Oral drug administration has been one of the most suitable and widely accepted by the patients for the delivery of most therapeutically active drugs. Various dosage forms like tablets, capsules and liquid preparations have been administered by oral route. But, due to some unsuitable physiological conditions of the gastro-intestinal tract such as :
  • relatively poor absorption
  • presence of various digestive enzymes of the gastro-intestinal lumen and epithelium
  • poor absorption efflux (i.e. by P-glycoprotein, etc.)
  • first pass metabolism by hepatic enzymes
the administration of some drugs is affected. Fast- or mouth dissolving tablets have been formulated for pediatric, geriatric, and bedridden patients and for active patients who are busy and traveling and may not have access to water. Such formulations provide an opportunity for product line extension in the Many elderly persons will have difficulties in taking conventional oral dosage forms (viz., solutions, suspensions, tablets, and capsules) because of hand tremors and dysphagia. Swallowing problems also are common in young individuals because of their underdeveloped muscular and nervous systems. Other groups that may experience problems using conventional oral dosage forms include the mentally ill, the developmentally disabled, and patients who are uncooperative, on reduced liquid-intake plans, or are nauseated. In some cases such as motion sickness, sudden episodes of allergic attack or coughing, and an unavailability of water, swallowing conventional tablets may be difficult.


Fast dissolving tablets are also called as mouth-dissolving tablets, melt-in mouth tablets, Orodispersible tablets, rapimelts, porous tablets, quick dissolving etc, are disintegrating and/or dissolve rapidly in the saliva without the need for water. Some tablets are designed to dissolve in saliva remarkably fast, within a few seconds, and are true fast-dissolving tablets. Others contain agents to enhance the rate of tablet disintegration in the oral cavity, and are more appropriately termed fast-disintegrating tablets, as they may take up to a minute to completely disintegrate.

This tablet format is designed to allow administration of an oral solid dose form in the absence of water or fluid intake. Such tablets readily dissolve or disintegrate in the saliva generally within less than 60 seconds.

The basic approach in development of FDT is the use of superdisintegrants like cross linked carboxymethyl cellulose (croscarmellose), sodium starch glycolate (primogel, explotab), polyvinylpyrollidone (polyplasdone) etc, which provide instantaneous disintegration of tablet after putting on tongue, their by release the drug in saliva. The bioavailability of some drugs may be increased due to absorption of drug in oral cavity and also due to pregastric absorption of saliva containing dispersed drugs that pass down into the stomach. More ever, the amount of drug that is subjected to first pass metabolism is reduced as compared to standard tablet.

The technologies used for manufacturing fast-dissolving tablets are freeze-drying, spray-drying, tablet molding, sublimation, sugar-based excipients, tablet compression, and disintegration addition.

Criteria for Fast dissolving Drug Delivery System: 
The tablets should :
  • Not require water to swallow, but it should dissolve or disintegrate in the mouth in matter of seconds. 
  • Be compatible with taste masking. 
  • Be portable without fragility concern. 
  • Have a pleasant mouth feel.
  • Leave minimum or no residue in the mouth after oral administration.
  • Exhibit low sensitive to environmental condition as temperature and humidity. 
  • Allow the manufacture of the tablet using conventional processing and packaging equipments at low cost. 
The ideal characteristics of a drug for FFDT include:
  • No bitter taste
  • Dose lower than 20mg 
  • Small to moderate molecular weight
  • Good stability in water and saliva 
  • Partially non ionized at the oral cavities pH
  •  Ability to diffuse and partition into the epithelium of the upper GIT (log P>;1, or preferably>2)
  • Ability to permeate oral mucosal tissue 
 Unsuitable drug characteristic for FDT :
  • Short half-life and frequent dosing
  • Very bitter or otherwise unacceptable taste because taste masking cannot be achieved
  • Required controlled or sustained release
Salient Feature of Fast Dissolving Drug Delivery System:
  • Ease of Administration to the patient who can not swallow, such as the elderly, stroke victims, bedridden patients, patient affected by renal failure and patient who refuse to swallow such as pediatric, geriatric & psychiatric patients.
  • No need of water to swallow the dosage form, which is highly convenient feature for patients who are traveling and do not have immediate access to water.
  • Rapid dissolution and absorption of the drug, which will produce quick onset of action.
  • Some drugs are absorbed from the mouth, pharynx and esophagus as the saliva passes down into the stomach. In such cases bioavailability of drug is increased.
  • Pregastric absorption can result in improved bioavailability and as a result of reduced dosage; improve clinical performance through a reduction of unwanted effects.
  • Good mouth feel property helps to change the perception of medication as bitter pill particularly in pediatric patient.
  • The risk of chocking or suffocation during oral administration of conventional formulation due to physical obstruction is avoided, thus providing improved safety.
  • New business opportunity like product differentiation, product promotion, patent extensions and life cycle management.
  • Beneficial in cases such as motion sickness, sudden episodes of allergic attack or coughing, where an ultra rapid on set of action required.
  • An increased bioavailability, particularly in cases of insoluble and hydrophobic drugs, due to rapid disintegration and dissolution of these tablets.
  • Stability for longer duration of time, since the drug remains in solid dosage form till it is consumed. So, it combines advantage of solid dosage form in terms of stability and liquid dosage form in terms of bioavailability.
  • Convenience in administration of drug and accurate dosing as compared to liquid formulations.
  • It provides advantages of liquid formulations in the form of solid dosage form.

Benefits of fast dissolving tablets
  • Patient compliance is more
  • Administered without water, anywhere, any time.
  • Suitability for geriatric and pediatric patients, who experience difficulties in swallowing and for the other groups that may experience problems using conventional oral dosage form, due to being mentally ill, the developmentally disable and the patients who are un-cooperative, or are on reduced liquid intake plans or are nauseated.
  • Beneficial in cases such as motion sickness, suede episodes of allergic attack or coughing, where an ultra rapid on set of action required.
  • Having rapid onset of action and increased bioavailability, particularly in cases of insoluble and hydrophobic drugs, due to rapid disintegration and dissolution of these tablets.
  • Stability for longer duration of time, since the drug remains in solid dosage form till it is consumed. So, it combines advantage of solid dosage form in terms of stability and liquid dosage form in terms of bioavailability.
  • Gives accurate dosing as compared to liquids
  • Free of need of measuring, an essential drawback in liquids
 Limitations of Fast Dissolving Tablets
  • The tablets usually have insufficient mechanical strength. Hence, careful handling is required.
  • The tablets may leave unpleasant taste and/or grittiness in mouth if not formulated properly.

Search