studies on tableting properties of mixture containing...
TRANSCRIPT
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Pharma Science Monitor 8(2), Apr-Jun 2017
STUDIES ON TABLETING PROPERTIES OF MIXTURE CONTAINING
SARPAGANDHA ROOT POWDER UNDER THE IMAPCT OF VARIOUS
EXCIPIENTS
A. K. Patel*, T. M. Patel
Department of Pharmaceutics and Pharmaceutical technology, L.M.College of Pharmacy, Navrangpura,
Ahmedabad-380009, Gujarat, India
ABSTRACT
The objectives of this study were to check the compression and compaction behaviour of
Sarpagandha root powder with different excipients i.e. Avicel PH 102, Avicel PH 200, Directly
compressible lactose 21, Starch 1500, Dicalcium phosphate dihydrate, Dicalcium phosphate,
tricalcium phosphate and lactose monohydrate.In this work, direct compression and dry
granulation methods were used for tablet preparation. Comparison of direct compression and dry
granulation were also carried out. Tableting properties such as flow property, compressibility and
compactibility were evaluated. Compressibility and compactibility attributes of Sarpagandha root
powder with different excipient were determined with Heckel Plot, Walker analysis, Kawakita’s
equation, and Kuno’s equation. In direct compression process, Avicel PH 200 mixture was found
to be superior as compared to other directly compressible excipient. In case of dry granulation
process, Tricalcium phosphate (TCP) has was found to be higher in comparison with other
excipients studied. However, direct compression with Avicel PH 200 mixture exhibited
improved flow properties and compressibility at low yield pressure as linked to granules
prepared by dry granulation with TCP. Walker co-efficient promote the results obtained from
Heckel analysis.
KEYWORDS: Compressibility, Compactibility, Sarpagandha root powder, Heckel plot, Walker
analysis.
INTRODUCTION
The objective of the present work was to study the tableting properties of Sarpagandha root
powder in presence of various tableting excipients. The root powder is obtained from Rauwolfia
serpentine Bentham ex Kurz roots (Family: Apocynaceae) which is widely used as
antihypertensive. [1-2]
Due to poor flowability and compaction behaviour, sarpagandha powder frequently request a
granulation prior to tableting. To increase the therapeutic performance and stability of
sarpagandha root powder, methods like direct compression (DC) and dry granulation (DG) can
be used. Moreover, direct compression and dry granulation is correlated with lower cost and less
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time consuming manufacturing process. Conventional wet granulation incorporatesmixing of the
powders, adding of agglomerating solution, kneeding or massing of moist powders.[3]By the use
of directly compressible excipient one can compress tablet of sufficient mechanical strength by
using different excipients.
The description and proper explanation of the properties of pharmaceutical materials is critical to
effectively and rationally develop pharmaceutical dosage forms. The practical performance of
tablet excipients can be assessed with the excipients as powders, as a dosage form of pure
excipients and as a formulation of a given drug holding the excipients. The excipients are
involved in a formulation as they own properties that in conjunction with a process let the
production of a dosage form with the mandatory specifications.
The part of excipients in drug product development includes targeting the drug profile andcontrol
the final characteristics of the ending product. The efficientpresentation of tablet excipients can
be measured with the excipients as powders, dosage form of pure excipients and as a formulation
of a given drug containing the excipients.[4]
The aim of this work is to check compressibility and compactibility of mixtures of Sarpagandha,
directly compressible diluents, glidants and lubricants will be prepared in order to finalize the
optimal ratio of active material and excipients which furnish a sufficient mechanical strength of
tablets. Directly compressible diluents considered in this study include Microcrystalline cellulose
(Avicel PH 102 and Avicel PH 200), directly compressible lactose (DCL 21), Dicalcium
phosphate dehydrate, Tricalcium phosphate, Dicalcium phosphate and Pregelatinized starch
(Starch 1500). Excipients used in this study for dry granulation include Microcrystalline
cellulose (Indian pharmacopoeia grade), Dicalcium phosphate dihydrate (powder form), Lactose
monohydrate, Tricalcium phosphate and Dicalcium phosphate. DC excipients shows some
benefit such as good flow properties and high mechanical strength of tablets.
MATERIALS AND METHODS
Materials
Sarpagandha root powder was purchased online from R.R. Herbals, Tamilnadu with batch No:
Q21. Microcrystalline cellulose (Avicel PH 102; Avicel PH 200 and Indian Pharmacopoeia
grade); directly compressible lactose (DCL 21); dicalcium phosphate dehydrate were obtained as
gift sample from Intas Pharmaceuticals Limited, Ahmedabad. Dicalcium phosphate; tricalcium
phosphate; lactose monohydrate; crosscarmellose sodium, talc, magnesium stearate were
purchased fromFinar Chemicals India Pvt. Ltd.; Ahmedabad. All the excipients were stored in
air tight containers at 25 ± 2 °C and 40 ± 5 % RH conditions.
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Preparation of tableting mixtures by direct compression
Accurately weighed quantity of Sarpagandha root powder, directly compressible diluent,
crosscarmellose sodium, talc, magnesium stearate are passed separately through sieve of mesh
size 40. All ingredients except magnesium stearate are mixed for 5 min in a cone shaped blender.
The composition was again mixed with magnesium stearate for 2 minutes. The powder mixture
was directly compressed in a rotary tablet compression machine. Capsule shaped punch sets were
used with the dimensions of 21.10 mm X 10.10 mm. Average weight of tablets prepared by
direct compression was 914 mg.
Preparation of tableting mixtures by Dry Granulation
Accurately weighed quantity of sarpagandha root powder, Non DC diluent, crosscarmellose
sodium, talc, magnesium stearate are passed separately through sieve of mesh size 40. All
ingredients are mixed in for 5 minutes in cone shaped blender. Slugs are produced by
compressing the material in rotary tablet compression machine by using 20/32” flat round shaped
punches. Slugs are milled through # 20 sieve to prepare granules. The granules are compressed
in rotary tablet punching machine to prepare tablets. Capsule shaped punch sets were used with
the dimensions of 21.10 mm X 10.10 mm. Average weight of tablets prepared by direct
compression was 702 mg.
Characterization of tableting mixtures and tablets
Flow properties of tableting mixture
Flow properties of the tableting mixture were determined by measuring the angle of repose and
Carr’s index as per USP29-NF24 (<1174> Powder flow).[5]
Tablet crushing strength
Tablet breaking force was determined by diametric compression on a Dr. Schleuniger
Pharmatron Tablet Tester 8M according to USP29-NF24 (<1217> Tablet breaking force).[6]
Tablet friability
Tablet friability (%) was determined according to USP29-NF24 (<1216> Tablet friability) by
using a friability tester Electrolab Friabilator USP (XXIII).[7]
Tablet disintegration
Disintegration time was measured by using disintegration machine THERMONIK, Campbell
Electronics TD-2 as per USP29-NF24 (<701> Disintegration). [8]
Compressibility
Heckal plot
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The most commonly practical method in pharmaceutical technology for evaluating
compressibility is the Heckel model. The Heckel equation delivers a method of compression
pressure and displacement signals to linear relationship for materials undertaking compaction.
The equation undertakes that at applied pressure the densification of powder bed follows first
order, with inter particulate pores as the reactant and the densification of the powder bed as the
product.[9] Tableting mixtures containing sarpagandha and diluents were compressed using 12
mm diameter of flat faced punch at various applied pressures (0.5, 1, 1.5, 2, 2.5 and 3 tons) using
KBr press (Wika quality systems, Germany). The die and punch were lubricated using 1% w/v
dispersion of Magnesium stearate in acetone. Heckel equation is described by the formula:
−ln = (1
1−D) = KP + A (1)
Where, 'D' is the solid fraction (the ratio of tablet density to true density of powder) at applied
pressure 'P' in tons. (1-D) denotes the % porosity (Є) of the powder material. 'K' is the material-
dependent constant (the slope of the straight line portion of the Heckel plot). The reciprocal of
'K' is the mean yield pressure (Py) Intercept 'A' gives the densification of the powder bed as a
result of initial particle rearrangement.
'D' value was calculated by determining the diameter and thickness of the compacts after each
applied pressure in tons. Compression behavior of the respective powders was expressed as
parameters of Heckel equation. Heckel analysis was carried out by intrigue the graph of ln (1
1−𝐷)
Vs P. A high Heckel coefficient displays a materials propensity towards fragmentation, while a
low value means that the material is plastically deformable [16-17]. Heckal reported that the
linear portion of the plot represents the densification process by particle deformation after
intraparticular bonding and that soft, ductile powders have lower yield pressure. Agglomerates
that have the lowest value undergo plastic deformation. The yield pressure value reflects the
compression characteristics of the material: the lesser the value of (Py), the greater the tendency
towards plastic deformation.
Walker analysis
Walker equation is used for compressibility study. It involves plotting the specific volume of the
powder compact against logarithm of the axial pressure applied.[10]The equation is described by:
V’ = w’ logP + V’sp (2)
Where, V’ is specific volume of a tablet and w’ is the walker coefficient stating the volume
reduction corresponding to change in pressure P obtained by linear regression analysis and V’sp
is the specific volume at pressure 1 (ton) of KBr press.[11]
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Compactibility
Kawakita’s equation
The packability of agglomerates of the tableting mixture containing sarpagandha and diluents
was established by comparing the constants a, b and k in Kawakita’s and Kuno’s equations,
respectively. For the analysis purpose, 20 gm of tableting mixture was tapped in the 100ml
measuring cylinder on a tap density tester (Electrolab ETD-1020, India). Initial bulk volume (v0)
was noted. Thereafter tapped volume was noted after predetermined taps
(5,10,15,20,25,50,75,100,200,300,400 and 500). The tapped volume at 500th tap is referred to as
equilibrium volume. The data were analyzed using following equation,
n
c=
1
ab+
n
a (3)
Where,
a =(v0−vinf)
v0 ; c =
(v0−vn)
v0; n = tap number; V0, Vn and Vinf are the powder bed volumes at initial,
after nth tapping (5, 10, 15, 20, 25, 50, 75, 100, 200, 300 and 400 ) and at equilibrium state (500th
tap) respectively. The constant ‘a’ represents the proportion of consolidation as closest packing is
attained. The reciprocal of b and k represents the packing velocity.
Kuno’s equation
For the analysis purpose, 20 gm of tableting mixture containing sarpagandha and diluents was
tapped in the 100ml measuring cylinder on a tap density tester (Electrolab ETD-1020, India).
Initial bulk volume (v0) was noted. Thereafter tapped volume was noted after predetermined taps
(5, 10, 15, 20, 25, 50, 75, 100, 200, 300, 400 and 500). The tapped volume at 500th tap is referred
to as equilibrium volume. The data were analyzed using following equation:
ρf
− ρn
= (ρf
− ρ0
)e−kn (4)
Where, ρ0, ρn and ρf are the apparent densities at initial state, after nth tapping, and at equilibrium
state respectively; and n is number of taps.
Tensile strength
The tensile strength (σ) calculated using following equation,
σ =2𝐻
П𝑑ℎ; (5)
Where, H is the tablet crushing force, d is the tablet diameter and h is the tablet thickness.[13]
Elastic recovery
The compacts used in the Heckel plot analysis were subjected to relaxation period of 24 hours to
critic the elastic behavior of the powder bed under examination. The thickness of compacts was
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recorded instantly after ejection (Hc) from the KBr press and after 24 hours relaxation period
(He).[13]
%ER= [ (He−Hc)
Hc] × 100 (6)
Results and discussion
Characterization of mixtures
Flow properties of tableting mixture
The flow properties results are shown in table 1. The flow properties are evaluated in terms of
Carr’s index and angle of repose. Good flow properties was observed with the tableting mixture
Avicel PH 102, Avicel PH 200, DCL 21, Starch-1500, DCP and TCP in case of direct
compression. In case of dry granulation, tableting mixture showed good flow property after
slugging and milling process.
Table1: Flow properties of Different Directly compressible excipients with Sarpagandha
root powder for direct compression method
Batch
No
Excipient in
tableting
Mixture*
AOR
(º)
Bulk
Density
(gm/cm3)
Tapped
density
(gm/cm3)
Carr’s
Index
(%)
Flow
properties
SAT3 Avicel PH 102 33.60 0.8 0.71 0.3 0.83 0.3 14.46 Good
SAT6 Avicel PH 200 33.40 1.2 0.65 0.5 0.76 0.4 14.48 Good
SAT9 DCL 21 32.16 0.9 0.84 0.3 0.95 0.2 11.57 Good
SAT12 DCPD 38.320.8 0.89 0.3 1.11 0.3 19.81 Poor
SAT15 Starch-1500 31.76 0.9 0.89 0.2 1.00 0.2 11.00 Good
SAT18 DCP 34.50 0.4 0.98 0.4 1.17 0.2 16.24 Good
SAT21 TCP 34.10 0.7 0.90 0.4 1.05 0.2 14.29 Good
*Each batch contains excipients (525mg); Sarpagandha root powder (325mg); Crosscarmellose
sodium (5%), Talc (2%), and magnesium stearate (1%). DCL 21= directly compressible lactose
21; DCPD=Dicalcium phosphate dihydrate; DCP=Dicalcium phosphate; TCP=Tricalcium
Phosphate
Hardness, Friability and Disintegration of tablet
The hardness, friability and disintegration time of tablets prepared from selected batches of
mixture as per good flow properties are shown in table 2. It is surprisingly to know that each
excipient shows different hardness, friability and disintegration time with direct compression and
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dry granulation method. Tablets produced should possess more than 40N hardness and friability
should not be more than 1% as USP. Excipients which shows good flow properties and good
hardness with the drug are further selected for the compressibility and compactibility studies.
Table 2: Hardness, Friability and Disintegration time of tablets produced from selected
batches of direct compression method
Batch No Excipient Hardness
(Newton)
N=5
Friability
(%)
Disintegration
time (min)
N=5
SAT3 Avicel PH 102 119 7 0.49 1 1
SAT6 Avicel PH 200 108 5 0.64 1 1
SAT9 DCL 21 154 5 0.31 1 1
SAT15 Starch-1500 52 6 Tablet breaks -
SAT18 DCP 57 4 Tablet breaks -
SAT21 TCP 98 8 0.71 1 1
Table 3: Flow properties of tableting mixture prepared by dry granulation method
Batch No Excipient AOR
(º)
Bulk
Density
(gm/cm3)
Tapped
density
(gm/cm3)
Carr’s
Index
(%)
Flow
properties
SATD1 MCC IP 33.74 1.3 0.860.4 0.950.3 11.62 Good
SATD2 LM 32.54 0.9 0.80 0.3 0.95 0.2 18.75 Good
SATD3 DCPD 31.13 1.5 0.71 0.3 0.95 0.2 25.00 Good
SATD4 TCP 34.21 1.1 0.74 0.3 0.86 0.3 16.21 Good
* Each batch contains excipients (325mg); sarpagandharoot powder (325mg); crosscarmellose
sodium (5%); talc (2%), and magnesium stearate (1%).
Table 4: Hardness, Friability and Disintegration time of tablets prepared by dry
granulation method
Batch No Excipient Hardness
(Newton)
N=5
Friability
(%)
Disintegration time
(min)
N=5
SATD1 MCC IP 60 8 0.28 1 1
SATD2 LM 71 5 0.37 1 1
SATD3 DCPD 117 10 0.19 1 1
SATD4 TCP 82 9 0.44 1 1
*Batches were selected based on Hardness and Friability acceptability criteria.
Compressibility
Compressibility is the ability to deform under pressure. The compressibility profile of DCL
21/Avicel PH 200 for direct compression and TCP for dry granulation showed the highest
porosity compared to other materials as well as the smallest changes in porosity over the
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compression pressure range, implying that it has the better compressibility. On the other side,
DCL 21 for direct compression and DCPD and LM for dry granulation showed more comparable
porosity profiles.
Heckal plot
Table 5: compressibility of tableting mixture studied using the heckel plot, where k
represents the heckel coefficient and Py, yield pressure; DC=Direct compression, DG= Dry
granulation
Figure 1: Comparison of Heckel plot (Direct compression)
0
1
2
3
4
5
6
0 0.5 1 1.5 2 2.5 3 3.5
ln(1
/)
Pressure in ton
Comparision of Heckel plot(sarpagandga direct compression)
Avicel PH 102 Avicel PH 200 DCL 21 TCP
Batch No Material R2 k
(Heckel co-
efficient)
Yield Pressure (Py)
(ton)
SAT 3 (DC) Avicel PH 102 0.841 1.0096 0.9904
SAT 6 (DC) Avicel PH 200 0.941 1.4845 0.6736
SAT 9 (DC) DCL 21 0.863 1.0015 0.9985
SAT 21 (DC) TCP 0.829 0.9144 1.0936
SATD 1 (DG) MCC IP 0.942 1.1876 0.8420
SATD 2 (DG) LM 0.910 1.0422 0.9542
SATD 3 (DG) DCPD 0.883 0.8769 1.1403
SATD 4 (DG) TCP 0.944 1.4082 0.7101
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Figure 2: Comparison of Heckel plot (Dry granulation)
Table 6: Comparison of Results of the Heckel co-efficient (k) and Walker co-efficient (W’)
Batch No Excipient k W’ * 100 (%)
SAT 3 (DC) Avicel PH 102 1.0096 126.6
SAT 6 (DC) Avicel PH 200 1.4845 149.6
SAT 9 (DC) DCL 21 1.0015 145.8
SAT 21 (DC) TCP 0.9144 97.2
SATD 1 (DG) MCC IP 1.1876 83.41
SATD 2 (DG) LM 1.0479 84.7
SATD 3 (DG) DCPD 0.8769 68.9
SATD 4 (DG) TCP 1.4082 94.9
Considering the heckel co-efficient, material compressibility decreases in the following
order,Avicel PH 200>Avicel PH 102>DCL 21>TCP in case of direct compression. In case of dry
granulation, the compressibility order was found: DCPD>LM>MCC IP>TCP. A similar trend
was found in the Walker Co-efficient. Higher values of w’ and k are indicators of a better
compressibility (plasticity) of the powder.
The direct mixtures compressibility, is comparable with that of the dry granulation mixtures,
most certainly lies as the choice of input raw materials that are themselves originally suitable for
direct tableting. Mixture of direct compressible excipient shows even better compressibility than
that of single directly compressible excipient. The lower compressibility of dry granulated
mixture maybe partly attributed to double particle processing. In the slugging process and
0
1
2
3
4
5
6
0 0.5 1 1.5 2 2.5 3 3.5
ln (
1/
)
Pressure in ton
Comparision of Heckel plot(sarpagandha dry granulation)
MCC IP DCPD TCP LM
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compacting, particles are milled and compressed using the dry granulation step and
recompressed during tableting. The reduction in the dry granulated mixtures compressibility may
be attributed to work hardening.[11]
Walker analysis
The walker plots is described by inverse of pressure versus specific volume. The walker model
once again proved that the most compressible mixture is the tableting mixture containing
sarpagandha root powder with Avicel PH 200 with w’ of 149.6 for direct compression. For dry
granulation, most compressible mixture was found to be the mixture containing TCP with the
value of w’ of 94.98. The results of walker analysis was found according to the pattern of
Heckel’s plot. It is important to emphasize that the walker model’s has slightly better
discriminative power over the heckel’s model to differentiate tableting mixture compressibility.
Table 7: Compressibility of tableting mixture studied according to the Walker model
Batch No Excipient w’ * 100 (%) R2
SAT 3 (DC) Avicel PH 102 126.6 0.9846
SAT 6 (DC) Avicel PH 200 149.6 0.8439
SAT 9 (DC) DCL 21 145.8 0.9826
SAT 21 (DC) TCP 97.2 0.9809
SATD 1 (DG) MCC IP 83.41 0.9542
SATD 2 (DG) LM 84.78 0.974
SATD 3 (DG) DCPD 68.95 0.9361
SATD 4 (DG) TCP 94.98 0.9994
Figure 3: Comparison of Walker analysis (Direct compression)
0
100
200
300
400
500
600
700
800
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5
Spec
ific
vo
lum
e
log P
Comparision of walker analysis(Sarpagandha direct compression)
Avicel PH 102 Avicel PH 200 DCL 21 TCP
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Figure 4: Comparison of Walker analysis (Dry granulation)
Compactibility
Compactibility is the materials ability to produce tablets of sufficient mechanical strength under
the pressure applied. The mechanical strength of the compact associated with the number of
contacts point generated. The compactibility of a specific substance can be represented by a plot
of tensile strength versus compression pressure or by the compactibility co-efficient (Cp) which
is determined as the slope of the linear regression line of tensile strength versus compression
pressure. Therefore a higher value of (Cp) means that with increasing compression pressure the
tensile strength of the compact increases faster in comparison to materials with lower (Cp). [13]
Compactibility of the materials is accessed by compactibility coefficients (Cp) which are
presented in table 8.
According to (Cp) the compactibility of excipients decreases in the following order for direct
compression: Avicel PH 200>DCL 21>TCP>Avicel PH 102for Dry granulation:
TCP>DCPD>LM>MCC IP.
Table 8: Compactibility co-efficient (Cp) of excipients studied
Batch No Excipient Cp* 101 R2
SAT 3 (DC) Avicel PH 102 (DC) 7.11 0.996
SAT 6 (DC) Avicel PH 200 (DC) 8 0.994
SAT 9 (DC) DCL 21 (DC) 7.8 0.996
SAT 21 (DC) TCP (DC) 7.23 0.993
SATD 1 (DG) MCC IP (DG) 6.06 0.984
SATD 2 (DG) LM (DG) 6.38 0.989
SATD 3 (DG) DCPD (DG) 6.84 0.994
SATD 4 (DG) TCP (DG) 7.6 0.997
0
200
400
600
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5
Spec
ific
vo
lum
e
log P
Comparision of Walker analysis(Sarpagandha Dry granulation)
MCC IP DCPD TCP LM
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Figure 5: Compactibility profile of excipients
Kawakita’s equation
Table 9: Values of 1/a, a/ab, a and b for various excipient
Avicel
PH 102
Avicel
PH 200
DCL
21
TCP MCC
IP
LM DCPD TCP
1/a 4.616 5.126 1.976 1.909 2.775 2.488 2.463 3.113
1/ab 44.23 13.19 14.216 15.026 7.68 4.34 14.29 4.34
a 0.217 0.195 0.506 0.5248 0.360 0.402 0.406 0.321
b 0.104 0.388 0.140 0.127 0.361 0.573 0.172 0.718
*Slope = 1/a Intercept = 1/ab
The packability of agglomerates of the tableting mixture was ascertained by comparing the
constants a, b and k in Kawakita’s and Kuno’s equations, respectively. The constant ‘a’
represents the proportion of consolidation as closest packing is attained. The reciprocal of b and
k represents the packing velocity. The constant ‘a’ for the direct compression tableting mixture
containing Avicel PH 200 has smaller value than the others and for dry granulation TCP has
smaller value than other two excipients.[14] The results indicate that the agglomerates showed
good packing even without tapping. The large value of b for the direct compression of Avicel PH
200 and for the dry granulation Tproved that the packing velocity of these excipient and drug by
tapping was slower than that of the other excipients.
0
0.5
1
1.5
2
2.5
0 0.5 1 1.5 2 2.5 3 3.5
Ten
sile
str
engt
h (
TON
)
Compression pressure (TON)
MCC102 MCC 200 DCL TCP
MCC IP Lactose monohydrate DCPD TCP
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Kuno’s equation
Table 10: values of k for different excipient
Avicel
PH 102
Avicel
PH 200
DCL 21 TCP MCC IP LM DCPD TCP
k 0.01 0.006 0.001 0.009 0.05 0.07 0.02 0.01
The values of ‘k’ from kuno’s equation for the tableting mixtures were shown in table 10. The
slow packing velocity corresponds with proportion of the consolidation of the powder bed per
tap. The Avicel PH 200 for direct compression and TCP for dry granulation showed comparable
compression properties as compared with other excipients.
Elastic recovery
Plasticity and fragmentation are desirable deformational properties for compaction. On the other
hand, elastic deformation is undesirable because it hinders the formation of coherent tablets.
Fragmentation and plastic deformation are considered to be strength-producing compression
mechanisms whereas elastic deformation is considered to be a disruptive rather than bond-
forming mechanism. Fragmentation is suggested to increase the strength by the large number of
contact sites between particles at which bonds can be formed. For plastic deformation, the
increased bonding force is usually explained as an effect of increased contact area at the
interparticulate contact site. Plasticity is more expressed in the case of mixture of Avicel PH 200
for direct compression and TCP for dry granulation. It can be assumed that the material is brittle
with minimal plasticity.
The elastic deformation results expressed as an index of elastic relaxation are presented in table
11. For the directly compressible tableting mixture, elasticity decreases in following order:
tableting mixture containing Avicel PH 200>TCP>DCL 21>Avicel PH 102, and for dry
granulation method TCP>LM>MCC>LM. According to Py value, the material is considered soft
when the value is below 0.92 ton, moderately hard when the value is between 0.93 and 2.30 ton
and hard when the value is higher than the 2.30 ton.[13] Therefore elastic relaxation index were
used to describe materials deformational properties. The results are summarized in table 12.
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Table 11: Elastic relaxation for excipient studied
Batch No Drug + Excipient Elastic recovery (%)
AVG SD
SAT 3 (DC) Avicel PH 102 0.74 0.09
SAT 6 (DC) Avicel PH 200 0.21 0.06
SAT 9 (DC) DCL 21 0.37 0.05
SAT 21 (DC) TCP 0.24 0.10
SATD 1 (DG) MCC IP 0.22 0.06
SATD 2 (DG) LM 0.21 0.07
SATD 3 (DG) DCPD 0.33 0.04
SATD 4 (DG) TCP 0.19 0.03
Table 12: Assessment of the deformational properties of tableting mixture determined as
the bulk level using yield pressure (Py), obtained from the Heckel co-efficient and elastic
relaxation
Batch No Excipient Py (ton) Plasticity ER Elasticity
SAT 3 (DC) MCC 102 (DC) 0.9904 Moderately soft 0.74 0.09 Medium
SAT 6 (DC) MCC 200 (DC) 0.6736 Soft 0.21 0.06 High
SAT 9 (DC) DCL 21 (DC) 0.9985 Moderately soft 0.37 0.05 Medium
SAT 21 (DC) TCP (DC) 1.0936 Moderately soft 0.24 0.10 Medium
SATD 1 (DG) MCC IP (DG) 0.8420 Soft 0.22 0.06 High
SATD 2 (DG) LM (DG) 0.9542 Moderately soft 0.21 0.07 Medium
SATD 3 (DG) DCPD (DG) 1.1403 Moderately soft 0.33 0.04 Medium
SATD 4 (DG) TCP (DG) 0.7101 soft 0.19 0.03 High
CONCLUSION
Various excipients have a great influence on the compressibility and compactibility process. In
order to determine best excipient for the drug, tableting mixture containing drug with excipient
was precisely characterized. For, direct compression method the most compressible excipient for
preparation of sarpagandha tablet was found to be mixture of Avicel PH 200 and for dry
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Arpit et al. / Pharma Science Monitor 8(2), Apr-Jun 2017, 338-353
granulation it was TCP. Further, tableting mixtures containing these excipients showed good
flow properties along with acceptable hardness and disintegration time. Both, the Heckel plots
and walker analysis showed the same result. Kawakita’s and kuno’s equation showed that these
tableting mixtures has smaller value of ‘a’ and large value of ‘b’, than other tableting mixtures
indicating that, they can be easily compacted without the tapping.
ACKNOWLEDGMENT
We are thankful to Intas Pharmaceuticals Ltd; Ahmedabad for sending us gift samples of directly
compressible lactose (DCL 21), starch-1500, microcrystalline cellulose (Avicel PH-102, Avicel
PH-200).
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