Rahul Ratnakar*1, Lakshmi Goswami2, Dr. Preeti kothiyal
1Persuing M.Pharma
1,2Shri Guru Ram Rai Institute of Technology & Science,
P.O. Box - 80, Patel Nagar,
Dehradun 248001, Uttarakhand, India.

Oral delivery is currently the gold standard in the pharmaceutical industry where it is regarded as the safest, most convenient and most economical method of drug delivery having the highest patient compliance [1]. Mouth dissolving tablets are solid dosage forms containing drugs that disintegrate in the oral cavity within less than one minute the development of mouth dissolving tablets formulation is emerging and gaining popularity because it is easy to administer and leads to better patient compliance [2]. These are novel types; of tablets that disintegrate/dissolve/ disperse in saliva within few seconds’. According to European Pharmacopoeia, the ODT should disperse/disintegrate in less than three minutes. The basic approach used in development of MDT is the use of superdisintegrants like Cross linked carboxymelhylcellulose (Croscarmeliose), Sodium starch glycolate (Primogel, Explotab) (Polyplasdone) etc. which provide instantaneous disintegration of tablet after putting on tongue, thereby releasing the drug in saliva [3]. MDTs can be administered anywhere and anytime, without the need of water and are thus quite suitable for children, elderly and mentally disabled patients. This is seen to afflict nearly 35% of the general population and associated with a number of conditions, like parkinsonism, mental disability, motion sickness, unconsciousness, unavailability of water etc. To overcome such problems, certain innovative drug delivery systems, like ‘Mouth Dissolving Tablets’ (MDT) have been developed [4].



A fast-dissolving drug delivery system, in most cases, is a tablet that dissolves or disintrigrants in the oral cavity without the need of water or chewing. Most fast-dissolving delivery system films must include substances to mask the taste of the active ingredient. This masked active ingredient is then swallowed by the patient’s saliva along with the soluble and insoluble excipients.These are also called melt-in-mouth tablets, repimelts, porous tablets, oro-dispersible, quick dissolving or rapid disintegrating tablets.

An ideal Properties of FDT6
Require no water for oral administration, yet dissolve / disperse/ disintegrate in mouth in a matter of seconds.

Have a pleasing mouth feel. Have an acceptable taste masking property. Be harder and less friable Leave minimal or no residue in mouth after administration Exhibit low sensitivity to environmental conditions (temperature and humidity). Allow the manufacture of tablet using conventional processing and packaging equipments[5].

Advantages of MDT
a. No need of water to swallow the tablet [6].

b. Can be easily administered to pediatric, elderly and mentally

disabled patients.

c. Accurate dosing[7] as compared to liquids.

d. Dissolution and absorption of drug is fast, offering rapid onset of action.

e. Bioavailability of drugs is increased[8]as some drugs are absorbed from mouth, pharynx and esophagus through saliva passing down into the stomach[9].

f. Advantageous over liquid medication in terms of administration as well as

g. transportation

h. First pass metabolism is reduced, thus offering improved bioavailability and thus reduced dose and side effects.

i. Free of risk of suffocation due to physical obstruction when  swallowed, thus

j. offering improved safety.

1. Suitable for sustained/controlled release actives[10].

2. Allows high drug loading [3].

* Fast dissolving tablet is hygroscopic in nature so must be keep in dry place.

* Some time it possesses mouth feeling.

* MDT requires special packaging for properly stabilization & safety of stable product.

* 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 [2].

Challenges in formulating Fast dissolving tablets

As most drugs are unpalatable, FDTs usually contain the medicament in a taste-masked form. Upon administration, it disintegrate or dissolve in patient’s oral cavity, thus releasing the active ingredients which come in contact with the taste buds; hence, taste-masking of the drugs becomes critical to patient compliance[13].

Mechanical strength
In order to allow FDTs to disintegrate in the oral cavity, they are made of either very porous and soft  molded matrices or compressed into tablets with very low compression force, which makes the tablets friable and/or brittle, difficult to handle, and often requiring specialized peel-off blister packing that may add to the cost. Only Wow tab and durasolv technologies can produce tablets that are sufficiently hard and durable to allow them to be packaged in multi-dose bottles.

Several orally disintegrating dosage forms are hygroscopic and cannot maintain physical integrity. The application of technologies used for FDTs is limited by the amount of drug that can beincorporated into each unit dose. For lyophilized dosage forms, the drug dose must be less than 400 mg for insoluble drugs and 60 mg for soluble drugs. This parameter is particularly challenging when formulating a fast-dissolving oral films or wafers[14,20].

Amount of drug
The application of technologies used for FDTs is limited by the amount of drug that can beincorporated into each unit dose. For lyophilized dosage forms, the drug dose must be less than 400 mg for insoluble drugs and 60 mg for soluble drugs. This parameter is particularly challenging when formulating a fast-dissolving oral films or wafers [15].

Aqueous solubility
Water-soluble drugs pose various formulation challenges because they form eutectic mixtures, which result in freezing-point depression and the formation of a glassy solid that may collapse upon drying because of loss of supporting structure during the sublimation process. Such collapse sometimes can be prevented by using various matrix-forming excipients such as mannitol than can induce crystallinity and hence, impart rigidity to the amorphous composite[16] .

Size of tablet    The ease of administration of a tablet depends on its size. It has been reported that the easiest size of tablet to swallow is 7-8 mm while the easiest size to handle was one larger than 8 mm. Therefore, the tablet size that is both easy to take and easy to handle is difficult to achieve [3].

Conventional Techniques[11] :

Disintegrates addition: Disintegrate addition technique is one popular techniques for formulating Fast-dissolving tablets because of its easy implementation and cost-effectiveness. The basic principle involved in formulating Fast-dissolving tablets by disintegrates addition technique is addition of superdisintegrants in optimum concentration so as to achieve mouth dissolving along with the good mouth feel.

Molding: In this method, molded tablets are prepared by using water-soluble ingredients so that the tablets dissolve completely and rapidly. The powder blend is moistened with a hydro-alcoholic solvent and is molded into tablets under pressure lower than that used in conventional tablet compression. The solvent is then removed by air-drying. Molded tablets are very less compact than compressed tablets. These possess porous structure that enhances dissolution.

Freeze drying: A process in which water is sublimated from the product after freezing. Lyophilization is a pharmaceutical technology which allows drying of heat sensitive drugs and biological at low temperature under conditions that allow removal of water by sublimation. Lyophilization results in preparations, which are highly porous, with a very high specific surface area, which dissolve rapidly and show improved absorption and bioavailability.

Sublimation: The slow dissolution of the compressed tablet containing even highly water-soluble ingredients is due to the low porosity of the tablets. Inert solid ingredients that volatilize readily (e.g. urea, ammonium carbonate, ammonium bicarbonate, hexa methelene tetramine, camphor etc.) were added to the other tablet ingredients and the mixture is compressed into tablets. The volatile materials were then removed via sublimation, which generates porous structures. Additionally, several solvents (e.g. cyclohexane, benzene) can be also used as pore forming agents.

Spray-Drying: Spray drying can produce highly porous and fine powders that dissolve rapidly. The formulations are incorporated by hydrolyzed and non hydrolyzed gelatins as supporting agents, mannitol as bulking agent, sodium starch glycolate or cross carmellose sodium as disintegrating and an acidic material (e.g. citric acid) and or alkali material (e.g. I sodium bicarbonate) to enhance disintegration and dissolution. Tablet compressed from the spray dried powder disintegrated within 20 seconds when immersed in an aqueous medium.

Mass-Extrusion: This technology involves softening the active blend using the solvent mixture of water soluble polyethylene glycol, using methanol and expulsion of softened mass through the extruder or syringe to geta cylinder of the product into even segments using heated blade to form tablets. The dried cylinder can also be used to coat granules of bitter tasting drugs and thereby masking their bitter taste.

Direct compaction: Direct compration method is the easiest way to manufacture tablets. Conventional equipment, commonly available excipients and a limited number of processing steps are involved in direct compression. Also high doses can be  accommodated and final weight of tablet can easily exceed that of other production methods. Directly compressed tablet's disintegration and solubilization depends on single or combined action of disintegrants, water soluble excipients and effervescent agent.



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