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Direct compression method..Mominul Islam
- 1. Assignment Course-Advanced Pharmaceutical Technology Course Code-PHR 5021.1 Topic –Direct Compression Method Prepared For: Dr. Md. Selim Reza Professor, Department of Pharmaceutical Sciences, North South University. Prepared By: Md. Mominul Islam ID# 162 1405 673 NSU_Mpharm-Summer, 2017.
- 2. Tablet ManufacturingMethods Direct compression Introduction In early days, most of the tablets require granulation of the powdered Active Pharmaceutical Ingredient (API) and Excipients. At the availability of new excipients or modified form of old excipients and the invention of new tablet machinery or modification of old tablet machinery provides an ease in manufacturing of tablets by simple procedure of direct compression. Direct compression is a popular choice because it provides the shortest, most effective and least complex way to produce tablets. The manufacturer can blend an API with the excipient and the lubricant, followed by compression, which makes the product easy to process. No additional processing steps are required. Moisture or heatsensitive ingredients, which would be contraindicated in wet granulation, can also be used in this type of process. However, it does require a very critical selection of excipients in comparison to granulation processes because the raw materials must demonstrate good flowability and compressibility for successful operation. Both high and low doses of API present a challenge in this respect. Most APIs tend to have poor compressibility, which affects the quality of tablets if the formulation calls for a large proportion of API. At the same time, there can also be problems when low amounts of actives need to be incorporated into tablets because it is difficult to accurately blend a small amount of active in a large amount of excipient to achieve the desired uniformity and homogeneity. For instance, segregation of the different components can occur. This means there is not a uniform distribution of tablet ingredients being fed to the press, and thus batchtobatch consistency of the manufactured tablet cannot be assured. One of the principal risk factors for segregation is the wide particle size distribution in direct compression formulations, in which active ingredients tend to be at the fine end of the range.
- 3. Where there is a wide range of particle sizes, there is an increased likelihood of sifting, where the smaller particles 'slip through' the bigger ones.Other bulk powder properties are also important for successful tabletting, such as good flowability, and all of these factors combine to place a high requirement on the excipients used for direct compression. Amongst the techniques used to prepare tablets, direct compression is the most advanced technology. It involves only blending and compression. Thus offering advantage particularly in terms of speedy production. Because it requires fewer unit operations, less machinery, reduced number of personnel and considerably less processing time along with increased product stability. By definition , direct compression are as follows… The term “direct compression” is defined as the process by which tablets are compressed directly from powder mixture of API and suitable excipients. No pretreatment of the powder blend by wet or dry granulation procedure is required. On the Otherhand, Direct compression is a dry process where in the powdered material (tablet formulation) is compressed directly into the tablets without the physical nature of the former being modified. Example- 1.Formulation of Ascorbic Acid Tablets. 2.Formulation of Chewable Antacid Tablets. The events that motivates the industry people to use direct compression technique:
- 4. I.Commercial availability of the directly compressible excipients possessing both good compressibility and good flowability.For example, Spray dried lactose, Anhydrous lactose, Starch-1500, microcrystalline cellulose, Di-Pac, Sorbitol II. Major advances in tablet compression machinery, i) Improved positive die feeding ii) Precompression of powder blend Manufacturing steps: Direct compression involves comparatively few steps: i)Milling of drug and excipients. ii)Mixing of drug and excipients. iii)Tablet compression.
- 5. Advantages of Direct Compression Direct compression is more efficient and economical process as compared to other processes, because it involves only dry blending and compaction of API and necessary excipients. The most important advantage of direct compression is economical process.Reduced processing time, reduced labor costs, fewer manufacturing steps, and less number of equipments are required, less process validation, reduced consumption of power. Elimination of heat and moisture, thus increasing not only the stability but also the suitability of the process for thermolabile and moisture sensitive API’s. Particle size uniformity. Prime particle dissolution. In case of directly compressed tablets after disintegration, each primary drug particle is liberated. While in the case of tablets prepared by compression of granules, small drug particles with a larger surface area adhere together into larger agglomerates; thus decreasing the surface area available for dissolution. The chances of batch-to-batch variation are negligible, because the unit operations required for manufacturing processes is fewer. Chemical stability problems for API and excipient would be avoided. Provides stability against the effect of aging which affects the dissolution rates. Merits over wet granulation process The variables faced in the processing of the granules can lead to significant tableting problems. Properties of granules formed can be affected by viscosity of granulating solution, the rate of addition of granulating solution, type of mixer used and duration of mixing, method and rate of dry and wet blending. The above variables can change the density and the particle size of the resulting granules and may have a major influence on fill weight and compaction qualities.
- 6. Drying can lead to unblending as soluble API migrates to the surface of the drying granules. Disadvantages of Direct Compression Excipient Related i)Problems in the uniform distribution of low dose drugs. ii)High dose drugs having high bulk volume, poor compressibility and poor flowability are not suitable for direct compression. For example, Aluminium Hydroxide, Magnesium Hydroxide iii)The choice of excipients for direct compression is extremely critical. Direct compression diluents and binders must possess both good compressibility and good flowability. iv)Many active ingredients are not compressible either in crystalline or amorphous forms. v)Direct compression blends may lead to unblending because of difference in particle size or density of drug and excipients. Similarly the lack of moisture may give rise to static charges, which may lead to unblending. vi)Non-uniform distribution of colour, especially in tablets of deep colours. Process Related i)Capping, lamination, splitting, or layering of tablets is sometimes related to air entrapment during direct compression. When air is trapped, the resulting tablets expand when the pressure of tablet is released, resulting in splits or layers in the tablet. ii)In some cases require greater sophistication in blending and compression equipments. iii)Direct compression equipments are expensive.
- 7. Direct compression Excipients Direct compression excipients mainly include diluents, binders and disintegrants. Generally these are common materials that have been modified during the chemical manufacturing process, in such a way to improve compressibility and flowability of the material. The physicochemical properties of the ingredients such as particle size, flowability and moisture are critical in direct compression tableting. The success of direct compression formulation is highly dependent on functional behavior of excipients. An ideal direct compression excipient should possess the following attributes i) It should have good compressibility. ii) It should possess good hardness after compression, that is material should not possess any deformational properties; otherwise this may lead to capping and lamination of tablets. iii) It should have good flowability. iv) It should be physiologically inert. v) It should be compatible with wide range of API. vi) It should be stable to various environmental conditions (air, moisture, heat, etc.). vii) It should not show any physical or chemical change in its properties on aging. viii) It should have high dilution potential. i.e. Able to incorporate high amount of API. ix) It should be colourless, odorless and tasteless. x) It should accept colourants uniformity. xi) It should possess suitable organoleptic properties according to formulation type, that is in case of chewable tablet diluent should have suitable taste and flavor. For example mannitol produces cooling sensation in mouth and also sweet test. xii) It should not interfere with bioavailability and biological activity of active ingredients.
- 8. xiii) It should be easily available and economical in cost. Major excipients required in direct compression I.Diluents II.Binders III.Disintegrants Diluents Selection of direct compression diluent is extremely critical, because the success or failure of direct compression formulation completely depends on characteristics of diluents. There are number of factors playing key role in selection of optimum diluent. Factors like- Primary properties of API (particle size and shape, bulk density, solubility), the characteristics needed for processing (flowability, compressibity), and factors affecting stability (moisture, light, and other environmental factors), economical approach and availability of material. After all, one can say that raw material specifications should be framed in such a way that they provide an ease in manufacturing procedures and reduce chances of batch to batch variation. Binders Binders are the agents used to impart cohesive qualities to the powdered material. The quality of binder used has considerable influence on the characteristic of the direct compression tablets. The direct compression method for preparing tablets requires materials which are not only free flowing but also sufficiently cohesive to act as binder.
- 9. Conclusion: Today, direct compression plays a key role in the pharmaceutical industry as the continuing trend towards generics requires manufacturers to design their production processes as efficient as possible. This is what direct compression delivers – formulation components are homogenized by mixing and then directly compressed into the final dosage form. However, in order to achieve a robust and lasting dosage form, the to be compressed functional components used in the mix must exhibit good flowability and compressibility. And this factor gets more important in case the amount of functional excipient in the formulation is reduced, i.e. due to a required high drug load or the drug itself is very poorly flowable or compressible. This is why we offer a range of high to highly effective direct compression binders, disintegrants and lubricants that will provide you all the design space you need for your formulation. And if you are working on a project where time-to-market is absolutely critical, we offer specialized ready-to-use premixes for tablets, orally disintegrating tablets and other dosage forms that will enable you to take the fast track towards your direct compression process.