A REVIEW ON: FORMULATION AND EVALUATION OF FAST DISSOLVING TABLET
Department of pharmacy,
b.u Bhopal (m.p.), India
The oral route of drug administration is the most important method for administering drugs for systemic effects. Except in certain cases the parenteral route is not routinely used for self administration, e.g. insulin. The topical route of administration has only recently been employed to deliver drugs to the body for systemic effects. The parenteral route of administration is important in treating medical emergencies in which the subject is comatose or cannot swallow. Nevertheless it is probable that at least 90% of all drugs used to provide systemic effects are administered by the oral route.
An Fast dissolving tablet, orally disintegrating tablet or orodispersible tablet (ODT) is a drug dosage form available for a limited amount of over-the-counter (OTC) and prescription medications. ODTs differ from traditional tablets in that they are designed to be dissolved on the tongue rather than swallowed whole. The ODT serves as an alternative dosage form for patients who experience dysphagia (difficulty in swallowing) or for where compliance is a known issue and therefore an easier dosage form to take ensures that medication is taken. Common among all age groups, dysphagia is observed in about 35% of the general population, as well as up to 60% of the elderly institutionalized population and 18-22% of all patients in long-term care facilities During the last decade, ODTs have become available in a variety of therapeutic markets, both OTC and by prescription. An additional reason to use an ODTs is the convenience of a tablet that can be taken without water.
REFERENCE ID: PHARMATUTOR-ART-1632
The oral route of drug administration is the most common route for systemic effect of drug. Solid dosage forms are most popular because ease of administration, accurate dosage, self medication, pain avoidance and most importantly patient compliance. The most commonly used solid dosage forms are tablets and capsules; one of the drawback for some patients, difficulty to swallow. Drinking water plays important role for swallowing of oral dosage forms.often times people experience inconvenience in swallowing conventional dosage forms such as water whereas water is not available in case of motion sickness( kenetosis) and sudden episodes of coughing during common cough and cold,allergic condition and bronchitis.
Recent developments in technology have presented viable dosage alternatives for patients who may have difficulty swallowing tablets or liquids. Traditional tablets and capsules administered with an 8-oz. glass of water may be inconvenient or impractical for some patients. However, some patients, particularly pediatric and geriatric patients, have difficulty swallowing or chewing solid dosage forms. Many pediatric and geriatric patients are unwilling to take these solid preparations due to fear of choking. For example, a very elderly patient may not be able to swallow a daily dose of antidepressant.
Orodispersible tablets are uncoated tablets intended to be placed in the mouth where they disperse rapidly before being swallowed.According to European Pharmacopoeia adopted the term "Orodispersible Tablet" as a tablet that to be placed in oral cavity where it disperses rapidly before swallowing. Orodispersible tablets dispers rapidly within 3 min.
HISTORICAL DEVELOPMENT OF ORODISPERSIBLE TABLETS
absorption and many have similar absorption and bioavailability to standard oral dosage forms with the primary route remaining GI absorption. However, a fast disintegration time and a small tablet weight can enhance absorption in the buccal area. The first ODTs disintegrated through effervescence rather than dissolution, and were designed to make taking vitamins more pleasant for children This method was adapted to pharmaceutical use with the invention of microparticles containing a drug, which would be released upon Tablets designed to dissolve on the buccal (cheek) mucous membrane were a precursor to the ODT. This dosage form was intended for drugs that yield low bioavailability through the digestive tract but are inconvenient to administer parenterally, such as steroids and some narcotic analgesics Absorption through the cheek allows the drug to bypass the digestive tract for rapid systemic distribution. Not all ODTs have buccal effervescence of the tablet and swallowed by the patient Dissolution became more effective than effervescence through improved manufacturing processes and ingredients (such as the addition of mannitol to increase binding and decrease dissolution time. Catalent Pharma Solutions (formerly Scherer DDS) in the U.K., Cima Labs in the U.S. and Takeda Pharmaceutical Company in Japan led the development of ODTs. The first ODT form of a drug to get approval from the U.S. Food and Drug Administration (FDA) was a Zydis ODT formation of Claritin (loratadine) in December 1996. It was followed by a Zydis ODT formulation of Klonopin (clonazepam) in December 1997, and a Zydis ODT formulation of Maxalt (rizatriptan) in June 1998. The regulatory condition for meeting the definition of an orally disintegrating tablet is USP method 701 for Disintegration. FDA guidance issued in Dec 2008 is that ODT drugs should disintegrate in less than 30 seconds. This practice is under review by the FDA as the fast disintegration time of ODTs makes the Disintegration test too rigorous for some of the ODT formulations that are commercially in the market.Difficulty in swallowing (Dysphagia) is a common problem in all age groups, especially the elderly and pediatrics, because of physiological changes associated with these age groups. It is common to see those afflicted carrying a small device with them, which is used for crushing tablets, enabling easy ingestion. Other categories that experience problems using conventional oral dosage forms include are the mentally ill, uncooperative and nauseated patients, those with conditions of motion sickness, sudden episodes of allergic attack and coughing. Sometimes, it may be difficult to swallow conventional products due to unavailability of water. These problems led to the development of a novel type of solid oral dosage form called mouth-dissolving tablets, which disintegrate and dissolve rapidly in saliva without the need of the water. They are also known as fast dissolving tablets, melt-in-mouth tablets, rapimelts, porous tablets, oro-dispersible, quick dissolving or rapidly disintegrating tablets.
Since 1986 when the Zydis® lyophilized, fast-dissolving dosage forms were first introduced, a number of other fast-dissolving formulations were developed, and the technology is still improving. Using the concept of, Scherer has patented the Zydis technology.
The network is highly porous solid form, which allows rapid penetration of liquid and facilitates quick disintegration of the dosage unit. The freeze-drying approach produces the fastest dissolving tablets, but the process is expensive, and the resulting tablets are mechanically weak. The other most widely used method to manufacture these tablets is via regular compression that can produce tablets with higher mechanical strengths. The disintegration or melting time of the compressed tablets is not as fast as the freeze-dried dosage forms, but the compressed tablets provide many advantages, such as high mechanical strength facilitating their handling and processing. The technology of the compressed tablets is also making major improvements, producing tablets that can melt within several seconds in the mouth.
DIFFICULTIES WITH EXISTING ORAL DOSAGE FORM
1. Patient may suffer from tremors therefore they have difficulty to take powder and liquids .In dysphagia physical obstacles and adherence to an esophagus may cause gastrointestinal ulceration. Liquid medicaments (suspension and emulsion) are packed in multidose container; therefore achievement of uniformity in the content of each dose may be difficult.
2. Buccal and sublingual formation may cause irritation to oral mucosa, so patients refused to use such medications.
3. Cost of products is main factor as parenteral formulations are most costly and discomfort. Swallowing of solid dosage form like tablet and capsules may zproduce difficulty for young adult of incomplete development of muscular and nervous system and elderly patients suffer from dysphagia. Cost of products is main factor as parenteral formulations are most costly and discomfort.
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