LIQUID DOSAGE FORMS - Centurion University
Transcript of LIQUID DOSAGE FORMS - Centurion University
LIQUID DOSAGE FORMS
By
C.Nivetha
IV Pharm. D
INTRODUCTION:
• A liquid dosage form is the liquid form of a dose
of a chemical compound used as a drug or
medication intended for administration or
consumption.
• Monophasic liquid dosage forms are
represented by true or colloidal solution.
• The component of the solution which is
present in a large quantity is know as
“SOLVENT” where as the component present
in small quantity is termed as “SOLUTE”.
Classification:
Monophasic liquid dosage form:
A.INTERNAL:
1. Mixture
2. Syrup
3. Elixir
4. Linctus
B. EXTERNAL:
1. Application on the skin: liniment, lotion
2. Used in the mouth: gargles , mouth wash , throat paint
3. Instilled into body cavities : douche , ear drop , nasal drop, nasal spray
Liquids meant for internal
administration: MIXTURES:
A mixture is a liquid preparation meant for oral administration in which medicament or medicaments are dissolved or suspended in a suitable vehicle
Mixtures are not prepared to keep them for a long period because they are mainly prescribed for acute condition such as cough, indigestion ,diarrhoea,constipation.
Classification:
Simple mixtures containing soluble
substances.
Mixtures containing diffusible solids.
Mixtures containing indiffusible solids.
Mixtures containing precipitates forming
liquids.
Mixtures containing slightly soluble
liquids.
Formulation of mixtures:
1.Vehicles:The vehicle commonly used for
the preparation of mixtures are:
(a) Water : Purified water should be used
for the preparation of mixtures.
(b) Aromatic water : These are saturated
solution of volatile oil and volatile
substance in purified water. Aromatic
water is mainly used for its flavouring
properties.
cont….
2.Adjuncts:
a) Chemical stabilizers : Certain chemicals
having antioxidants or reducing
properties are used to improve the
chemical stability of the mixtures.
Eg . ascorbic acid, sodium metabisulphite
b) Colouring agents: No special colouring
agents are added but many mixture
contain coloured medication
cont….
(c) Flavouring agents: The following flavouring agents are added commonly used in mixtures:
Aromatic water such as anise water.
Syrup and glycerol for sweetening children preparation
Liquid extract of liquorice to mask the saline taste.
Spirit lemon to cover the taste of alkaline citrates
cont….
(d) Preservative: Diluted vegetables extract
and flavouring agents are the source of
growth of micro organism. Hence
chloroform(0.25%) and benzoic
acid(0.1%) is used to preserve such
mixture.
SYRUPS: A syrup is a concentrated solution of sucrose in
purified water.
The concentration of sugar is 66.7% w/w.
Formulation of syrup:
Vehicle: purified water
Chemical stabilizers : glycerin , sorbitol , propylene glycol
Colouring agents : coal tar dyes such as amaranth is used.
Flavouring agents : tinctures lemon , fruit juices , essence.
Preservatives: the syrup containing 66.7% w/w of sucrose have high osmotic pressure which prevents growth of microorganism. So no preservative is needed.
Preparation of syrup:
water + sucrose(heating)
stir well
filter
allow it to cool
cont….
API + add q.s.water to solubilize
other agents
then mix with simple syrup
Sucrose should not dissolved in high temperature because the sucrose gets hydrolysed, results in the formation of dextrose and fructose, these two sugars together called as invert sugar and the process is known as inversion. This reaction takes place more rapidly in presence of acids. The inversion leads to darkening of the solution.
SOLUTION
Solutions are clear Liquid preparations
containing one or more active ingredients
dissolved in a suitable vehicle.
CLASSIFICATION OF SOLUTION:
a) Oral solutions—through oral route.
b) Otic solutions—instilled in the ears.
c) Ophthalmic solution—instilled in the eyes.
d) Topical solutions—applied over the skin
surface.
METHODS OF PREPARATION
Methods of Preparation of Solutions
(a) Simple Solution
(b) Solution by Chemical Reaction
(c) Solution by Extraction
Simple solution:
Simple Solution Solutions of this type are
prepared by dissolving the solute in a
suitable solvent (by stirring or heating ).
The solvent may contain other
ingredients which stabilize or solubilize
the active ingredient .
E.g. solubility of iodine is more in KI when
compared with water because the
formation of soluble polyiodides
Solution by chemical reaction:
These solutions are prepared by reacting two or more solutes with each other in a suitable solvent e.g. Calcium carbonate and lactic acid used to prepare Calcium lactate mixture.
Solution by Extraction:
• Solution by Extraction Plant or animal products are prepared by suitable extraction process. Preparations of this type may be classified as solutions but more often, are classified as extractives.
BIPHASIC LIQUID DOSAGE
FORM 2 types of biphasic liquid dosage form are:
(i) Suspension
(ii) Emulsion
SUSPENSION
Suspension are the biphasic liquid dosage form of medicaments in which the finely divided solid particles ranging from 0.5 to 5.0 microns are dispersed in a liquid or semisolid vehicle.
The solid particles act as disperse phase whereas liquid vehicle act as the continuous phase
The particle size of the disperse phase is very important in the formulation of suspensions.
Qualities of suspension:
It should settle slowly and should be readily re-dispersed on gentle shaking of the container.
The suspension should pour readily and evenly from its container.
It should be chemically inert.
The suspended particles should not form a cake.
It should be free from large particles which spoil its appearance.
Classification of suspension
Oral suspension
Parenteral suspension
Ophthalmic suspension
Suspension of external use
Flocculated and Non-flocculated
suspension: The suspension are said to be flocculated
, when the individual particles are in
contact with each other and form a
network like structure.
Whereas in case of non-flocculated
suspension , the individual particles exists
as a separate entity.
Components
Function
API Active
drug substances
Wetting
agents
They
are added to disperse solids in continuous liquid phase.
Flocculating
agents
They
are added to floc the drug particles
Thickeners They
are added to increase the viscosity of suspension.
Buffers
and pH adjusting agents
They
are added to stabilize the suspension to a desired pH range.
Osmotic
agents
They
are added to adjust osmotic pressure comparable to biological
fluid.
Coloring
agents
They are added to impart desired color to suspension and
improve elegance.
Preservatives They
are added to prevent microbial growth.
External
liquid vehicle
They are added to construct structure of the final suspension.
Preparation of suspension:
EMULSION
An emulsion is a thermodynamically unstable system consisting of at least two immiscible liquid phases one of which is dispersed (the dispersed phase) as globules in the other liquid phase (the continuous phase) stabilized by a third substance called emulsifying agent.
Particle diameter of dispersed phase (Internal phase) ranged from 0.1 to 10 µm.
TYPES OF EMULSION
Oil-in-water (O/W)
Water-in-oil (W/O)
DIFFERENCE BETWEEN O/W
AND W/O EMULSIONS:
O/W EMOLSION W/O EMULSION
Water is the dispersion medium
and oil is the dispersed phase
Oil is the dispersion medium and
water is the dispersed phase
non greasy and easily removable
from the skin
greasy and not water washable
used externally to provide cooling
effect e.g. vanishing cream
used externally to prevent
evaporation of moisture from the
surface of skin e.g. Cold cream
preferred for internal use as bitter
taste of oils can be masked.
preferred for external use like
creams.
Formulation of emulsion
(A) Emulsifying agent:
The emulsifying agent reduces the
interfacial tension between two phases
i.e.oily phase and aqueous phase and
thus make them miscible with each
other and form stable emulsion.
IDEAL PROPERTIES OF
EMULSIFYING AGENT: It should be capable of reducing the
interfacial tension between the two immiscible liquids
It should be compatible with other ingredients of the preparation
It should be non toxic
It should be capable to produce and maintain the required consistency of the emulsion
It should be chemically stable
Classification of emulsifying agent:
(i)Natural
(a)From plant origin
Polysaccharides ( Acacia, tragacanth, agar, pectin)
(b)From animal origin
Proteins ( Gelatin)
Lecithin
Cholesterol
Wool fat
Egg yolk
(ii)Semi synthetic ( Multi molecular films)
Methyl cellulose
Carboxy methyl cellulose
Preparation of emulsion:
Water in oil type emulsion:
internal phase(water)+emulsifying agent
triturate well
add external phase(oil) in drop wise
(primary emulsion)
Triturate until a homogenous phase is formed
Oil in water type emulsion: visa versa