WAFERS TECHNOLOGY – A NEWER APPROACH TO SMART DRUG DELIVERY SYSTEM
Papola Vibhooti *, Dr. Kothiyal Preeti
Shri Guru Ram Rai Institute of Technology & Sciences
Dehradun, Uttarakhand, India
The lyophilized wafer developed throughout this review is an effective and versatile drug delivery system for oramucosal application. This has been established from the extensive physicochemical and physic mechanical profiling conducted. Through a screening and selection of polymers, HPC had the lowest gelation characteristics and was therefore suitable for the development of the wafer system. Suitable excipient and polymer combinations were established which allowed for the development of rapidly disintegrating and prolonged release wafer systems. The wafer system containing HPC, lactose, mannitol and glycine had the ability to disintegrate within 30 seconds. The modified wafer system, consisting of pectin cross linked with zinc ions serving as the drug reservoir, and mucoadhesive polymer combination of pectin, carmellose and gelatin, provided effective release of model drug diphenhydramine hydrochloride over approximately six hours. The modification of this technology to provide a prolonged release mucoadhesive system seems promising. It is envisaged that this system will be applicable to many drugs requiring the extended release of bioactive material. Therefore, the lyophilized wafer matrices developed in this study are highly effective in the rapid delivery of drugs, using the oral route as a site of administration.
REFERENCE ID: PHARMATUTOR-ART-1908
Therapeutic value and pharmacoeconomic value have in recent years become major issues in defining health care priorities under the pressure of cost containment.  The improvement in drug therapy is a consequence of not only the development of new chemical entities but also the combination of active substances and a suitable Delivery system. The treatment of an acute disease or chronic illness is mostly accomplished by delivery of one or more drugs to the patient using various pharmaceutical dosage forms. Tablets, pills, capsules, suppositories, creams, ointments, liquids, aerosols, and injections are in use as drug carriers for many decades.
These Conventional types of drug delivery systems are known to provide a prompt release of the drug. Therefore, to achieve as well as to maintain the drug concentration within the therapeutically effective range needed for treatment, it is often necessary to take this type of drug several times a day, resulting in the significant fluctuation in drug levels. For all categories of treatment, a major challenge is to define the optimal dose, time, rate, and site of delivery. Recent developments in drug delivery techniques make it possible to control the rate of drug delivery to sustain the duration of therapeutic activity and/or target the delivery of drug to a special organ or tissue. Many investigations are still going on to apply the concepts of controlled delivery for a wide variety of drugs. 
The basic rationale for controlled drug delivery is to alter the pharmacokinetics and pharmacodynamics of pharmacologically active moieties by using novel drug delivery systems or by modifying the molecular structure and or physiological parameters inherent in a selected route of administration. It is desirable that the duration of drug action become more a design property of a rate - controlled dosage form and less, or not at all, a property of the drug molecules ’ inherent kinetic properties. 
The rationale for development and use of novel drug delivery systems may include one or more of the following arguments
- Decrease the toxicity and occurrence of adverse drug reactions by controlling the level of drug and/or metabolites in the blood at the target sites.
- Improve drug utilization by applying a smaller drug dose in a controlled – release form to produce the same clinical effect as a larger dose in a conventional dosage form.
- Control the rate and site of release of a drug that acts locally so that the drug is released where the activity is needed rather than at other sites where it may cause adverse reactions.
- Provide a uniform blood concentration and/or provide a more predictable drug delivery.
- Provide greater patient convenience and better patient compliance by significantly prolonging the interval between administrations.
“Accelerating Success Through Strategic Innovation” 
The oral mucosa provides the ideal application site for many active ingredients. Their diffusion into the dense network of capillaries ensures direct access to the blood stream –and excellent patient compliance.
Wafer – an innovative oral dosage form
New oral thin films, so-called wafers, thus creating new possibilities for action profiles and patient compliance.
Wafers are paper-thin polymer films used as carriers for pharmaceutical agents. The innovative dosage form is taken orally but does not require water or swallowing.
Effective absorption of active ingredient
The wafer quickly dissolves in the oral cavity, and the active ingredient can be absorbed into the blood - stream via the oral mucosa. The active ingredient, once absorbed by the oral mucosa, thus bypasses the liver’s first-pass effect, which improves bioavailability. Depending on the selected wafer type, the active ingredient’s release may also be delayed. In this case, it is absorbed after swallowing via the gastrointestinal tract.
Positive aspects with wafers (industrial point of view):
- Attractive dosage form with new active ingredients.
- Improvement of established products.
- Access to new indications by means of a new absorption profile even for existing active ingredients.
- Optimization of bioavailability.
- Increase patient compliance.
- Innovative technology for product.
- Increase of product appeal through innovative format.
- Exclusivity and cutting edge technology position in the market through an step forward.
Advantages of wafers
Marketing availability till date
Ranbaxy Laboratories received import permission for marketing the US FDA approved product Gliadel (polifeprosan 20 with carmustine implant) Wafer. The company has signed an exclusive licensing agreement with BioPro Pharmaceutical, USA, to promote and market Gliadel Wafer in India. Gliadel Wafer is for the treatment of newly diagnosed high-grade malignant gliomas and recurrent glioblastoma multiforme. There is very limited data available on the incidence of brain tumours in India, according to unofficial sources, the estimated prevalence of CNS tumours in India is two to five new cases per 1,00,000 per year. Another source estimates the total number of cases to be around 21,000 per year. Glioblastoma multiforme constitutes about 60-65 percent of these primary brain tumours.
Type of wafers
- Flash dissolved wafers
- Melt away wafers
- Sustained release wafers
- Flash dispersed wafers
Fig 1: Difference between sustained release and flash-dispersal wafers
Fig 2 : Difference between flash dissolve and melt – away wafers
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