Semi Solid Preprations

F O R M U L A T I O N D E V E L O P M E N T O F S E M I S O L I D D O S A G E F O R M S

PRESENTED BY:

Thet-ul-wafa Maqsood

Baqai institute of pharmaceutical Sciences

Baqai medical university

SEMISOLID DOSAGE FORMS

Creams

Ointments

Pastes

Gels

The SEMISOLID DOSAGE FORMS includes


Definition:

Semisolid dosage forms are dermatological preparations

intended to apply externally on the skin to produce local or

systemic effect.

Ex: Ointments, creams, pastes, gels etc


IDEAL PROPERTIES OF SEMISOLIDS:

o PHYSICAL PROPERTIES

o APPLICATION PROPERTIES

o PHYSIOLOGICAL PROPERTIES


PHYSICAL PROPERTIES

o Smooth texture

o Non dehydrating

o Non gritty and non greasy

o Elegant in appearance


PHYSIOLOGICAL PROPERTIES

o Non irritating

o Do not alter membrane or skin functioning

o Miscible with skin secretion


APPLICATION PROPERTIES:

o Easily applicable with efficient drug release.

o High aqueous wash ability.


Types of semisolid bases:

The ointment base is the substance or part of ointment, which

serves as carrier or vehicle for the medicament. bases are of

following types.


A) Oleaginous bases or Hydrocarbon base

Ex. Hard paraffin, Yellow soft paraffin.

B) Absorbent base

Ex. Hydrous wool fat, lanolin

C) Emulsion bases or water miscible bases

D) Water soluble bases

Ex. PEG, Polysorbate

PREPARATION OF SEMI SOLIDS

Trituration method

Ex. Ointmentscreamspastes

Fusion method

Chemical reaction method

Emulsification

method

Ex. Ointmentscreamspastes

Ex. Ointments

creams Ex. Ointments

creams



Equipments used are:

o Homogenizer

o Collide Mill

o Filling equipment

o Packaging operation.

HOMOGENIZERS:

For homogenization colloidal mill is

used.

Colloidal mill:

It consists of two steel discs one is

stationary and other is rotating.when

the material is passed through these

discs they get sheared. Thus,coarse

particles are broken down to small

particles due to shear.


Uses:

Used for preparation of

suspensions,ointments.

Advantage :

It can be easily sterilised.

Disadvantage:

Heat is generated during milling.


Fusion method:Anhydrous ointments are prepared by fusion

method.

Active substances is dissolved in the melted fats and waxes and then mixed with base. The melted mass must mixed while cooling because the fatty alcohols, fatty acids, and waxes do not form true solutions, but crystallize from the melt as the temperature falls.


Homogenization frequently increases the consistency of a

semisolid emulsion because it increases the number of emulsified

particles.

consistency is affected by

1. Number of passes through the homogenizer.

2. Pressures used for homogenization.


Aeration should be avoided, since it may lead to emulsion instability

and variation in density.

Aeration maybe prevented at the primary emulsion step if one phase

is introduced into the other in such a manner that splashing and

streaming are avoided.

Splashing can overcome by careful adjustment of the mixing

conditions and liquid flow pattern.

Completely enclosed kettles are available for the manufacturing of

semisolids which tend to aerate excessively.


Manufacture of emulsified semisolids:

Time, temperature and mechanical work are the three variables in the

manufacture of emulsified semisolids. The three factors are interrelated and must

be carefully controlled if the same high quality batches are to manufactured.

Equipment is available for automatically controlling many aspects of

emulsion manufacture, such as the complete control of the temperature in the jacket

and regulation of the mixing time and rate of agitation

PREPARATION OF OIL AND

AQUEOUS PHASES

PREPARATION

(Oil Phase)

The components of the oil mixtures are placed into a stainless steel

steam jacketed kettle, melted and mixed.

Some of the solid components e.g. stearic acid, cetyl alchol are

available in many different forms like cakes, flakes or powder. The

flakes are more preferable because of the convenience of handling.

Petrolatum (a Hydrocarbon base) is inconvenient to handle unless it

is melted and transferred by pumping or pouring from its drum.

The oil phase is then strained through several layers of

cheese cloth to remove any foreign matter.

If petrolatum is used as oil phase then it should be passed

through filter medium particularly in ophthalmic

preparations.

The oil phase is transferred by gravity or pump to the

emulsion mixing kettle.

PREPARATION

(Aquous Phase)

The components of the aqueous phase are dissolved in the

purified water and filtered.

A soluble drug may be added to this aqueous phase.

PREPARATION

MIXINGOF

PHASES

MIXING

The phases are usually mixed at a temperature of 70 to

720C,because at this temperature intimate mixing of the liquid

phases can occur.

The properties of some emulsions depend on the temperature at

which the phases are mixed. The initial mixing temperature must

be raised above 70 to 72 0C.

Equipments used for mixing of phases:

Agitator mixers :

Sigma mixer and planetary mixer.

Shear mixers:

Triple roller mill and Colloidal mill.

MIXING

COOLING

COOLING THE SEMISOLID EMULSION:

The rate of cooling is generally slow to allow for adequate mixing

while the emulsion is still liquid.

The temperature of the cooling medium in the equipment should

be decreased gradually and at a rate consistent with the mixing of

the emulsion and scrapping of the kettle walls to prevent formation

of congealed masses of the ointment or cream.

GELS

Includes in semi solid preparation but It is normally formulated as a suspension.

WHAT IS GEL?

Pharmaceutical gels are semisolid systems in which there is interaction (either

physical or covalent) between colloidal particles within a liquid vehicle.

OR

A 3D matrics system In which the Active Pharmaceutical Ingredient is invaded.

The vehicle may be:

Aqueous

Hydroalcoholic

Alcohol based Or

Non Aqueous

P H A R M A C E U T I C A L C O N S I D E R AT I O N O F

P H A R M A C E U T I C A L G E L S

Includes:

Choice of vehicles

Inclusion of buffers

Preservatives

Antioxidants

Flavoring and coloring agents

GELLING AGENT

These are substances which, when added to an aqueous mixture,

increase its viscosity without substantially modifying its other properties,

such as taste. They provide body, increase stability, and improve

suspension of added ingredient.

Ex. Ethylcellulose , hydroxypropyl cellulose etc.

GELLING AGENT

3 types of Gelling Agents:

1. Natural Polymers

Tragacanth

Geletin

2. Semi synthetic Polymers

Carboxy methylcellulose.

Methylcellulose.

3. Synthetic Polymers

Carbomer.

• Obtained from Collagin (in plants).

• Biocompatable .

• Can be used in parentrales.

• Should be soaked over night.

• Forms clumps in water.

• Glycerin and propylene glycol should be used as a humectant.

1 . NA TURAL P OLYME RS

Tragacanth Geletin

Used in the conc. Of 4-6%

Insoluble in water.

Also use as viscosity Enhancers.

Used in the conc. Of 5%

Ethylene and propylene glycol

should be used as a humectant.

2 . S E MI S YNTHETI C P OLYMERS

Carboxy methylcellulose. Methylcellulose.

3 . S YNTHETI C P OLYMERS

An acrylic based polymer.

Used in the conc. Of 0.5-1%

Also used as thickning and suspending agent.

GELLING AGENT

PREPARATION OF GELS

Water

Preservative

• Gelling agent

SoakeOver night

Add Glycerine

With propylene

glycol mixed with

API

And then make up

the volume

DURATION OF SWELLING

A swelling duration of about 24 – 48 hours generally helps in

obtaining homogeneous gels.

Natural gums need about 24 hours.

cellulose polymers require about 48 hours for complete

hydration.

A person who Never made a mistake never tried any thing new…

“Albert Einstein”

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Health & Medicine

Semi Solid Preprations