Formulation of great importance in designing the formulation of

Formulation of liquisolid compact:

Liquid vehicle: Liquid vehicle used in liquisolid systems
should be orally safe, inert, not highly viscous, and preferably water-miscible
nonvolatile high boiling point organic solvents, such as propylene glycol,
glycerin, PEG 200 and 400, polysorbate 20 and 80, etc.5

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Carrier material: These are as porous substance possessing
adequate absorption properties.1 As carriers allow an incorporation
of large amount of liquid medication into the liquisolid structure, the
properties of carriers, such as (SSA) and liquid absorption capacity, are of
great importance in designing the formulation of liquisolid system. 5 The
carrier materials are used for liquisolid compact preparation are Avicel PH102,microcrystalline
cellulose, Eudragit L-100, Eudragit RS-100, 1,5

Coating material: Coating materials refer to very fine and
highly adsorptive materials,

such as Aerosil® 200, Neusilin®, and calcium
silicate or magnesium aluminometasilicates in a powder form.5

Additives :

Disintegrants: These are used to break the
compacts to smaller particles. e.g: Crosscarmellose sodium, Crosspovidone,
Explotab and Pre-gelatinized starch etc.

Lubricants: These are intended to reduce the
friction. e.g: Stearic acid, Stearic acid salts and Talc etc.

 

Glidants: Intended to promote the flow
between particles by reducing the friction. e.g: Silica derivatives, Talc and
Corn starch etc. 7

General method of
preparation of liquisolid compact:

First step in which weigh the calculated amount
of drug and dissolved in a suitable solvent. The liquid solution incorporate on
to the carrier material blend it properly .then add the coating material in
physical mixture keep it for 5 min. for proper adsorption of coating an carrier
material. And the mixture used for encapsulation and direct compression. 5, 6 Fig. Fig.2.shows General method of
liquisolid compact preparation, fig adapted from reference no 7.

Evaluation of
liquisolid compact:

Evaluation
of flow properties

The formulations were evaluated for
the following properties such as angle of repose, bulk density, tapped density,
Hausner’s ratio, Carr’s index.
9

 Angle of repose: Angle of repose was measured by fixed funnel method. This is the
maximum angle possible between the surface of a pile of powder and the
horizontal plane. Thus, r being the radius of the base of the conical pile .

Tan?= (h/r) .

Bulk density: Bulk density refers to the measure
used to describe a packing of particles. Bulk density is defined as the mass of
powder divided by the bulk volume.

 ?b =
M / Vb .

Tapped density: Tapped density can be defined as
mass of blend in the measuring cylinder divided by its tapped volume.

?t = M / Vt 10

Carr’s compressibility index

 

The compressibility index (Carr’s
index) is a measures the tendency of a powder to be compressed.

Carr’s index (%) = (tapped density
? bulk density) × 100/ tapped density

Hausner’s ratio

Hausner’s ratio = tapped
density/bulk density11

Evaluation of liquisolid tablet

Prepared tablets were subjected to evaluation
of different properties including drug content uniformity, weight variation,
tablet hardness, friability, tablet dimensions, disintegration time test, and in
vitro drug release.12

Tablet dimensions

Thickness and diameter were measured using vernier caliper. Three
tablets from each form ulation were used, and average values were
calculated. 12

Hardness Test: 10
tablets were selected and the hardness was tested using Monsanto tester.
“Hardness factor”, the average of six determinations, was determined.13

Friability Test: Roche
friabilator was used to measure the friability of the tablet. 13

Content 
uniformity:

10
tablets were crushed and an accurately weighed amount of powder equivalent to
unit dose of a single tablet. This was dissolved in 100 ml suitable solvents,
subjected to sonication and then filtered through a membrane filter (Millipore,
0.45 ?m pore size). The drug content was determined by HPLC analysis. Each
study was carried out in triplicate, and mean data were recorded.14

 

Uniformity of weight

20 tablets from each formulation batch were individually weighed and
the mean weight was calculated. Percentage weight variation was calculated for
each batch.14

Disintegration
test:

The disintegration time was determined in
Disintegration apparatus with a basket rack assembly containing six open-ended
tubes and 10-mesh screen on the bottom was used. A tablet was placed in each
tube of the basket and the time for complete disintegration of

the six tablets was
recorded. 13

In vitro dissolution studies of liquisolid
tablet:

 The USP
paddle method used for all the in vitro dissolution studies. In this
method, simulated gastric fluid (pH 1.2), and intestinal fluid (pH 6.8) without
enzyme were used as dissolution media. The rate ofstirring was 50+/- 2 rpm. The
amount of piroxicam was 10 mg in all formulations. The dosage forms were
placed in 900 mL of gastric fluid (HCl solution) or intestinal fluid (phosphate
buffer) and maintained at 37 +/- 0.1°C. At appropriate intervals (5, 10, 20,
30, 40, 50, 60, and 70 min), 5 mL of the samples were taken and filtered
through a 0.45-mm Millipore filter.15

Scanning
electron microscopy (SEM)

 SEM is
utilized to assess the morphological characteristics of the raw materials and
the drug carrier systems.16

FTIR (flurier transform electron microscopy):

In the preparation of
liquisolid Tablets, Felodipine and excipients may interact as they are in close
contact with each other, which could lead to the instability of drug. FTIR
Spectroscopy was employed to ascertain the compatibility between Felodipine and
excipients17

 

 Differential Scanning Calorimetry (DSC)

DSC use for stability study. It determines the drug
excipeants interaction The drug has a characteristic peak, absence of this peak
in DSC thermogram indicates that the drug is in the form of solution in liquid
formulation and it is molecularly dispersed within the system . 7

Conclusion:

 Poorly soluble drugs has a problem related
with the bioavailability and dissolution. Low solubility create problem in
formulation development. The liquisolid compact is the successful tool for
enhance solubility solubility and dissolution rate. It is promising tool for
ligh loading dose of drug by using suitable carrier. We can formulate good flow
and good compaction property liquisolid compact formula

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