Physiochemical Properties Of Excipients Biology Essay

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Xanthan gum used both in oral, topical pharmaceutical preparations, cosmetics, and foods as suspending, stabilizing agent. It is used as a thickening and emulsifying agent. It is nontoxic, compatible with many other pharmaceutical ingredients, and it has good stability and viscosity properties in a wide pH and temperature range; . Xanthan gum gels show pseudo plastic behavior, the shear thinning directly proportional to the shear rate. The viscosity returns to normal immediately on release of shear stress.

When xanthan gum is mixed with inorganic suspending agents, such as magnesium aluminum silicate, or organic gums, synergistic rheological effects occur. In general, mixtures of xanthan gum and magnesium aluminum silicate in ratios between 1 : 2 and 1 : 9 produce the optimum properties. Similarly, optimum synergistic effects are obtained with xanthan gum : guar gum ratios between 3 : 7 and 1 : 9.

Although primarily used as a suspending agent, xanthan gum has also been used to prepare sustained-release matrix tablets.

Xanthan gum has been incorporated in an ophthalmic liquids, it interacts with mucin, helping in the prolonged retention of dosage form in the pre corneal area. xanthan gum is also used as an excipient for spray-drying and freeze-drying processes for better results. Xanthan gum is used to increase the bioadhesive strength in vaginal formulations and acts as a binder in colon specific drug delivery systems. Xanthan gum is also used in cosmetics and used as a thickening agent in shampoo.


Xanthan gum can be find as a cream- or white-colored, odorless, free-flowing, fine powder.

Particle size distribution: Different grades with different particle sizes are available; for example, 100% less than 180 Î¼m in size for Keltrol CG; 100% less than 75 Î¼m in size for Keltrol CGF; 100% less than 250 Î¼m, 95% less than 177 Î¼m in size for Rhodigel; 100% less than 177 Î¼m, 92% less than 74 Î¼m in size for Rhodigel 200.


  Partially insoluble in ethanol and ether; soluble in cold or warm water.

Viscosity (dynamic):

1200-1600 mPa s (1200-1600 cP) for a 1% w/v aqueous solution at 25°C.

Stability and Storage Conditions:

Aqueous solutions are stable at a wide pH range (pH 3-12), although they has maximum stability at pH 4-10 and temperatures of 10-60°C. Xanthan gum solutions of less than 1% w/v concentration adversely affected by higher than ambient temperatures: for example, viscosity will be reduced. Solutions also stable in the presence of enzymes, salts, acids, and bases. The bulk materials should store in a well-closed container in a cool, dry place.

Lactose, Monohydrate


Lactochem Coarse Crystals, Pharmatose DCL 15, NF Lactose 310

Chemical Name and CAS Registry Number:-

O-β-D-Galactopyranosyl-(1→4)-α-D-glucopyranose monohydrate [64044-51-5]

Structural Formula:-

Functional Category:-

Binding agent; diluents for dry-powder inhalers; tablet binder; tablet and capsule diluents.

Applications in Pharmaceutical Formulation:-

Lactose is used as a filler or diluents in tablets and capsules, and has a limited involve in lyophilized products and infant formulas. Lactose is also used as diluents in dry-powder inhalation. Lactose available commercially has different physical properties as particle size distribution and flow characteristics.

Lactose added to freeze-dried solutions to increase plug size and aid cohesion. It is also used in combination with sucrose (approximately 1: 3) to prepare sugar-coating solutions.


Lactose shows as various isomeric forms, depending on the crystallization and drying conditions, i.e. α-lactose monohydrate, β-lactose anhydrous and α-lactose anhydrous. The stable crystalline forms of lactose are α-lactose monohydrate, β-lactose anhydrous and stable α-lactose anhydrous.

Lactose available in white to off-white crystalline particles or powder. It is odorless and slightly sweet-tasting; α-lactose is approximately 20% as sweet as sucrose, while β-lactose is 40% as sweet.

Stability and Storage Conditions:-

There may be occurrence of mold growth under humid conditions (80% relative humidity and above). Lactose may develop brown coloration on storage; it may be due to increased by warm, damp conditions. The purity of different lactose's can vary and color evaluation may be important, if white tablets are being formulated.


Sometimes Mail lard-type condensation reaction is likely to occur in between lactose and compounds with a primary amine group forms brown or yellow-brown-colored products. Lactose incompatible with amino acids, aminophylline, 19 amfetamines, 20 and Lisinopril2.


Polyox appears white, free-flowing hydrophilic crystalline powders in variety of molecular weights, from one hundred thousand to eight million with an average particle size range around 150 μm. POLYOX NF water-soluble resins have applications in pharmaceutical products, as in controlled release solid dose matrix system, tablet binding, tablet coating, Transdermal drug delivery, and mucosal bioadhesive and gastro-retentive dosage forms.

Common structure:

(-O-CH2-CH2-)n OH. They resemble chemical structure as PEG but have higher molecular weights. n = average number of oxyethylene groups. Ethylene oxide monomer is an epoxide ring. Two corners of this molecule consist of -CH2- linkages In the presence of a catalyst the monomer creates a chain by having the repeat unit -CH2-CH2-O-.

Grades of POLYOX water soluble resins:

POLYOX resins supplied in different molecular weight grades and formulated as NF. The largest level of polyethylene oxide in oral drug form now being used is approximately 543 mg/tablet. 

POLYOX Water-Soluble Resins NF in Pharmaceutical Applications

POLYOX Water-Soluble Resin NF Product number

Approximate Molecular Weight

Viscosity Range at 25°C, cP




WSR N-10


30 - 50



WSR N-80


55 - 90



WSR N-750


600 - 1,200



WSR N-205


4,500 - 8,800



WSR N-1105


8,800 - 17,600






400 - 800





2,000 - 4,000






1,650 - 5,500

WSR Coagulant




5,500 - 7,500





7,500 - 10,000

General properties:

High binding efficiency - POLYOX water-soluble resins have high-binding efficiency for pigments, fillers, and metal powders. Binders easily burn off at low temperatures by little or no tendency to char.

Crosslink ability - POLYOX water-soluble resins cross-linked to form gels which are highly water-retentive.

Film former excipient - POLYOX water-soluble resins forms into flexible films may be prepared by thermoplastic processing and casting techniques. These films may be made of POLYOX water-soluble resins alone or blended by a wide variety of other polymers, like polyethylene, polystyrene, ethylene vinyl acetate, nylon.

Less toxicity - POLYOX, water-soluble resins, have very less toxic in animal studies by all routes. The maximum practical oral dose rates of around 2 g/kg of body weight never had death or signs of toxic observed. Due their high molecular weights, the resins poorly absorbed from the GIT and completely and rapidly excreted. The resins causes' skin irritation nor sensitizers rarely, nor they cause eye irritation as the dry powder or as aqueous solutions.

Flocculent activity - High molecular weight grades of POLYOX water-soluble resins perfectly adsorb onto many colloidal materials and acts as efficient flocculating agents. They show high affinity to a number of materials, like silica, clays, oxidized coal fines, lignin's and paper fines etc.

Lubricity - POLYOX water-soluble resins impart a high degree of lubricity or viscous when contact with water.

Solubility or Thickening of organic solvents - POLYOX water-soluble resins are soluble and will thicken in variety of organic solvents at different temperatures. Organic solvents mostly haloge­nated hydrocarbons, many ketones, alcohols, aromatic hydrocarbons and esters. POLYOX water-soluble resins not soluble in aliphatic hydrocarbon solvents, glycols, diols and aliphatic ethers.

Thickening power (aqueous) - POLYOX h20-soluble resins are nonionic and fully water-soluble at all tempera­tures up to the boiling point of water. POLYOX water-soluble resins are effective thick­ening agents in fresh and salt water. Aqueous solutions are pseudo plastic.

Flow property - All grades of POLYOX water soluble resins flow relatively same. POLYOX contains silica (~1.5%) to help the flow ability.

Applications in Pharmaceutical Industries:

POLYOX use in extended release apps of osmotic pump technologies, hydrophilic matrices, and gastro-retentive dosage formulations and in drug delivery systems such as Transdermal and mucoadhesive technologies.

POLYOX resins also have a number of benefits:

High extent of molecular weights offers formulation flexibility

application in direct compression and granulation

quick hydration and swell for use in osmotic pump technology

rapid hydration and gel development for the use in hydrophilic matrices

Magnesium Stearate

1. Nonproprietary Names

BP: Magnesium stearate

JP: Magnesium stearate

PhEur: Magnesii stearas

USPNF: Magnesium stearate

2. Synonyms

Magnesium octadecanoate; octadecanoic acid, magnesium salt; stearic acid.

4. Empirical Formula & Molecular Weight

C36H70MgO4 591.34

The USPNF 23 defines magnesium stearate as compound of magnesium with a mixture of solid organic acids having variable proportions of magnesium stearate and magnesium palmitate (C32H62MgO4).

5. Structural Formula


6. Functional Category

Tablet, capsule lubricants.

7. Applications in Pharmaceutical Formulation

Magnesium stearate used as cosmetics, foods, and pharmaceutical formulations. Primarily used as lubricant in capsule and tablet manufacture in concentrations between 0.25% and 5.0% w/w.

8. Description

Magnesium stearate is very fine, light white, precipitated or milled, and a faint odor of stearic acid and hey has characteristic taste. The powder is greasy to touch and readily adheres to the skin.

9. Typical Properties


Insoluble in ethanol, ethanol (95%), ether & water; slightly soluble in warm benzene & warm ethanol (95%).

10. Stability and Storage

Magnesium stearates are stable and have to be store in a well-closed container in a cool, dry place.

11. Incompatibilities

Incompatible with strong acids, alkalis, & iron salts. Refrain mixing with strong oxidizing materials. Magnesium stearate shouldn't be used in products containing aspirin, some vitamins, & most alkaloid salts.


Nonproprietary Names

BP: Povidone

JP: Povidone

PhEur: Povidonum

USP: Povidone


E1201; Kollidon; plasdone; poly[1-(2-oxo-1-pyrrolidinyl)ethylene]; polyvidone; polyvinylpyrrolidone; PVP; 1-vinyl-2-pyrrolidinone polymer.

Approximate molecular weights for different grades of Povidone.


Approximate molecular weight


2 500


8 000


10 000


30 000


50 000


400 000


1 000 000


3 000 000

Structural Formula

Functional Category

Disintegrate; dissolution aid; suspending agent; tablet binder.

Applications in Pharmaceutical Formulation

Povidone used in a number of pharmaceutical formulations; it is primarily used in solid-dosage forms. Povidone solutions used as binders in wet-granulation processes. Povidone added to powder blends in dry form and granulated in situ by the adding of water, alcohol, or hydro alcoholic solutions. Povidone used as solubiliser in oral and parenterals formulation and has shown to increase dissolution of poorly soluble drugs. Povidone solutions can also be used as coating agents.

Povidone is used as a suspending, stabilizing, or viscosity-increasing agent in a variety of topical and oral suspensions and solutions.

Uses of Povidone.


Concentration in (%)

Carrier for drugs


Dispersing agent

Up to 5

Eye drops


Suspending agent

Up to 5

Tablet binder, tablet diluents, or coating agent



Povidone is a fine, white to creamy-white color, odorless and hygroscopic powder. Povidone with K-values equal to or lower than 30 are manufactured as spray-drying and occur as spheres. Povidone are manufactured by drum drying and occur as plates.

Melting point:

 Softens at 150°C.

Particle size distribution:

Kollidon 25/30: 90% >50 Î¼m, 50% >100 Î¼m, 5% >200 Î¼m.

Kollidon 90: 90% >200 Î¼m, 95% >250 Î¼m.


Freely soluble in acids, chloroform and ethanol (95%), ketones, methanol, and water; partially insoluble in ether, hydrocarbons, and mineral oil. In water, the concentration of solution is limited by viscosity of the result solution, that is a function of the K-value.

Dynamic viscosity of 5% w/v povidone (Kollidon) solutions in ethanol (95%) and propan-2-ol at 25°C.


Dynamic viscosity (mPa s)

Ethanol (95%)

















Stability and Storage

Povidone darkens by heating at 150°C, with a reduction in aqueous solubility. It is stable in short period of heat exposure around 110-130°C; steam sterilization of aqueous solution cannot change its properties. Aqueous solutions are susceptible to mold growth and require addition of preservatives.

Povidone stored under normal conditions without undergoing decomposition or degradation. The powder is hygroscopic; so, it should be stored in airtight container in a cool, dry place.


Povidone is compatible in solutions with a high range of inorganic salts, natural and synthetic resins.

Sodium alginate:-

Sodium alginate is a sodium salt of alginic acid. Its empirical formula - NaC6H7O6. Sodium alginate is a gum, which is extracted from the cell walls of the brown algae


It is a flavorless gum; it is used by the food industry to increase viscosity and as emulsifier. It is also used as a preparation of dental impressions.

It is a good chelator for removing radioactive toxins from the body, such as iodine-131 and strontium-90. It is used in immobilizing enzymes by inclusion.

Used as a food additive, sodium alginate used in the production of gel-like foods. It is also used in the biological experiments for the immobilization of cells to gain important products like alcohols, organic acids.