA defines fast-dissolving tablets as "solid oral preparations that disintegrate rapidly in the oral cavity, with an in-vitro disintegration time of approximately 30 seconds or less. A tablet that dissolves in less than three minutes and dissolves quickly in the mouth before being swallowed is referred to as an Oro dispersible tablet, a term that was recently approved by the European Pharmacopoeia. For a variety of indications, including migraines, which require quick therapeutic action, and psychic illnesses, which require patient cooperation to treat chronic conditions like depression and schizophrenia, several FDT tablets have been developed. [4,5]
Advantages of Fast Dissolving Tablets:
Limitations of Fast Dissolving Tablets:
Ideal Properties of Fast Dissolving Tablets:
Benefits of FDTs Over Conventional Tablets:
Figure 2. Benefits of FDT
Challenges to Develop Fast Dissolving Tablets:
Palatability: Taste is a crucial factor in determining whether oral dose forms are acceptable. The majority of medications have a bitter taste, and many drugs are difficult to avoid. A flavour masking agent can be used to protect the tongue from being exposed to a bitter tasting medication. The most effective methods for masking flavour are coating, microencapsulation, granulation, and the addition of sweeteners.
Drug properties:The properties of the final tablet, including tablet strength and disintegration, can be greatly influenced by a drug's solubility, crystal shape, particle size, hygroscopicity, compressibility, and bulk density. The medications in Class II of the Biopharmaceutical Classification System that is, those with high permeability and poor water solubility are appropriate. Because it requires frequent administration, the drug's dosage should be minimal and its biological half-life should not be very short.
Mechanical strength: To break down in the oral cavity, the FDTs should be compacted into tablets with very little compression force or composed of soft-moulded, very porous matrices. However, this eventually makes the pills brittle and/or friable, making them challenging to handle and frequently necessitating specialist peel-off blister packing, which could raise the price. Only a select few technologies are able to create tablets that are robust and hard enough to be packaged in bottles with many doses.
Moisture sensitivity:The majority of the components in FDT formulations are hygroscopic. These components are sensitive to variations in the humidity and temperature of the air. As a result, they require extra protection in particular packaging. [11,12,13]
Criteria for Selection of Excipients in The Formulation of Fast Dissolving Tablet:
Excipients Used in Preparation of FDTs:
Superdisintegrants: The percentage of these used in FDT ranges from 1 to 15%. Because of their strong water absorption capacity and ability to cause rapid tablet bursting due to swelling, they are efficacious at low concentrations and have a disintegration time of less than one minute.Ex: Cross povidone, Sodium starch glycolate, Croscarmellose sodium. [16,17]
Factors To Be Considered For Selection of Superdisintegrants:
Mechanism of Action of Superdisintegrant:
The following mechanisms are involved in disintegration bysuperdisintegrants. [19,20,21]
Figure 3. Mechanism of Action of Superdisintegrants
Swelling: It is possible that swelling is the most commonly recognized overall mechanism of action for tablet disintegration. In tablets, swelling overcomes the adhesiveness of other components, causing the tablet to crumble. The poor disintegration of tablets with excessive porosity is caused by insufficient swelling force. The tablet with poor porosity, on the other hand, experiences adequate swelling force. It is important to remember that a very high packing percentage slows down disintegration since the fluid cannot enter the tablet.
Porosity and Capillary Action (Wicking): Porosity and capillary action are thought to be the mechanisms by which effective disintegrants that do not swell convey their disintegrating action. When the tablet is placed in an appropriate aqueous medium, the air that has been adsorbed on the particles is replaced by the medium, which weakens the intermolecular link and causes the tablet to break into tiny pieces. Fluid penetration into tablets is facilitated by tablet porosity. The disintegrant particles themselves, which have limited compressibility and cohesion, increased porosity and create these channels for fluid to enter the tablet. Tablet water uptake is dependent on tableting circumstances and the drug's or excipient's hydrophilicity. Maintaining a porous structure and low interfacial tension towards aqueous fluid are essential for these kinds of disintegrants because they aid in disintegration by forming a hydrophilic network surrounding the drug particles.
Particle Repulsion: An additional process of disintegration aims to explain why tablets containing "non-swellable" disintegrants swell. Since non-swelling particles also induce tablet disintegration, Guyot-Hermann has put forth a particle repulsion theory. Disintegration is caused by electric repulsive interactions between particles, and water is necessary for this process. It is discovered that wicking takes precedence over repulsion.
Deformation: When fragmented particles are compressed in tablets, they become distorted; when they come into touch with water or aqueous media, they return to their original shape. Granules were sometimes greatly distorted during compression, which increased the starch's ability to swell. As the size of the distorted particles increases, the tablet breaks apart. It is commonly believed that starch grains are "elastic," meaning that when pressure is applied, they would revert to their former shape. It is thought that these grains are more distorted due to the compression forces used in tableting and are "energy rich," which will be released when the grains come into contact with water.
Because of Heat of Wetting (air expansion): Capillary air expansion causes localized stress when exothermic disintegrants are wetted, aiding in tablet disintegration. However, the majority of contemporary disintegrating agents cannot be described by this theory, which is restricted to a small number of disintegrant kinds.
Due to Release of Gases: When bicarbonate and carbonate interact with citric or tartaric acid, carbon dioxide is liberated within the tablets upon wetness. The pressure created by the gas inside the tablet causes it to dissolve. Strict environmental control is necessary during tablet manufacturing since these disintegrants are extremely sensitive to even little variations in temperature and humidity. Either the effervescent blend is introduced right before compression, or it can be added to two different formulation fractions.
Enzymatic Reaction: In this case, the body's natural enzymes serve as disintegrants. These enzymes aid in disintegration by destroying the binder's binding activity. Due to swelling, pressure is applied externally, causing the tablet to rupture, or the rapid absorption of water results in a massive rise in granule volume, which facilitates disintegration.
Table 1. Examples of Disintegrating Enzymes
|
Sr. No. |
Enzyme |
Binder |
|
1 |
Amylase |
Starch |
|
2 |
Protease |
Gelatine |
|
3 |
Cellulase |
Cellulose and its derivatives |
|
4 |
Invertase |
Sucrose |
Diluents: These are included in FDT formulations to improve tableting qualities and enhance tablet weight when active ingredient concentration is low. These kinds of dosage forms, like spray-dried lactose, mannitol, and poly dextrose, use sugar-based diluents due to their good water solubility and pleasant mouthfeel. When using the direct compression method, microcrystalline cellulose is the ideal diluent due to its exceptional compressibility. Diluent concentrations in the final formulation range from 10% to 90%. [22]
Lubricants: In addition to making the tablet more pleasant after dissolving in the mouth cavity, they are also added in tablet formulation to lessen friction between the tablet's walls and die cavity. To move the formulation from the mouth cavity to the stomach, lubricants are also helpful. For example, Aerosil, Talc, and Magnesium Stearate
Sweeteners and Flavours: In order to improve patient acceptability and make fast-dissolving pills more pleasant, sweeteners are added to lessen their bitter flavour. The most popular natural sweeteners are sugar, fructose, and dextrose. Synthetic sweeteners like aspartame and sodium saccharine are also often used. FDTs contain flavours to lessen the unpleasant smell of the active components and make the formulation more appealing and patient-acceptable. It is possible to add both natural and artificial flavour.[23]
Preparation Methods of Fast Dissolving Tablets:
Direct Compression Method: This approach saves money and requires few processing steps. Typical manufacturing tools and widely used excipients, such as microcrystalline cellulose, a direct compressible diluent, are used. Sodium starch glycolate, croscarmellose sodium, crospovidone, and indion414 are among the superdisintegrants added for quick disintegration. This procedure involves passing all weighed ingredients through a sieve to ensure that they are all the same size before mixing them all together. Finally, the tablet is squeezed once the lubricant has been added. In the case of FDTs, however, the use of extra superdisingrants can occasionally result in tablets that are less firm and more brittle.[24]
Freeze Drying or Lyophilization: Freeze drying is a pharmaceutical technique that improves FDTs' oral bioavailability, solubility, and disintegration. This approach is especially helpful for biological products and medications that are sensitive to heat since it sublimates water out of the formulation. This medication is released into blister packs after being dissolved or distributed in a water-soluble polymer matrix. In order to finish the operation, the nitrogen flush was used to freeze out and then stored in the refrigerator. The main drawbacks of this approach are its high cost, time commitment, and fragility, necessitating specialist packaging.[25]
Moulding: Sugars and other water-soluble substances were utilized in this procedure to improve the drug's solubility. To create moulded tablets, a powder mixture is moistened with a hydroalcoholic solvent and then the wet mass is compressed. Due to the drying process, these tablets developed pores, which accelerated the rate of tablet disintegration. As a result, rapid drug dissolution eventually results in rapid drug absorption. Sugars are employed in these tablets to provide a pleasant mouthfeel. However, moulded tablets are more friable and have less physical integrity.[26]
Spray Drying: In this technique, the matrix is supported by hydrolysed or unhydrolyzed gelatine. Bulking agents like mannitol are utilized. Among the superdisintegrants included in the formulation are sodium starch glycolate, croscarmellose sodium, and crospovidone. Additionally, effervescent substances like sodium bicarbonate and citric acid are added to promote dissolving and disintegration. After creating a porous product through spray drying, the composition is crushed into tablets. The disintegration time of FDTs made using this technology was shorter than 20 seconds.
Sublimation: This process involves combining volatile chemicals including urea, benzoic acid, camphor, ammonium bicarbonate, ammonium carbonate, naphthalene, and urethane with additional excipients to compress them into tablets. These tablets are then vacuum-exposed at 80°C for 30 minutes in order to eliminate volatile components and produce porous structures that aid in the tablets' quick disintegration.[27]
Phase Transition: This process involves combining sugar alcohols with high and low melting points, such as erythritol (which has a high melting point of 122°C) and xylitol (which has a low melting point of 93–95°C), with additional excipients, then compressing the mixture into tablets. The tablets are then heated in an oven to a temperature that maintains the xylitol's melting point. When heated, xylitol diffuses and forms against the tablets, creating pores that can cause the tablets to disintegrate quickly.[28]
Nanonization: This new technique was created recently and uses the wet grinding method to reduce particles to nano size. Physical adsorption on the surface of inert material stabilizes the produced nanocrystals to avoid agglomeration. This technique works especially well for medications that are poorly bioavailable and soluble in water. It is an easy technique that is economical, flexible, and incorporates high dosages.
Cotton Candy Process: This technique creates a matrix of polysaccharides by melting and spinning at the same time. After being recrystallized, the candy matrix is ground, combined with the active ingredient and additional excipients, and crushed into tablets. This approach has strong mechanical strength and can integrate big doses.[29]
CONCLUSION
A major development in pharmaceutical science, oral fast-dissolving tablets (FDTs) provide a workable option for patients who have trouble swallowing conventional dosage forms. The demand for improved patient-friendly medication administration methods, particularly for paediatric, elderly, and dysphagic populations, has fuelled the development of FDTs. Carefully choosing ingredients like flavouring agents, binders, and superdisintegrants that guarantee quick disintegration, stability, and palatability is essential to the success of FDTs. Continuous improvements in manufacturing processes, like direct compression and lyophilization, have made it possible to produce FDTs with improved drug release patterns and scalability. There are still issues with stability, flavour masking, and manufacturing complexity, but new developments like mucoadhesive systems and nanotechnology show promise for resolving these obstacles.In conclusion, FDTs have a very bright future. The potential to enhance medication delivery, increase patient compliance, and meet unmet medical requirements keeps growing as new materials and technologies are developed. The next generation of oral fast-dissolving drug delivery systems will be greatly influenced by additional research and development in the fields of formulation, manufacturing, and clinical application.
REFERENCES
Abhishek Khole*, Vilas Ghawate, Vishal Balme, A Comprehensive Review on Advancement in Oral Fast Dissolving Tablet Technologies and Material, Int. J. of Pharm. Sci., 2025, Vol 3, Issue 01, 1132-1140. https://doi.org/ 10.5281/zenodo.14649649
10.5281/zenodo.14649649
