Formulation of liquisolid compact:Liquid vehicle: Liquid vehicle used in liquisolid systemsshould be orally safe, inert, not highly viscous, and preferably water-misciblenonvolatile high boiling point organic solvents, such as propylene glycol,glycerin, PEG 200 and 400, polysorbate 20 and 80, etc.5Carrier material: These are as porous substance possessingadequate absorption properties.1 As carriers allow an incorporationof large amount of liquid medication into the liquisolid structure, theproperties of carriers, such as (SSA) and liquid absorption capacity, are ofgreat importance in designing the formulation of liquisolid system. 5 Thecarrier materials are used for liquisolid compact preparation are Avicel PH102,microcrystallinecellulose, Eudragit L-100, Eudragit RS-100, 1,5 Coating material: Coating materials refer to very fine andhighly adsorptive materials,such as Aerosil® 200, Neusilin®, and calciumsilicate or magnesium aluminometasilicates in a powder form.5Additives :Disintegrants: These are used to break thecompacts to smaller particles. e.g: Crosscarmellose sodium, Crosspovidone,Explotab and Pre-gelatinized starch etc.Lubricants: These are intended to reduce thefriction.
e.g: Stearic acid, Stearic acid salts and Talc etc. Glidants: Intended to promote the flowbetween particles by reducing the friction.
e.g: Silica derivatives, Talc andCorn starch etc. 7General method ofpreparation of liquisolid compact:First step in which weigh the calculated amountof drug and dissolved in a suitable solvent. The liquid solution incorporate onto the carrier material blend it properly .then add the coating material inphysical mixture keep it for 5 min. for proper adsorption of coating an carriermaterial. And the mixture used for encapsulation and direct compression.
5, 6 Fig. Fig.2.shows General method ofliquisolid compact preparation, fig adapted from reference no 7.Evaluation ofliquisolid compact:Evaluationof flow properties The formulations were evaluated forthe 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 themaximum angle possible between the surface of a pile of powder and thehorizontal plane. Thus, r being the radius of the base of the conical pile . Tan?= (h/r) . Bulk density: Bulk density refers to the measureused to describe a packing of particles. Bulk density is defined as the mass ofpowder divided by the bulk volume.
?b =M / Vb .Tapped density: Tapped density can be defined asmass of blend in the measuring cylinder divided by its tapped volume. ?t = M / Vt 10Carr’s compressibility index The compressibility index (Carr’sindex) 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 = tappeddensity/bulk density11Evaluation of liquisolid tabletPrepared tablets were subjected to evaluationof different properties including drug content uniformity, weight variation,tablet hardness, friability, tablet dimensions, disintegration time test, and invitro drug release.12Tablet dimensions Thickness and diameter were measured using vernier caliper. Threetablets from each form ulation were used, and average values werecalculated.
12Hardness Test: 10tablets were selected and the hardness was tested using Monsanto tester.”Hardness factor”, the average of six determinations, was determined.13Friability Test: Rochefriabilator was used to measure the friability of the tablet. 13Content uniformity:10tablets were crushed and an accurately weighed amount of powder equivalent tounit 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.
Eachstudy was carried out in triplicate, and mean data were recorded.14 Uniformity of weight 20 tablets from each formulation batch were individually weighed andthe mean weight was calculated. Percentage weight variation was calculated foreach batch.14 Disintegrationtest:The disintegration time was determined inDisintegration apparatus with a basket rack assembly containing six open-endedtubes and 10-mesh screen on the bottom was used. A tablet was placed in eachtube of the basket and the time for complete disintegration ofthe six tablets wasrecorded.
13In vitro dissolution studies of liquisolidtablet: The USPpaddle method used for all the in vitro dissolution studies. In thismethod, simulated gastric fluid (pH 1.2), and intestinal fluid (pH 6.8) withoutenzyme were used as dissolution media. The rate ofstirring was 50+/- 2 rpm.
Theamount of piroxicam was 10 mg in all formulations. The dosage forms wereplaced in 900 mL of gastric fluid (HCl solution) or intestinal fluid (phosphatebuffer) 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 filteredthrough a 0.45-mm Millipore filter.
15Scanningelectron microscopy (SEM) SEM isutilized to assess the morphological characteristics of the raw materials andthe drug carrier systems.16FTIR (flurier transform electron microscopy):In the preparation ofliquisolid Tablets, Felodipine and excipients may interact as they are in closecontact with each other, which could lead to the instability of drug. FTIRSpectroscopy was employed to ascertain the compatibility between Felodipine andexcipients17 Differential Scanning Calorimetry (DSC)DSC use for stability study. It determines the drugexcipeants interaction The drug has a characteristic peak, absence of this peakin DSC thermogram indicates that the drug is in the form of solution in liquidformulation and it is molecularly dispersed within the system . 7Conclusion: Poorly soluble drugs has a problem relatedwith the bioavailability and dissolution.
Low solubility create problem informulation development. The liquisolid compact is the successful tool forenhance solubility solubility and dissolution rate. It is promising tool forligh loading dose of drug by using suitable carrier. We can formulate good flowand good compaction property liquisolid compact formula