B.Pharmacy 1st year pharmaceuitcs-1 Notes
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| What is biphasic liquid dosage form? |
Biphasic liquid dosage form is consist of two phases i.e suspension and emulsion.
●Undissolved phase is distributed throughout a vehicle and intended for oral administration.
●In this preparation this phase is called dispersed phase and the vehicle is known as 'Dispersed Medium'
●It is also called as internal and external phase respectively.
●The need of biphasic liquid dosage form arise when medicaments are poorly soluble in solvent medium.
●Medicaments from dispersed phase of system which might be either solid or liquid.
Definition of Suspension and Emulsion:
●When Solid Medicament is distribute in dispersion, the system formed is called SUSPENSION.
●When Liquid Medicament is distribute in dispersion, the system formed is called EMULSION.
Suspending agent & emulsifying.agent:-
The Suspension and emulsion are two highly unstable systems are made stable by adding two agents i.e Suspending agent and emulsifying agent.
Biphasic liquid dosage form is consist of two phases i.e suspension and emulsion.
1) Emulsions:
Emulsions are a thermodynamically unstable heterogeneous biphasic system that combines two immutable liquids, one of which is dispersed as minute molecules to another.
This type of formulation is stabilized using an emulsifying agent. Internal phase droplets usually vary in diameter from 0.1 µm to 100 µm.
Biphasic liquid compound containing two non-miscible liquids, one of which is dispersed minute droplet (globule) in to the other.
Dispersed phase:-The liquid which is converted in to minute droplets (globules) is called the dispersed phase
Continuous phase:-The liquid in which the droplets (globules) are dispersed is called the continuous phase.
When emulsifying agent is added to the system then two immiscible liquids can be dispersed for a long period.
Stable emulsion is formed when it forms the film around the globules in order to seprate them frequently in the continuous phase.
Classifications of Emulsion:-
Emulsions are mostly classified as oil in water (o/w) emulsions and water in oil (w/o) emulsions.
1) Oil in water type (O/W): Emulsion in which oil is I dispersed phase whereas water is in continuous phase.
The O/W type phase or emulsions are preferred for interior use.
In these emulsions gum acacia (gum wood), tragacanth (stabilizer), methyl cellulose, glucoside (saponins) synthetic material and soaps formed from monovalent bases like sodium (Na), potassium (k) are used as an emulsifying agent.
2) Water in oil type (W/O): Emulsion in which water is in the dispersed phase whereas oil is in continuous phase.
Calcium, magnesium and zinc are divalent bases used as emulsifying agent forms wool wax, resins, beeswax and soaps.
The W/O emulsions are used externally as creams or lotions.
3) Intravenous emulsion: The oil soluble hormones like vitamin A,D and K are injected as intravenous injection.
The emulsified oils are also injected as diagnostic aids.
The emulsion should have small globule dimension and must be sterile.
4) Emulsion for external use: The emulsions for external administration may be both O/W or W/O type but O/W type emulsion is preferred.
When a medicine is emulsified its rate of penetration through the skin may get reduced.
It helps to prolong the action of a medicine.
Generally the emulsions for application to the skin are semisolid at room temperature and are considered as excellent vehicle.
Uses of emulsions:-
Emulsions are used for
1)Intravenous administration,
2)For external use, Eg: Emulsions for topical administration.
3)Oral administration
Eg: Liquid Paraffin Emulsion IP
2) Suspensions:
Suspensions are heterogeneous biphasic and thermodynamically unstable liquid dosage form of medicaments in which insoluble solid particles (as internal, discontinuous or dispersed phase) is uniformly dispensed in liquid phase (continuous, dispersion, or external phase).
In suspensions finely split particles ranging from 0.5 to 5 microns are dispersed in a liquid vehicle.
Uses of suspensions:-
1)Suspensions are used for external, parenteral and oral applications.
2)Suspensions which are used for external applications should have small particle diameter to avoid gritty feeling to the skin and to cover a larger area of the skin.
3)Smaller particles also helps in perforation of medicine through the skin.
Questions and answers:-
1)What is biphasic suspension?
A suspension is biphasic system in which dispersed phase is solid while continuous phase is liquid aqueous or oily the mechanism is stabilized by addition of suspending agents.
2)What is monophasic suspension?
Monophasic suspension is a liquid preparation containing two or more components in one phase system.
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