Experimental Work Preformulation Studies Biology Essay


Preformulation may be described as platform of development during the physicochemical and biopharmaceutical properties of a drug substance are characterized. It is an important part of the drug development process. The information relating to drug development acquired during this phase is used for making critical decisions in subsequent stages of development. A wide variety of information must be generated to develop formulations rationally. Characterization of the drug is important step in Preformulation phase of product development followed by studying the properties of the excipient and their compatibility.

Physicochemical Evaluation of both the Drugs:

The drug was physically characterized according to following methods;

Organoleptic evaluation of:

Nature of the drug sample:

The both the drug sample was observed visually and viewed under the compound microscope for the determination of its nature and then the results were compared with the official books and United States Pharmacopoeia.

Color of the drug sample:

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The drug sample was viewed visually for the determination of its color using the black and white backgrounds and then the results were compared with the official books and United States Pharmacopoeia.

Identification of the Drug Sample.


The FTIR spectrum of API was recorded by using FT-IR spectroscopy (Shimadzu, FTIR-8400 S). The IR absorption spectra of pure drug was taken in the range of 4000-500cm-1 using KBr disc method (Schimadzu FTIR 8400 S) and the characteristic peaks of drug were observed.

By UV Spectrophotometry:

100 mg of the drug was dissolved in a few ml of methanol and then was made up to 100 ml with Phosphate buffer pH 6.8 + 6% SLS. This stock solution was further diluted to get a concentration of 5 ppm.This solution was scanned in a wavelength of 200 to 400 nm by using UV Spectrophotometry.


Scanning of the drug by UV Spectrophotometry:

In pH 6.8 phosphate buffer :

100 mg of the drug was dissolved in a few ml of methanol and then was made up to 100 ml with PH 6.8 phosphate buffer+ 6% SLS. This stock solution was further diluted to get a concentration of 5 ppm. This solution was then scanned in a wavelength range of 200 to 400 nm using a UV Spectrophotometer.

Preparation of the Standard Curves in phosphate buffer + 6% SLS (pH - 6.8):

10 mg of the drug was weighed accurately and dissolved in a few ml of methanol and phosphate buffer + 6% SLS then was made up to 100 ml with the same. This stock solution was further diluted to get solutions of various concentrations viz 1, 2, 3, 4 & 5 for API-1 the corresponding absorbance were read at 285.0 nm respectively using a UV Spectrophotometer.


The IR absorption spectra of the pure drug and physical admixtures of drug with various excipients were taken in the range of 4000-500 cm-1 using KBr disc method (Schimadzu IR- Prestige-21) and observed for characteristic peaks of drug.

According to the functional category these excipients were mixed in different ratios with drug. 1 gram of blend size was taken for the ratio calculation. These mixtures were kept in 40°C / 75 %RH and 60°C, in a 2-ml closed glass vial in exposed condition for 1 month. After 4 weeks, the samples were withdrawn and analyzed.


Step -1

Dispensing: Carryout the dispensing of the active pharmaceutical ingredient and excipients in dispensing booth as per manufacturing formula.

Step -2

Sifting: Sift API ,Lactose monohydrate, Kollidone SR, through # 40.


Mixing: Transfer the sifted material of Step II into a virgin polybag and mix it well.


Binder addition; PVP-K 25 and DM water required quantity.


Drying : dry the granules in hot air oven up to % 1.5to 2.5 LOD maintain .


Lubrication: Sift Magnesium Strearate through 60# and transfer the Lubricating material i.e. magnesium stearate into the pre lubricated material of Step-5 and blend for 5 minutes


Compression: Compress the lubricated material of step-6 in 8 station Compression machine using 19 Ã- 9 mm punches


Angle of repose:

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The angle of repose is in which the maximum angle that the plane of powder makes the horizontal surface on rotation. Angle of repose is helpful in assessment of flow properties of particles which could be further related to packing densities and mechanical arrangements of particles.

The granules weighed accurately taken in a funnel. The height of funnel adjusted in such a way that the tip of the funnel just touched the apex of the heap of granules. The granules allowed to flow through funnel freely onto the surface. The diameter of powder cone was measured and angle of repose calculated using the following equation.

tan θ = h/r

Where, h = height of the powder heap

r = radius of the powder heap

θ = is the angle of repose.

Angle of Repose

S. No.

Angle of repose

Flow property













Determination of Bulk Density and Tapped Density:

Bulk density of a compound differs with the method of crystallization, milling and formulation. It is of great importance when one considers the size of a high - dose capsule product or the homogeneity of a low dose formulation in which there are large differences in drug and excipient densities. In addition to bulk density, it is frequently desirable to know the true density of a powder for computation of void volume or porosity of packed powder beds.

Accurately weighed quantity of granules (W) poured into graduated cylinder and volume (V0) is measured. Then the cylinder is closed with a lid and set into the tap density tester (USP). The density apparatus was set for 500 taps after 750 taps and the volume (Vf) is measured and continue process until the two consecutive readings are equal. Bulk density and tapped density is calculated using the following formulae.

Bulk density is =W/V0

Tapped density is =W/V


W is =Weight of the powder,

V0 is =Initial volume

Vf is =final volume

Carr's Compressibility Index:

The indirect method of measuring powder flow from bulk densities is developed by Carr. The % compressibility of a powder is a direct measure of the potential powder arch or bridge strength and stability. Carr's index of every formulation is calculated according to equation,

Carr's Compressibility Index (%) = [(TD-BD) X 100] / TD


TD = Tapped density

BD = bulk density

Table 8.2 Relationships between % Compressibility and Flow ability:

Sl. No.


Flow ability


5 - 15



12 - 16



18 - 21

Fair to Passable


23 - 35



33 - 38

Very Poor


> 40

Extremely Poor

Hausner's Ratio:

Hausner's Ratio tells the flow properties of powder and is measured by the ratio of tapped density to bulk density. It is the ratio of tapped density and bulk density.Hausner finds that this ratio is related to interparticle friction and, as such, could be used to predict powder flow properties. Generally a value less than 1.25 indicates good flow properties, which is equivalent to 20 percent of Carr's index.

Hausner's Ratio = Tapped density / Bulk Density

Table 8.3 Significance of Hausner's ratio

Sr. No.

Hausner's Ratio




Free flowing



Cohesive powder


Hardness test:

A Tablet requires a certain amount of strength or hardness and resistance to friability to withstand mechanical shock of handling in manufacture, packing and shipping. Hardness tester measured the hardness of tablet. Five tablets from each batch were used for hardness studies and results were expressed in Newton.

Thickness, diameter:

Thickness and diameter of tablets is carried out by using vernier caliper. 5 tablets were used for the above test from each batch results were expressed in millimeter.

Weight variation test:

20 tablets should be selected in random, separately as single tablet weighed in a single pan electronic balance and average weight is calculated. The uniformity of weight was calculated. The uniformity of weight is determined according to USP specification. As per USP not more than 2 of individual weight should deviate from average weight by more than 5% and none deviate more than twice the percentage.

Friability test:

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In Roche friabilator apparatus the tablets were subjected to the combined effect of abrasion and shock by utilizing a plastic chamber that revolve at 25 rpm dropping the tablets at a distance of six inches with each revolution. Preweighed samples of 20 tablets are placed in the Friabilator, then operated for 100 revolutions. Tablets are then dusted and reweighed. Conventional compressed tablets that loss than less than 0.5 to 1.0% of their weight are generally considered acceptable.

% F = {1-(Wt/W)} Ã-100


% F = Friability in percentage

W = Initial weight of tablets

Wt = Weight of tablets after revolution

Assay of tablets:

20 randomly taken tablets from each formulation are thinly powdered in a mortar and a portion of the obtaining powder equal to the weight of the respective tablet is solubilized in few ml of methanol and then add phosphate buffer in 100ml volumetric flask and then diluted with phosphate buffer to make a solution of API -1 as per the standard concentration of calibration curve and assayed spectrophotometrically at 285 nm. Each measurement was carried out in triplicate and the results were averaged. Blank solution containing all the components, except for drug, was also prepared.

Dissolution studies (Invitro):-

The release rate of API-1 from chewable tablets was determined. The dissolution test was performed using United States Pharmacopoeia (USP) type II (Paddle) apparatus, 900 ml of phosphate buffer PH -6.8+ 6%SLS at 37 ± 0.5°C and 50 rpm. A sample of the solution was withdrawn from the dissolution apparatus at the appropriate time for 60 minutes, and the samples were replaced with fresh dissolution medium. The samples were diluted into a suitable concentration with phosphate buffer PH -6.8+ 6% SLS. Absorbance of these solutions was measured at 285 nm using a Shimadzu UV/Visible double-beam spectrophotometer. Cumulative percentage drug release was calculated. The drug content was calculated using the simultaneously equation. The % cumulative drug release was calculated.

Details of dissolution test:

Dissolution test apparatus : USP II

Speed : 50±0.1 rpm

Stirrer : Paddle type

Volume of medium : 900 ml

Time interval : 1, 2, 4, 6, 8, 10, 12 and 14 hours.

Medium used : phosphate buffer, PH -6.8+ 6%SLS

Temperature : 37 ± 0.5 0C