Monophasic & Biphasic Liquids

UNIT-3 

Monophasic & Biphasic Liquids

Monophasic Liquids 

• The compounding of solution retains an important place in therapeutics owing to the simplicity of preparation and rapid absorption of soluble medicinal products. Solutions are of particular value for pediatrics, geriatrics and psychiatric patients who have difficulty in swallowing solid dosage forms and in cases where individualized dosages are required. Dosage forms meant either for internal, external or parenteral use may be sub-classified into monophasic or biphasic liquid dosage forms. The monophasic liquid dosage forms consist of either true or colloidal solutions or solubilized system. All these consist of only a single phase and may have either aqueous or non-aqueous solvents as the base.

Gargles  

• Gargles are aqueous solution used to prevent or treat infection. They are usually available in concentrated form with direction for dilution with warm water for use. They are brought into intimate contact with mucous membrane of throat and allowed to remain in contact with it for few seconds, before they are thrown out of mouth.

Storage: Gargles should be dispensed in clear, fluted glass bottles. Colored bottles are required to be used if gargles need protection from sunlight.

Formula: Phenol gargle 

Rx Phenol glycerin - 5 ml 

Amaranth solution - 1 ml 

Purified water - q.s. to 100 ml

Uses: Antibacterial effect, astringent effect, mild anesthetic effect.

Packaging: Pack in flip flop bottles, waterproof packing.

Mouth Wash 

• These are aqueous solutions with a pleasant taste to clean, deodorize the buccal cavity. Mouthwashes have refreshing, antiseptic and antibacterial activity and prevent Halitosis.
• They may also contain alcohol, glycerin, synthetic sweeteners, surfactants, flavouring and colouring agents. They may be either acidic or basic in their reaction and in some instances are fairly effective in reducing bacterial concentration and odours in the mouth for short periods of time.

For example: Compound sodium chloride mouth wash, Zinc chloride mouth wash, Fluoride mouth wash.

Storage: Keep in cool and dry place, Dispense in clear, fluted bottles.

Labeling: FOR EXTERNAL USE ONLY 

1. Not to be swallowed in large amount 
2. Pack in narrow mouth bottle

Formula: Rx 

Zinc sulphate and zinc chloride mouth wash B.P.C. 

Zinc sulphate - 20 g 

Zinc chloride - 10 g 

Oilute hydrochloride acid - 10 ml 

Compound tartrazine solution - 10 ml 

Chloroform water to produce - 1000 ml

• The preparation may be made by dissolving Zinc sulphate and Zinc chloride in small quantity of Chloroform solution. To this is added dilute hydrochloric acid and compound tartrazine solution and the final volume is made up with water.

Throat Paint 

Solution or dispersion of one or more active agents.

• Throat paints are viscous liquid preparations used for mouth and throat infections
• Glycerin is commonly used as a base because being viscous it adheres to mucous

membrane for a long period

• Glycerin prolongs the action of medicaments. 
• Glycerin also provides sweet taste to preparation

Storage: Throat paint should be stored in airtight container and in cool place

Labeling: For EXTERNAL USE ONLY.

Formula: RX 

Potassium iodide - 2.5 gm lodine - 1.25 gm

Alcohol - 4 ml Water - 2.5 ml

Peppermint oil - 0.4 ml

Glycerin - 100 ml

Packing: A wide mouth, fluted, light resistant, screw car glass bottle is used and dispensed in amber coloured bottle. 

Ear Drops 

• Ear drops are liquid preparations meant for instillation into the ear. In these preparations, the drug is usually dissolved or suspended in a suitable solvent such as propylene glycol, polyethylene glycol, glycerol alcohol and water or a mixture of these. Aqueous vehicle is generally not preferred because the secretions in the ear are fatty in nature and as such these do not easily mix with water.

Example: Chloramphenicol Ear Drops

Chloramphenicol - 59 

Propylene glycol q.s to 100 ml

• Chloramphenicol ear drops may be prepared by dissolving Chloramphenicol in sufficient quantity of Propylene glycol and finally making up the final volume with it. 

Nasal Drops 

• Nasal drops are liquid preparations intended for instillation into the nostrils usually with the help of a dropper. Nasal drops are mostly based on aqueous vehicles although oily drops (containing liquid paraffin of suitable viscosity) are not uncommon.

• Commercial nasal preparations usually contain decongestants, antibiotics, antihistamines and drugs for asthma prophylaxis. Examples include Ephedrine Nasal drops, Phenylephrine Nasal drops, etc.

        Nasal drops are usually supplied in amber coloured fluted bottles with rubber teat and dropper                closure.

Example: Ephedrine Nasal Drops

• The drops may be prepared by first dissolving Chloroxuron in small quantity of hot water followed by cooling the solution to room temperature. Other ingredients are then dissolved in the solution, which is filtered, and the final volume is made up with water. 

Nasal sprays 

• Nasal sprays are suspensions or solution of drugs intended for spraying into the nostrils. The chief uses of nasal sprays are to relieve nasal congestion and inflammation and to treat infections. They are intended to be retained in the nasal tract, they are usually viscous and coarse since fine droplets tend to penetrate further into the respiratory tract. 

Enemas 

• Enemas are liquid preparations meant to be introduced into the rectum for cleansing, therapeutic or diagnostic purposes. Evacuation enemas are rectal injections employed to evacuate the bowel in constipation or before an operation. e.g., Enema of soap, Sodium phosphate enema, Olive and arachis oil enema, etc. Retention enemas are usually employed to influence the general system by absorption or to affect locally the seat of disease.

• Large volume enemas are administered from a douche can and should be warmed to body temperature before use. Small volume enemas are available in polythene or polyvinyl chloride bags sealed to a rectal nozzle and these are more convenient for personal administration since the patient has simply to insert the nozzle and squeeze the bag. 

Syrups 

Syrups are sweet viscous concentrated aqueous solution of sucrose in purified water.

Simple syrup I.P contains 66.7%w/w sucrose in purified water (100 ml) 

Simple syrup USP contains 85%w/v sucrose in purified water (100 m.)

Medicated Syrup: Contains a therapeutic or medicinal agent e.g., Cough syrup

Flavored Syrup: Contains flavouring agent but no medicinal substances e.g., Cherr yrup.

Advantages: 

1. Syrup retards oxidation because it is partly hydrolyzed into its reducing sugar such as laevulose and dextrose
2.  They are palatable due to the sweetness of sugar. It is a valuable vehicle for the administration of nauseous and bitter substances.
3. Syrups are good demulcents and soothing agents and hence they are of special value in cough syrup.
4.  Syrups have good patient compliance. 

Concentration of sucrose in sugar-based syrup is very important. A dilute solution may lead growth of micro-organisms whereas aturated solution may lead to cryst zation of same part of sucrose. Both syrup concentrations as per IP and USP gives stable syrup. Syrup containing various concentrations of sucrose needs antimicrobial preservative.

        Method of Preparation: The choice of particular method depends on the physical and chemical             characteristics of the substance being used.

Elixir 

Elixirs are defined as clear, aromatic, sweetened, hydroalcoholic liquids intended for oral us:

• They provide a palatable means of administering potent or nauseous drugs.

• Elixirs are less sweet and less viscous then syrup may contain less or no sucrose.

• Elixirs are more stable than syrups and hence preferred over syrup.

• Elixirs contain 4-40% of alcohol (ethanol).

Types

       Non-medicated: Not contain medicament and used as flavoring agent. 

       For example: Aromatic elixir.

       Medicated: Which contain a potent drug such as antibiotics, antihistamines, sedatives

Biphasic Liquids 

Emulsion 

• An emulsion is liquid preparation containing two immiscible liquids, one of which is dispersed as globules (dispersed phase = internal phase) in the other liquid (continuous phase = external phase)

• Droplets ranging in diameter (0.1-100 um).

• Emulsion is thermo dynamically unstable and is stabilized by presence of emulsifying agent (emulgent or emulsifier)

• Emulsion no more official in L.P.

Types of Emulsion 

Primary emulsion containing one internal phase, for example

• oil-in-water emulsion (o/w) 
• water-in-oil emulsion (w/o).

Secondary emulsion also called multiple emulsion contains two internal phases, for instance,

• o/w/o 
• w/o/w.

It can be used to delay release or to increase the stability of the active compounds.

Test for Emulsion 

Dilution test: Addition of water to a w/o emulsion and oil to o/w emulsion would crack the emulsion and lead to separation of the phases.

Conductivity test: When current is passed to an emulsion which is connected to a voltage bulb, the bulbs glows if it is o/w emulsion since water is good conductor of electricity and when the bulb does not glow it is w/o emulsion because oil is non-conductor of electricity. 

Dye test: Water-soluble dye will dissolve in the aqueous phase whereas oil-soluble dye will dissolve in the oil phase. For example: Amaranth (0/w Emulsion), Scarlet/Sudan (w/o Emulsion).

Theories of Emulsification

• In case of two immiscible liquids, cohesive force between the molecules of each separate liquid exceeds adhesive force between two liquids. This is manifested as interfacial energy or tension at boundary between the liquids.  

Hydrophillic colloids: Forming a multimolecular film around the dispersed droplet. e.g., Acacia.

Finely divided solids: They are adsorbed at the interface between two immiscible liquid phases to form particulate films. e.g., Bentonite and veegum. 

• For large sCale production mechanical stirrers are used to provide controlled agitation and shearing stress to produce stable emulsions.

Dry Gum Method

• In this method, the oil is first triturated with gum with a little amount of water to form the primary emulsion. The trituration is continued till a characteristic ’Clic king' sound is heard and a thick white cream m is formed. Once the primary emulsion is formed, the remaining quantity of water is slowly added to form the final emulsion.

Wet Gum Method

• As the name implies, in this method first gum and water are triturated together to form a mucilage. The required quantity of oil is then added gradually in small proportions with thorough trituration to form the primary emulsion.

Preparation of Emulsions 

• Preparations n of emulsions depends on the scale at which it is produced.

•  On small scale mortar and pestle can be used but its deficiency is limited. To overcome this drawback small electric mixers can be used although care must be exercised to avoid excessive entrapment of air.

Suspensions 

•   Suspensions are biphasic, heterogeneous system in which finely divided insoluble solid particles (disperse phase) are dispersed or suspended in a vehicle (dispersion medium).    

•  The diameter of disperse phase may range from 0.S km to 100 km.     

• Systems in which particle size is below than this ranpe are called colloidal (1 nm - 0.5 km diameter).

                           

Evaluation of Suspension

     (1)     Sedimentation method

(2)     Rheological method

(3)     Electrokinetic method

                    (5)    Micromeritic method