Tablet defects and its rectification

Tablet defects can come from any of the unit operations upstream and from the tablet press. The raw materials may be of poor quality or do not meet specifications, causing excessive fines that lead to a host of defects. The formulation may be the source of defects if the material does not compress well or the processing step specified within the formulation fail to produce a powder with a good flow, compressibility, and ejection properties. The processing and granulation of powder are often the sources of the defect.
Every product behaves differently on a tablet press, even if it‘s the same product run on a different day. The variation often
stems from changes in the properties of the raw materials—active ingredients and excipients- from batch to batch. Naturally,
the goal is to minimize these changes. Tablet press operators, however, don‘t have any control over formulation and
granulation. Tablet specifications are tight, and the list of possible defects is long: Variable weight, sticking, picking, capping, lamination, variable hardness, among others. This article focuses on these variations. It pinpoints the possible causes of these defects and offers advice on preventing and fixing the source of the problems.

1. TABLET DEFECTS AND ITS RECTIFICATION Prepared & Presented by : Prof. Vedanshu R. Malviya ( M.pharm )

2. CONTENTS Introduction Defects in Tablets Its Rectification References

3. INTRODUCTION In the normal process of developing formulations, and in the routine manufacture of tablets, various defects are observed. Sometimes, the source of the problem or the defect is the formulation, the compression equipment, or a combination of the two. Some defects are noticed immediately during manufacturing but others may be noticed during storage as in the case of capping.

4. DEFECTS IN TABLETS AND ITS RECTIFICATION CAPPING AND LAMINATION PICKING AND STICKING MOTTLING DOUBLE IMPRESSIONS BINDING CHIPPING AND SPLITTING

5. CAPPING AND LAMINATION Capping is defined as the partial or complete separation of the top or bottom crowns of a tablet from the main body of the tablet. Lamination is the separation of a tablet into two or more distinct layers. These processing problems are readily apparent immediately after compression or may occur hours or even days later. Subjecting tablets to the friability test is the quickest way of revealing such problems.

6. CAPPING AND LAMINATION

7. Air entrapment Reduce press speed Precompress granulation Reduce quantity of fine particles in the granulation Excessive pressure Reduce tablet weight and/or increase its thickness within allowable tolerances Adjust pressure RECTIFICATION

8. Too rapid expansion of tablet upon ejection Taper dies Poor granulation Increase quantity of binder; use strong binder Excessively dry granulation Increase lubricant Excessive lubrication of granulation Decrease lubricant; blend all ingredients before adding lubricant

9. PICKING AND STICKING Picking refers to a tablet material being removed from the tablets surface by a punch. Sticking refers to a tablet material adhereing to die wall. Tablet materials adhering to punches can accumulate to the point of obliterating the tip design.

10. RECTIFICATION: Excessive moisture Check moisture content of granulation; drying Check room humidity Presence of low-melting-point substances Dilution with higher-melting-point materials Insufficient compaction force Reduce tablet weight and/or increase its thickness within allowable tolerances Inadequate lubrication of granulation Check and/or adjust level of lubricant used

11. MOTTLING Unequal distribution of color on a tablet, with light or dark areas standing out in an otherwise uniform surface.

12. RECTIFICATION: Drug whose color differs from the tablet excipients or a drug whose degradation products are colored. Use of colorants Migration of dyes to the surface of granulation during drying Change the solvent system Reduce the drying temperature Grind to a small particle size

13. DOUBLE IMPRESSION This problem is encountered with punches that have a monogram or other engraving on them. RECTIFICATION : Rotation of punches Adjust antiturning devices Use keyed punches

14. BINDING : Sticking of the tablet to the die and does not eject properly out of die. With excessive binding the tablet sides are cracked and it may crumble apart.

15. RECTIFICATION: To moist granules and extrudes around lower punch. Dry grannules properly Insufficient or improper lubricant Increase the amount of lubricant or use more effective lubricant Too coarse granules Reduce granular size,and more fines Granular material too warm , sticks to the die Reduce temperature Increase clearance if is extruding. .

16. CHIPPING OR SPLITTING Poor surface finish on punch tips; worn punches and dies Poor tooling design (e.g., sharp embossing or bisect lines) Polish punch tips; replace punches and dies

17. RECTIFICATION: Sticking on punch faces Dry the granules properly Or increase lubrication To dry granules . Moisten the grannules to plasticize add hygroscopic substances.

18. REFERENCES Herbert A. Lieberman, Leon Lachman , Joseph B. Schwartz, Pharmaceutical dosage forms : Tablets, Second Edition,vol 3. James Swarbrick , James C. Boylan , Encyclopedia of Pharmaceutical technology, Volume 15, 1996. James Swarbrick , Encyclopedia of Pharmaceutical technology, Third Edition , Volume 6, 2007. Website: www.pharmainfonet.com

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