INTRODUCTION:

Tablets are solid preparations each of which contains a single dose of one or more active ingredients, are obtained by compressing uniform volumes of particles, and are almost always intended for oral administration.

Tablets are the most commonly prescribed dosage form as offer a convenient form of drug administration provides dosage uniformity from tablet to tablet, stable over extended and diverse storage conditions, can be produced on high-speed compression, labelling, and packaging equipment. As a result, tablet production technology is constantly undergoing improvements that enhance their ability to deliver, with precisely, a desired drug in a dosage form intended for immediate or extended therapeutic effects¹.

Advancements in technology and modification in standard compressed tablet are to achieve better acceptability as well as bioavailability. Various types of newer and more efficient tablets are developed to create a delivery system that is relatively simple to administration. Recently some technical advancement viz. Capable of controlling the rate of drug delivery, Sustained duration of therapeutic activity and Targeted delivery of drug to tissues has resulted in the development of new techniques for drug delivery².

In recent decades, a variety of pharmaceutical research has been conducted to develop the Rapid Disintegrating tablet (RDT) is the most widely preferred commercial products. The oral cavity is an attractive site for the administration of drugs because of ease of administration³.

Various Types of Tablet:

Various types of tablets are being developed and used recently Table 1 describes the various types of tablets used now days.

Table 1: Different Type of Tablets

Oral Tablets for Ingestion

· Standard compressed tablet

· Multiple compressed tablet: Compression coated tablet/layered tablet/Inlay tablet

· Modified release tablet

· Delayed action tablet

· Targeted Tablet:

· Floating tablet/colon targeting tablet

· Chewable tablet

· Dispersible tablet

Tablets for Oral Cavity

· Lozenges and troches

· Sublingual tablet

· Buccal tablet

· Dental cones

· Mouth dissolved tablet

Tablets Administered by Other Routes

· Vaginal tablet

· Implants

Tablets for Solution Preparation

· Effervescent tablet

· Hypodermic tablet

· Soluble tablet

Various Novel/Advanced Types of Tablet Drug Delivery System:

Now a day’s various kinds of advanced tablets were developed and used according to Table 2.

Table 2: Different Types of Novel Tablet Drug Delivery Systems

Sr. No.	Types of Tablet
1.	Oral extended release tablets
2.	Osmotic pressure controlled tablets
3.	Multi-layered tablets formulations
4.	Gastroretentive buoyant drug delivery system
5.	Mucoadhesive drug delivery systems
6.	Targeted drug delivery system
7.	Colon specific drug delivery
8.	Miscellaneous
9.	Vaginal tablets
10.	Ion exchange resin system
11.	Rapid disintegrating tablet

Oral Extended Release Tablets:

Advanced technology has resulted in novel oral modified release dosage forms. Several terms are used to describe modified-release products including extended-release, prolonged-release, controlled-release, controlled-delivery, slow release and sustained-release. These preparations have a reduced rate of release of active substance. Generally, these terms are interchangeable. Delayed-release products are modified release, but by definition they are not extended-release⁴. They involve the release of discrete amount of drug after some time of drug administration, e.g. enteric-coated products, and exhibit a lag time during which little or no absorption occurs⁵. Several drugs are formulated as oral extended release tablets as shown in Table 3.

Various kinds of extend release tablets are used (e.g.,)

1. Diffusion-controlled system

2. Dissolution-controlled system

3. Erosion system

4. Reservoir devices

Osmotic Pressure Controlled Tablets:

In one sense osmotic pump systems are another type of membrane-controlled release drug delivery system and work in the following way. Drug is incorporated in a tablet core which is water soluble, and which will solubilize or suspend the drug in the presence of water. The tablet core is coated with a semi-permeable membrane which will allow water to pass through into the core, which then dissolves and as the core dissolves, a hydrostatic pressure builds up and forces (pumps) drug solution or suspension through a hole drilled in the coating⁶. The rate at which water is able to pass in through the membrane, and the rate at which the drug solution (or suspension) can pass out of the hole, govern the rate of release. Examples of drugs formulated as Osmotic pressure controlled tablets⁷.

Components of Osmotic Pump Systems:

Core consists of the active drug, a filler or substrate, a viscosity modifier), solubilizer and, lubricant/glidant. Coating contains a membrane polymer, plasticizer (membrane modifier), colourant and opacifier⁹.

Osmotic Pump System:

I. Rose-Nelson pump

II. Higuchi-Leeper pump

III. Higuchi-Theeuwes pump

IV. Elementary osmotic pump

Multi-Layered Tablet Formulation:

There are countless reasons to prefer a multi-layer tablet dosage form over a more conventional mono-layer tablet¹⁰. These can include the need to keep modified-release formulations separate from those that are immediately bioavailable, aesthetic appeal, combination products and product line extension etc. The most common multi-layer dosage form is the bi-layer (Figure 1), tri-layer and up to four or more layers^11,12.

Figure 1: Design of Bilayer Tablet

Advantages of Multi-Layer Tablet Technology:

The multi layer tablet offers Improved patient compliance, high drug loading capacity, Increased life cycle of a product, Ability to release multiple drugs, Broader range of release profiles, Low Cost by reducing manufacturing activities, Ability to separate incompatible drugs, Reduces unit to unit variations, Increased bioavailability of drugs and Unique, cost effective, dosage form¹³.

Challenges:

Conceptually, bi-layer tablets can be seen as two single-layer tablets compressed into one tablet but in practice, there are some manufacturing challenges¹⁴.

Gastroretentive Buoyant/Floating Drug Delivery System (FDDS):

Drugs having a short half-life are eliminated quickly from the blood circulation and therefore bioavailability of drug suffers. Gastro retentive dosage form improves bioavailability, therapeutic efficacy and allows a reduction in the dose because of steady therapeutic levels of drug. The reduction of fluctuations in the therapeutic levels minimizes the risk of resistance especially in case of ß-lactam antibiotics¹⁵. The ability of dosage form to prolong and control the gastric emptying time is a valuable asset for drugs acting on GIT. Prolonged gastric retention (Figure 2) improves bioavailability of drug, reduces drug waste and improves solubility of drugs that are less soluble in a high pH environment. Gastro retention provides better availability of new products with new therapeutic possibilities for patients^16,17.

Figure 2: Approaches to Floating Drug Delivery System (FDDS)

Advantages of FDDS:

These dosage forms are advantageous for drugs meant for local action in the stomach eg: Antacids. Floating dosage forms such as tablets or capsules will remains in the solution for longer time even at the alkaline pH of the intestine¹⁸. These dosage forms are advantageous in case of vigorous intestinal movement and in diarrhea to keep the drug in floating condition in stomach to get a relatively better response as well as drugs absorbed through the stomach eg: Ferrous salts, Antacids¹⁹.

Limitations of FDDS:

Floating systems are not feasible for those drugs that have solubility or stability problems in gastric reason. Drugs such as Nifedipine, well absorbed along the entire GI tract and undergo significant first-pass metabolism, may not be suitable candidates for FDDS since the slow gastric emptying may lead to reduced systemic bio-availability.

Such systems require a sufficiently high level of fluids in the stomach, so that the dosages form float therein and work efficiently²⁰.

Classification of FDDS Based on the Mechanism of Buoyancy:

A. Single Unit Floating Dosage Systems

· Effervescent Systems (Gas-generating Systems)

· Non-effervescent Systems

B. Multiple Unit Floating Dosage Systems

· Effervescent Systems (Gas-generating Systems)

· Non-effervescent Systems

· Hollow Microspheres

C. Raft Forming Systems

Mucoadhesive Drug Delivery Systems (MADDS):

Mucoadhesion is commonly used to describe an interaction between the mucin layer, which lines the entire GI tract, and a bio adhesive polymer, which could be natural or synthetic in origin. Drugs that undergo considerable first-pass metabolism through the liver are developed as Buccal and sublingual MADDS²². The MADDS favours Intimate and prolonged contact of the drug delivery device with the absorbing membrane, which has the potential to maximize both the rate and the extent of drug absorption, Prolonged and controlled GI transit time of the dosage forms²³. This system offers site-specific drug delivery, which has the potential for local therapy of several conditions, such as gastric ulcer, esophageal cancer, toothache, and dental sores, as well as the potential for the treatment of systemic diseases such as diabetes mellitus and angina pectoris etc²⁴.

Targeted drug delivery system:

Targeted drug delivery system implies selective and effective localization of drug into the targeted sites at therapeutic concentration with limited action to non-targeted sites.

A targeted drug delivery system is preferred in the following situations:

1. Pharmaceutical: Instability and low solubility of drug.

2. Pharmacokinetic: short half life, large volume of distribution, and/or poor absorption.

3. Pharmacodynamic: Low specificity, low therapeutic index etc²⁵.

Colon Specific Drug Delivery:

An ideal controlled drug delivery system is one which delivers the drugs at a predetermined rate, locally or systematically, for a specified period of time and an ideal targeted drug delivery system is the one which delivers the drugs only to its sites of action and not to the non-targeted organs or tissues²⁶. Colon targeted system is employed for the drugs that are destroyed by the acidic environment of the stomach or metabolized by pancreatic enzymes²⁷. This delivery system is used for the treatment of ulcerativecolitis, crohn's disease, colorectal cancer and inflammatory bowel diseases. Colonic drug delivery mainly accomplished by rectal or oral administration. Oral route is preferred over rectal administration for colonic delivery. Absorption or degradation of drug in the upper part of GIT is main obstacle and must be circumvented for successful colonic drug delivery.

Need of Colon Targeted Drug Delivery:

Targeted drug delivery to the colon would ensure direct treatment at the diseased site, lower dose required which reduces the side effect, delayed drug absorption can be achieved, allow oral administration of peptide and protein drugs, preferred in the treatment of colonic diseases, topical treatment of inflammatory bowel disease, for example Ulcerative Colitis or Cohn’s disease can be achieved. Formulations for colonic delivery are also suitable for delivery of drugs which are polar and/or susceptible to chemical and enzymatic degradation in the upper gastrointestinal tract, highly affected by hepatic metabolism²⁸.

Advantages:

Oral delivery of drugs to the colon is valuable in the treatment of diseases of colon such as ulcerative colitis, Cohn's disease, carcinomas and infections. Minimizing side effects that occur due to release of drugs in the upper GIT or unnecessary systemic absorption, poorly absorbed drug molecule may have an improved bioavailability. This region of the colon is recognized as a site having a somewhat less unreceptive environment with less diversity and intensity of activity than the stomach and small intestine²⁹.

Miscellaneous:

Ion Exchange Resins Tablet:

Some drugs can be bound to ion exchange resins and, when ingested, the release of drug depends on the ionic environment within the gastrointestinal tract. Duromine containing the basic drug phentermine complexed onto an anionic resin is also available in market³⁰.

Vaginal Tablets:

Vaginal tablets are used for many purposes such as infectious disease or their microbicide properties. One vaginal tablet has been investigated as a microbicide dosage form. Praneem poly herbal was originally formulated with purified ingredients from leaves of Neem (Azadirachta indica, fam. meliaceae), Sapindusmuker ossi (pericarp of fruit), and Mentha citrata oil into a pessary delivery device for spermicidal and contraceptive purposes. The poly herbal was further developed into a vaginal tablet, in clinical trials product was shown to be safe for vaginal use for up to 6 months with minor adverse effects³¹.

Rapid Disintegrating Tablets:

The concept of rapid disintegrating tablet emerged with an aim to improve patient’s compliance. These dosage forms rapidly disintegrate and dissolve to release the drug as soon as they come in contact with saliva, thus obviating the need for water during administration, an attribute that makes them highly attractive for pediatric and geriatric patients. Difficulty in swallowing conventional tablets or capsules is common among all age groups, especially in elderly and dysphagic patients. RDTs are known by various names such as fast-melting tablet, fast dissolving tablet (FDTs), oral disintegrating or orodispersible tablet. The European Pharmacopoeia describes the term “orodisperse” as a tablet that can be placed in the mouth where it disperses rapidly before swallowing³².

Ideal Properties:

An ideal RDT should:

· Require no water for oral administration.

· 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 equipments³³.

Advantages:

· Administration to the patients who cannot swallow, such as the elderly, bedridden patients, patients affected by renal failure and patients who refuse to swallow such as pediatric, geriatric and psychiatric patients.

· Rapid drug therapy intervention.

· Achieve increased bioavailability/rapid absorption through pre-gastric absorption of drugs from mouth, pharynx and oesophagus as saliva passes down.

· Convenient for administration and patient compliant for disabled, bedridden patients and for travellers and busy people, who do not always have access to water.

· Good mouth feel property helps to change the perception of medication as bitter pill particularly in pediatric patients.

· The risk of chocking or suffocation during oral administration of conventional formulations due to physical obstruction is avoided, thus providing improved safety.

· New business opportunity like product differentiation.

Salient Features:

· Ease of administration to patients who refuse to swallow a tablet, such as pediatric and geriatric patients and, psychiatric patients.

· Convenience of administration and accurate dosing as compared to liquids.

· Rapid dissolution of drug and absorption which may produce rapid, onset of action.

· Some drugs are absorbed from the pharynx and oesophagus as the saliva passes down into the stomach, in such cases bioavailability of drugs is increased³⁴.

· Ability to provide advantages of liquid medication in the form of solid preparation.

· Pre-gastric absorption can result in improved bioavailability and as a result of reduced dosage, improved clinical performance through a reduction of unwanted effects^34,35.

Disadvantages:

· Rapid Disintegrating tablet is hygroscopic in nature so must be keep in dry place.

· Some time it possesses mouth feeling

· RDT requires special packaging for properly stabilization and safety of stable product³⁶.

Technology for mouth dissolving tablets:

Conventional Techniques:

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 super disintegrants in optimum concentration so as to achieve mouth dissolving along with the good mouth feel³⁷.

Molding:

In this method, moulded 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. Moulded tablets are very less compact than compressed tablets. These possess porous structure that enhances dissolution³⁸.

Freeze drying:

A process in which water is sublimated from the product after freezing and lyophilisation 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. Lyophilisation results in preparations, which are highly porous, with a very high specific surface area, which dissolve rapidly and show improved absorption and bioavailability³⁹.

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 volatilematerials were then removed via sublimation, which generates porous structures. Additionally, several solvents (e.g. cyclohexane, benzene) can be also used as pore forming agents⁴⁰.

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 medium⁴¹.

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 get a 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 Compression:

Direct compression 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 disintegrates, water soluble excipients and effervescent agent.

Patented Technology:

Flashtab technolog:

Prographarm laboratories have patented the Flashtab technology. Tablets prepared by this system consist of an active ingredient in the form of micro crystals. Drug micro granules may be prepared by using the conventional techniques like coacervation, micro encapsulation, and extrusionspheronisation. All the processing utilized conventional tabletting technology.

Wowtab Technology:

Wowtab Technology is patented by "Yamanouchi Pharmaceutical Co." WOW means "Without Water ". In this process, combination of low mouldability saccharides and high mouldability saccharides is used to obtain a rapidly melting strong tablet. The active ingredient is mixed with a low mouldability saccharide and granulated with a high mouldability saccharide and compressed into tablet.

Flash Dose Technology:

Flash dose technology has been patented by "Fuisz". Nurofen meltlet, a new form of ibuprofen as melt-in-mouth tablets, prepared using flash dose technology is the first commercial product launched by" Biovail Corporation". Flash dose tablets consist of self-binding shearform matrix termed as "floss". Shearform matrices are prepared by flash heat processing.

Orasolv Technology:

Orasolv technology has been developed by "CIMA" labs. In this system active medicament is taste masked. It also contains effervescent disintegrating agent. Tablets are made by direct compression technique at low compression force in order to minimize oral dissolution time. Conventional blenders and tablet machine is used to produce the tablets. The tablets produced are soft and friable and packaged in specially designed pick and place system.

Durasolv Technology:

Durasolv is the patented technology of "CIMA" labs. The tablets made by this technology consist of a drug, fillers and a lubricant. Tablets are prepared by using conventional tableting equipment and have good rigidity. These can be packed into conventional packaging system like blisters. Durasolv is an appropriate technology for products requiring low amounts of active ingredients.

Table 7: Marketed Products of RDT^41,42

Sr. No.	Brand Name	Active Ingredient	Application	Company
1.	Clartin® Redi Tabs^®	Loratadine	Antihistamine	Schering corporation
2.	Feldene Melt^®	Piroxicam	NSAID’s	Pfizer
3.	Maxalt^®MLT^®	Rizatritpan Benzoate	Migrane	Merck
4.	Pepeid^®ODT	Femotidine	Antiulcer	Merck
5.	Zyperxa^®	Olazepine	Psychotropic	Eli Lilly
6.	Zofran^®M-Tab^TM	Olandansetron	Antiemetic	Galaxo Smith Kline
7.	Resperdal^®M-Tab^TM	Resperidone	Schizophrenia	Janssen
8.	Zubrin^TM(Pet drug)	Tepoxelin	Canine NSAID’s	Schering corporation
9.	Zelapar^TM	Selegiline	Parkinsons disease	Elanl Amarin corporation
10.	Klonopin^®wafer	Clonazepam	Sedation	Roche
11.	Childrens Dimetapp^®ND	Loratadine	Allergy	Wyeth consumer Healthcare
12.	Imodium Istant Melts	Loperamide HCL	Antidiarrheal	Jannsen
13.	Propulsid^®Quicksolv^®	Cisapride Monohydrate	GIT prokinetic agent	Jannsen
14.	Tempra Quicksolv^®	Acetaminophan	Analgesic	Bristol-Mters squibb

Zydis Technology:

Criteria for Drug Selection:

The ideal characteristics of a drug for in vivo dissolution from an RDT 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. Ability to permeate oral mucosal tissue.

Unsuitable drug characteristic for RDT:

· Short half-life and frequent dosing.

· Very bitter or otherwise unacceptable taste because tastemasking cannot be achieved. Required controlled or sustained release.

Super Disintegrants Used in RDTS:

As day’s passes, demand for faster disintegrating formulation is increased. So, pharmacist needs to formulate disintegrants i.e. Superdisintegrants which are effective at low concentration and have greater disintegrating efficiency and they are more effective intragranularly.

This superdisintegrants act by swelling and due to swelling pressure exerted in the outer direction or radial direction, it causes tablet to burst or the accelerated absorption of water leading to an enormous increase in the volume of granules to promote disintegration⁴³.

Figure 3: Schematic Diagram of Tablet Disintegration Mechanism

Delivery Mechanism of RDT:

· Various types of Super disintegrants used are as follows: Crosspovidone

· Microcrystalline cellulose

· Sodium starch glycollate

· Sodium carboxy methyl cellulose or cross carmelose sodium

· Pregelatinzed starch

· Calcium carboxy methyl cellulose

· Modified corn starch. Sodium starch glycollate has good flowability than crosscarmellose sodium.

Factors to Be Considered for Selection of Superdisintegrants:

· It should produce mouth dissolving when tablet meets saliva in the mouth

· It should be compactable enough to produce less-friable tablets.

· It can able to produce good mouth feel to the patient. Thus, small particle size are preferred to achieve patient compliance.

· It should have good flow since it improve the flowability of the total blend

EVALUATION:^44,45-55

Uniformity of Weight:

Procedure for uniformity of weight was followed, twenty tablets were taken and their weight was determined individually and collectively on a digital weighing balance. The average weight of one tablet was determined from the collective weight. The weight variation test would be a satisfactory method of determining the drug content uniformity.

Table 8: Weight Variation as Per IP

Sr. No.	Average Weight of Tablet	% Deviation
1.	80 mg or less	± 10
2.	More than 80 mg but less than 250 mg	± 7.5
3.	250 mg or more	± 5

Thickness:

Tablet thickness can be measured using a simple procedure. 5 tablets were taken and their thickness was measured using Varnier callipers.

Hardness:

It is the force required to break a tablet by compression in the radial direction, it is an important parameter in formulation of RDTs because excessive crushing strength significantly reduces the disintegration time. In the present study the crushing strength of the tablet was measured using Pfizer hardness testers. An average of three observations is reported⁴⁶.

Disintegration Time:

The test was carried out on 6 tablets using the apparatus specified in I.P.-1996 distilled water at 37ºC ± 2ºC was used as a disintegration media and the time in second taken for complete disintegration of the tablet with no palatable mass remaining in the apparatus was measured in seconds.

In-vitro Drug Release:

The development of dissolution methods for RDTs is comparable to the approach taken for conventional tablets, and is practically identical. Dissolution conditions for drugs listed in a pharmacopoeia monograph, is a good place to start with scouting runs for a bioequivalent RDT. Other media such as 0.1NHCl and buffers (pH - 4.5 and 6.8) should be evaluated for RDT much in the same way as their ordinary tablet counter parts⁴⁷.

The USP 2 Paddle apparatus is used for this purpose which is the most suitable and common choice for orally-disintegrating tablets, with a paddle speed of 50 rpm commonly used. Typically the dissolution of RDT is very fast when using USP monograph conditions; hence slower paddle speeds may be utilized to obtain a profile. The USP 1 Basket apparatus may have certain applications but sometimes tablet fragments or disintegrated tablet masses may become trapped on the inside top of the basket at the spindle where little or no effective stirring occurs, yielding irreproducible dissolution profiles.

Friability Test:

Friability of the tablets was determined using Roche friability (Electrolab, Mumbai). This device subjects the tablets to the combined effect of abrasions and shock in a plastic chamber revolving at 25rpm and dropping the tablets at a height of 6 inches in each revolution. Preweighed sample of tablets was placed in the friabilator and were subjected to 100 revolutions. Tablets were de dusted using a soft muslin cloth and reweighed. The friability (f) is given by the formula:

F= (1- W₀/W) × 100

Where, W₀ is weight of the tablets before the test and W is the weight of the tablet after the test.

In-Vitro Dispersion Time Test:

To determine dispersion time 10ml measuring cylinder was taken in which 6ml distilled water was added and tablet was dropped in it. Time required for complete dispersion was determined.

Wetting Time:

Five circular tissue papers of 10cm diameter are placed in a petridish with a 10cm diameter. Ten millimeters of water-containing Eosin, a water-soluble dye, is added to petridish. A tablet is carefully placed on the surface of the tissue paper. The time required for water to reach upper surface of the tablet is noted as a wetting time⁴⁸.

Water Absorption Ratio:

A piece of tissue paper folded twice was placed in a small Petri dish containing 6ml of water. A tablet was put on the paper and the time required for complete wetting was measured. The wetted tablet was then weighed. Water absorption ratio (R), was determined using following equation:

R = 10 (W_a/W_b)

Where, W_b is weight of tablet before water absorption and W_a is weight of tablet after water absorption⁴⁹.

CONCLUSION:

Rapid dissolving Tablets is the general form of nomenclature for tablets that disintegrate rapidly or instantly in the oral cavity. RDTs have better patient acceptance and compliance and may offer improved biopharmaceutical properties, improved efficacy, and better safety compared with conventional oral dosage forms. RDTs can be prepared in different ways and product performance depends upon the drug suitability and excipients selections in the delivery system. In combination with other technologies such as modified release and microencapsulation, RDTs will continue to provide enhanced commercial and therapeutic benefits. RDT is a growing technology, offering considerable benefits for lifecycle management16, development timelines, patient convenience and market share. By paying close attention to advances in technologies, pharmaceutical companies can take advantage of RDTs for product line extensions or for first-to-market products. With continued development of new pharmaceutical excipients, one can expect the emergence of more novel technologies for RDTs in the days to come. The successful marketed RDTs have good taste and rapid release properties. With rapid acceptance of RDTs by patients and pharmaceutical companies, the market for this dosage form is promising, and the product pipeline continues to grow rapidly.

CONFLICT OF INTEREST:

The authors have no conflicts of interest regarding this investigation.

ACKNOWLEDGMENTS:

The authors would like to thank Laureate Institute of Pharmacy for providing essential facilities during the study.

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Received on 20.05.2021 Modified on 07.06.2021

Asian J. Res. Pharm. Sci. 2021; 11(3):237-246.

DOI: 10.52711/2231-5659.2021.00038

Sr. No.	Brand Name	Company	Active Constituent	Therapeutic Use
1.	Tropol-XL	Astra Zeneca, Bangalore	Metoprolol succinate tablets	Hypertension
2.	Desoxyn	Abbot, Mumbai	Methampheta-mine-HCL tablet	Attention deficient/Disolver
3.	Ultramer® ER	Biovail, Canada	Tramadol HCL tablet	Analgesic
4.	Innopran XL	GlaxoSmithKline, Mumbai	Propranolol HCL	Hypertension
5.	Dolobid	Merck, NJ, USA	Difunisal tablet	Analgesic

Sr. No.	Brand Name	Company	Active Constituent	Therapeutic Use
1.	Minipress XL	Pfizer, NY (USA)	Prazosin HCL	Anti-hypertensive
2.	Cardura XL	Pfizer, NY (USA)	Doxzocin	Anti-hypertensive
3.	Covera HS	Pfizer, NY (USA)	Verapamil	Calcium channel blocker
4.	Efidac 24	Novartis, UK	Pseudoephiderine	Cholinergic agonist
5.	Procadila XL	Pfizer, NY (USA)	Nifedipine	Calcium channel blocker

Sr. No.	Brand Name	Company	Active Constituent	Therapeutic Use
1.	Madopar	Nicholas India	Levodopa and Benserzide	Anti-Parkinson
2.	Valrelease	Roche Pharmaceuticals, USA	Diazepam	Anti-Convulsants
3.	Topalcon	Pierre Fabre, Australia	Aluminium Hydroxide and Magnesium	Antacid

Sr.No.	Brand Name	Company	Active Constituent	Therapeutic Use
1.	Aftach	Angelini	Triamcinolone acetonide pharmaceuticals	Steroidal antiinflammatory
2.	Susadrin	Forest Laboratories	Nitroglycerin	Vasodilator
3.	Buccastem	Reckitt and Colman	Prochlorperazine	Antipsychotic