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REVIEW
ARTICLE
MANUFACTURING DEFECTS OF TABLETS
- A REVIEW
Abhinav Singh Rana*,
S.L. Hari Kumar
Rayat and Bahra
Institute of Pharmacy, Sahauran, Kharar, Distt:- Mohali, Punjab,India,-140104
*Corresponding Author’s
E-mail: abhinavsinghrana911@rediffmail.com,
Contact no: 07696436990
ABSTRACT
Tablet defects can come
from any of the unit operation upstream and from the tablet press. The raw
materials may be of poor quality or do not meet specification, causing
excessive fines that lead to a host of defects. The formulation may be the sour
ce of defects if the material do not compress well or the processing step
specified within the formulation fail to produce a powder a good flow,
compressibility, and ejection properties. The processing and granulation of
powder is often the source of 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.
Key words:
capping, mixing, granules, punches, compression, cracking
INTRODUCTION
An
ideal tablet should be free from any visual defect or functional defect. The
advancements and innovations in tablet manufacture have not decreased the
problems, often encountered in the production, instead have increased the
problems, mainly because of the complexities of tablet presses; and/or the
greater demands of quality. An industrial pharmacist usually encounters number
of problems during manufacturing. Majority of visual defects are due to
inadequate fines or inadequate moisture in the granules ready for compression
or due to faulty machine setting. Functional defects are due to faulty
formulation. Solving many of the manufacturing problems requires an in–depth
knowledge of granulation processing and tablet presses, and is acquired only
through an exhaustive study and a rich experience.
Here,
we will discuss the imperfections found in tablets along–with
their causes and related remedies. The mefcin
r nw s Vsa eet‘ and they are either related to
imperfections in any one or more of the factors.2
Tablet
processing problems can be due to the problem in the formulation or in the
compression equipment, or both of them. Thus we can classify the problems into
following types:
The defects related to Tabletting Process
i) Capping:
It is partial or complete separation of the top or bottom of tablet due
air-entrapment in the granular material.
ii)
Lamination: It is separation of tablet
into two or more
layers due to air-entrapment in the granular
material. iii) Cracking: It is due to rapid expansion of tablets when
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deep
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concave
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punches
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are
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used.2,
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3
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The
defects related to Excipient
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iv) Chipping: It
is due to
very dry granules.
v)
Sticking: It is the adhesion of
granulation material to the die wall
vi)
Picking: It is the removal of material
from the surface
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of
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tablet
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and its
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adherance to
the
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face
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of punch.
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vii)
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Binding: These problems (v, vi,
vii) are due to more
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amount of
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binder
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in the
granules
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or wet
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granules.
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The defect related to
more than one factor
viii) Mottling: It is either due to any
one or more of these factors: Due to a colored drug, which has different color
than the rest of the granular material (Excipient- related); improper mixing of
granular material (Process-related); dirt in the granular material or on punch
faces; oil spots by using oily lubricant.
The defect related to
Machine
ix) Double Impression: It is due to free
rotation of the punches, which have some engraving on the punch faces.
Further, in this section, each problem
is described along-with its causes and remedies which may be related to either
of formulation (granulation) or of machine (dies, punches and entire tablet
press).
CAPPING
‗apn‘ stetr sd hnteupro oe segment of the tablet separates horizontally, either
partially or completely from the main body of a tablet and comes off as a cap,
during ejection from the tablet press, or during subsequent handling.
Reason: Capping
is usually due to the air–entrapment in a compact during
compression, and subsequent expansion of tablet on ejection of a tablet from a
die.6,7
© 2011, JDDT. All Rights Reserved ISSN:
2250-1177 CODEN
(USA): JDDTAO
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Adjust
sweep-off blade correctly to facilitate proper ejection.
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Rana
et al Journal of Drug Delivery
& Therapeutics; 2013, 3(6), 200-206 201
The Causes
and Remedies of
Capping Related To
‗omlto‘ Gauain
Causes
I. Large amount of fines in
the granulation
II.
Too dry or very low moisture content
(leading to loss of proper binding action).
III. Not thoroughly dried
granules.
IV. Insufficient amount of
binder or improper binder.
V. Insufficient or improper
lubricant.
VI. Granular mass too cold.
Remedies
I.
Remove some or all fines through 100 to
200 mesh screen.
II.
Moisten the granules suitably. Add
hygroscopic substance e.g.: sorbitol, methyl- cellulose or PEG-4000.
III. Dry the granules
properly.
Reason:
Air–entrapment during compression and
subsequent release on ejection.
The condition is exaggerated by higher
speed of turret.8
The Causes
and Remedies of
Lamination Related To
Formulation
(Granulation)
Causes
I. Oily or waxy materials
in granules.
II. Too much of hydrophobic
lubricant.
III. Magnesium-stearate.
Remedies
I. Modify mixing process.
Add adsorbent or absorbent.
II.
Use a less amount of lubricant or change
the type of lubricant.
The Causes
And Remedies Of
Lamination Related To
‗ahn‘
De,PnhsAdTbe
Press)
Causes
IV. Increasing the amount of
binder.
V.
Adding dry binder such as
pre-gelatinized starch, gum acacia, powdered sorbitol, PVP, hydrophilic silica
or powdered sugar.
I.
Rapid relaxation of the peripheral
regions of a tablet, on ejection from a die.
II. Rapid decompression
VI. Increase the amount of lubricant or change the
type of lubricant.
VII. Compress at room
temperature.
The Causes
and Remedies Of
Capping Related To
‗ahn‘
De,PnhsAdTbe rs)
Remedies
I.
Use tapered dies, i.e. upper part of the
die bore has an outward taper of 3° to 5°.
II.
Use pre-compression step. Reduce turret
speed and reduce the final compression pressure.
Causes
I. Poorly finished dies
II.
Deep concave punches or beveled-edge
faces of punches.
III.
Lower punch remains below the face of
die during ejection.
IV. Incorrect adjustment of sweep-off blade. V. High
turret speed
Remedies
I.
Polish dies properly. Investigate other
steels or other materials.
II. Use flat punches.
III. Make proper setting of lower punch
during ejection.
IV.
CHIPPING
‗hpig‘i
eie stebekn ftbe de,while the tablet leaves the press
or during subsequent handling and coating operations. Reason: Incorrect machine
settings, specially mis-set ejection take-off.6
The Causes
And Remedies Of
Chipping Related To
Formulation
(Granulation)
Causes
I. Sticking on punch faces
II. Too dry granules.
III. Too much binding causes
chipping at bottom.
Remedies
I. Dry the granules
properly or increase lubrication.
II.
Moisten the granules to plasticize. Add
hygroscopic substances.
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V.
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Reduce speed
of turret (Increase dwell time).
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Optimize
binding, or use dry binders.
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LAMINATION
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‗aiain‘i h eaaino altit w rmr
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The Causes
And Remedies Of
Chipping Related To
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|||
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distinct
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horizontal
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layers.
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‗ahn‘ De,PnhsAdTbe rs)
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© 2011, JDDT. All Rights Reserved ISSN:
2250-1177 CODEN
(USA): JDDTAO
I. Groove of die worn at
compression point.
II. Barreled die (center of
the die wider than ends)
III. Edge of punch face
turned inside/inward.
IV. Concavity too deep to
compress properly.
Remedies
I. Polish to open end,
reverse or replace the die.
II. Polish the die to make
it cylindrical
III. Polish the punch edges
IV. Reduce concavity of
punch faces. Use flat punches.
The Causes
And Remedies Of
Sticking Related To
Formulation
(Granulation)
Causes
I. Granules not dried
properly.
II. Too little or improper
lubrication.
III. Too much binder
IV. Hygroscopic granular
material.
V. Oily or way materials
VI. Too soft or weak
granules.
Remedies
CRACKING
Small, fine cracks observed on the upper
and lower central surface of tablets, or very rarely on the sidewall are eerdt s‗rcs‘
Reason: It is observed as a result of
rapid expansion of tablets, especially when deep concave punches are used.9
The
Causes And Remedies
Of Cracking Related
To
Formulation
(Granulation)
Causes
I. Large size of granules.
II. Too dry granules.
III. Tablets expand.
IV. Granulation too cold.
Remedies
I. Reduce granule size. Add
fines.
II. Moisten the granules properly and add
proper amount of binder.
III. Improve granulation. Add
dry binders.
IV. Compress at room
temperature.
The
Causes And Remedies Of Cracking Related To Machine (Dies, Punches And Tablet
Press)
Causes
I. Tablet expands on
ejection due to air entrapment
II. Deep concavities cause cracking while removing
tablets
Remedies
I. Use tapered die.
II. Use special take-off.
STICKING
‗tcig‘rfr otetbe aeilahrn otedewall.
Filming
is a slow form of sticking and is largely due to excess moisture in the
granulation.
Reason:
Improperly dried or improperly lubricated granules.4
I.
Dry the granules properly. Make moisture
analysis to determine limits.
II. Increase or change
lubricant.
III.
Reduce the amount of binder or use a
different type of binder.
IV. Modify granulation and compress under
controlled humidity.
V. Modify mixing process.
Add an absorbent.
VI. Optimize the amount of binder and
granulation technique.
The Causes And Remedies Of Sticking
Related To Machine (Dies, Punches And Tablet Press)
Causes
I. Concavity too deep for
granulation.
II. Too little pressure.
III. Compressing too fast.
Remedies
I. Reduce concavity to
optimum.
II. Increase pressure.
III. Reduce speed.
PICKING
‗ikn‘ stetr sdwe ml muto aeilfrom
a tablet is sticking to and being removed off from the tablet-surface by a
punch face.
The problem is more prevalent on the
upper punch faces than on the lower ones. The problem worsens, if tablets are
repeatedly manufactured in this station of tooling because of the more and more
material getting added to the already stuck material on the punch face.
Reason: Picking is of particular concern
when punch tips have engraving or embossing letters, as well as the granular
material is improperly dried.4
The Causes
and Remedies Of
Picking Related To
Formulation
(Granulation)
© 2011, JDDT. All Rights Reserved ISSN:
2250-1177 CODEN
(USA): JDDTAO
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