General Excipients used in Monophasic liquid preparation

Excipients used in Monophasic Pharmaceutical liquid preparation as below

1.      Vehicle:

·         Purified water

·         Aromatic water: chloroform, peppermint, cinnamon, dill water

·         Syrups

·         Glycerin (glycerites)

·         Elixirs (hydro alcoholic)

2.      Solvents used in internal solution:

Solvent	Properties	Remarks/Use
Aqueous liquids
Water	Cheap, Good solvent action, High dielectric constant, Miscible, Non-Inflammable, Inert	Sugar, gum, organic acid, tannins, glycosides, alkaloid salt are soluble easily, Cellulose, starch resin, fixed oil, volatile oils are insoluble
Purified water (Distilled water)	Prepared by distillation or ion exchange method	Used for other than parenteral product
Water for Injection (WFI)	Sterile, Pyrogen free distilled water	For parenteral use
Sterile water	WFI sterilized and suitably packed	For parenteral use
Bacteriostatic WFI	WFI sterilized and containing one or more suitable antimicrobial	For parenteral use
Oily liquids
Corn oil (vegetable)	Clear, light yellow	Solvent and vehicle for Injection
Cotton seed oil (vegetable)	Pale yellow, Odorous	Solvent and vehicle for Injection
Peanut Oil (vegetable)	Colorless to pale yellow	Solvent and vehicle for Injection, uesd in liniment
Sesame oil (vegetable)	Pale yellow, odorless	Solvent for Injection, used in cosmetic, liniment & ointment
Ethyl oleate (synthetic)	Pale yellow, Disagreeable odour and taste, low viscosity	Vehicle for IM injection
Silicons	Low M.W- liquid form, High M.W.–semi-solid form	Used in dermatological preparation.
Hydroxylated Compounds
Ethanol	Miscible with water, Antimicrobial property	Costly due to high excise duty
Propylene glycol	As a solvent, preservatives, Replace alcohol & glycerin, Miscible with water, Solvent for vitamins, steroids, barbiturates etc	For oral preparation, For hydrophilic ointment, Used in injection of barbiturates digitoxin, iodine
Glycerol	Colorless, sweet taste, hygroscopic, as a solvent	Use as solvent, preservatives, humectant, in throat paints, linctus, syrup, elixirs
1,3 butylene glycol	Colorless, viscous, miscible with water	Used as solvent for morphine injection
Poly ethylene glycol	PEG-300 & 400 are liquid, colorless	Used in lotion, used as solvent in parenteral preparation.
Sorbitol	White, Hygroscopic, sweet taste	70% w/w used as vehicle

·         Aqueous solvents: Water, Purified water, water for injection, sterile water & bacteriostatic water for injection

·         Oils and oily materials:

o   Animal Source: lard

o   Vegetable sources: corn, cotton, castor oils

o   Mineral sources: liquid paraffin

o   Synthetics: ethyl oleate, silicons

·         But, Oils have following problems

o   Rancidity on keeping & Allergic reaction

·         Hydroxylated compounds: Ethanol, propylene glycol, glycerol, sorbitol, PEG

·         Modern vehicle: Glycofurol, dimethylacetamide

3.      ORGANOLEPTIC ADDITIVES:

a.      Flavours (Flavouring agent):

Choice of flavour according to the taste
Taste	Flavours
Alkaline	Mint, Chocolate, Vanilla
Sour (Acidic)	Lemon, Orange, Raspberry, Strawberry
Bitter	Mint, Fennel, Chocolate, Cherry
Metallic	Grape, Lemon, burgundy
Salty	Citrus, Raspberry, Fruit, apple
Sweet	Vanilla, Honey
Choice of flavour according to colors
Colors	Flavours
Pink to Red	Cherry, Raspberry, Strawberry, Apple, Rose
Brown	Chocolate, Honey, Caramel, Walnut
Yellow to Orange	Lemon, Lime, Orange, Cherry
Green	Banana, Mint
White to off white	Vanilla, Banana, Jasmine, Mint, Spearmint
Violate to Purple	Grape, Liquorice
Blue	Mixed fruit, Pulm, Blueberry, Liquorice

b.      Colour (Colouring Agent):

·         A substance that gives color to pharmaceutical preparations are called coloring agents.

·         The function of these ingredients is to enhance the product quality. They provide-

o   Product identification.

o   Protect the core from light and moisture.

o   Enhance the appearance of a preparation, Consistent appearance to formulation

o   The acceptability of a preparation by the patient.

·         Colours are often matched to the flavour of a preparation, e.g. a yellow colour for a banana-flavoured preparation.

Ideal properties of colours:

o   Non-toxic & No any therapeutic activity.

§  Natural colours are most likely to meet this criteria, e.g. carotenoids, chlorophylls, saffron, red beetroot extract, caramel and cochineal.

o   Good Photo stability of the colour

·         Approved status of colour/dye from governing body.

Classification of colours:

·         Natural colours: obtain from plant, mineral and animal source

o   Plant Source: chlorophyll-green, carots-yellow, indigo-blue, saffron-yellow, caramel-Brown (Burnt sugar)

o   Mineral Source: Red & yellow ferric oxide, titanium dioxide, carbon black, lead chromate, Prussian blue

o   Animal Source: Cochineal, Carmine

o   Colours of substance:

§  White: Titanium dioxide,

§  Blue : Brilliant blue ,Indigo carmine,

§  Red : Amaranth Carmine,

§  Yellow: saffron, Green, carots

§  Brown: caramel

·         Synthetic colours:

o   Mauveine (perkin’s purple)

o   The coal-tar dyes

o   Synthetic dyes are toxic, so their use is regulated by drug and cosmetic Act (D & C act)

o   According act certified colour classified as following:

Group I	FD & C Colour	Used in food, drug and cosmetic
Group II	D & C colour	Used in drug and cosmetic
Group III	Externally D & C	Used in externally applied drug and cosmetics.
Example of permitted synthetic colour
Blue	Briliient blue, Indigo Carmine
Green	Gast green, Guinea green
Violet	Wood violet
Red	Amaranth (Water soluble), erythrosine, Scarlet red (oilsoluble)
Yellow	Tartrazine, Sunset yellow

c.       Taste (sweetening agent):

·         For better palatability of the dosage form

·         Examples: sucrose, sorbitol, glycerin, honey, saccharin sodium, aspartame.

·         Sucrose: generally used sweetening agents

·         Sorbitol: it is half sweet as sucrose.

o   Widely used in lozenges due to its pleasant cooling sensation,

o   In large dosage act as laxative.

o   Have hygroscopic nature so, used as humectant in cosmetic and lotion.

·         Glycerin: used as solvent and preservatives. Act as humectant.

·         Honey:

·         Cyclamate sodium: 30-40 times sweeter than sucrose.

·         Saccharine sodium: 300-550 time sweeter than sucrose.

·         Aspartame: 250-300 time sweeter than sucrose

Reference: Pharmaceutics-2, by Dr. G.K.Jani