DISPERSE SYSTEM PRODUCTION

Seminar on

DISPERSE SYSTEM PRODUCTION

byNayala Firdous

(170713886005)

Under The Guidance Of

DR.MUQTADER

AHMEDM.Pharm,Ph.D

Head Of Department Of

Pharmaceutics

MASTER OF PHARMACY

DEPARTMENT OF PHARMACEUTICSDECCAN SCHOOL

OF PHARMACY Dar-us-salam, Aghapura, Hyderabad-01. A.P. India

1Department of Pharmaceutics

INTRODUCTION

A disperse system is defined as a heterogenous, two phase

system in which the internal (dispersed, discontinuous) phase

is distributed or dispersed within the continuous (external)

phase or vehicle.

Based on the particle size of the dispersed phase,

dispersions are generally classified as

Molecular dispersions

Colloidal dispersions and

Coarse dispersions.


Classification of dispersed system by

particle size


FORMULATION ADDITIVES

Surfactants

Protective Colloids and Viscosity-Imparting Agents

pH-Controlling Agents

Preservatives

Antioxidants


COARSE DISPERSION

Coarse dispersions are heterogeneous dispersed systems, in

which the dispersed phase particles are larger than 1000 nm.

Coarse dispersions are characterized by relatively fast

sedimentation of the dispersed phase caused by gravity or

other forces. Dispersed phase of coarse dispersions may be

easily separated from the continuous phase by filtration.

Includes:

a. Suspensions and

b. Emulsions


SUSPENSION

Typically, the suspensions with particle size greater than ~1

µm are classified as coarse suspension, while those below 1

µm are classified as colloidal suspension. When the particles

constituting the internal phase of the suspension are

therapeutically active, the suspension is known as

pharmaceutical suspension.

Ideally, the internal phase should be dispersed uniformly

within the dispersion medium and should not sediment during

storage.


Sedimentation and Stokes’ Law

A flocculated suspension sediments faster and is

easy to redisperse, whereas a deflocculated

suspension sediments slowly and is difficult to

redisperse. The rate of sedimentation of particles

can be determined by Stokes’ law:


Important Considerations in Formulation

of Suspension

Nature of suspended material

Size of suspended particles

a) Micropulverization

b) Fluid energy grinding

Viscosity of the dispersion

medium


EMULSION

An emulsion is a dispersion of at least

two immiscible liquids, one of which is

dispersed as droplets in the other

liquid, and stabilized by an emulsifying

agent. Two basic types of emulsions

are the oil-in-water (O/W) and water-in-

oil (W/O) emulsion. Depending upon

the need, more complex systems

referred to as “double emulsions” or

“multiple emulsions” can be made,

water-in-oil-in-water (W1/O/W2) or oil-in-

water-in-oil (O1/W/O2).


Mechanism of Emulsification

When two immiscible liquids are in contact with each other,

the molecules at the interface experience an imbalance of

perpendicular forces. The interfacial tension tend to minimize

the surface area of individual liquids.

The process of dispersion of one liquid in the other results in

an increase in surface area between the dispersed droplets

and dispersion medium, and surface free energy, which can

be expressed as follows:

∆W = γ∆ A


HLB ranges of surfactants

The amphiphilc nature of surfactants can be expressed in

terms of an empirical scale of so-called hydrophile–lipophile

balance (HLB) system, established by Griffin. The HLB

system provides a scale of hydrophilicity (0–20) and the

relationship between HLB values and the expected activity

from surfactants isHLB range Application

1–3 Antifoaming

3–6 W/O emulsifier

7–9 Wetting agent

8–18 O/W emulsifier

13–15 Detergent

15–18 Solubilizer


COLLOIDS AND COLLIODAL DISPERSION

A colloid is defined as a system consisting of discrete particles in

the size range of 1 nm to 1 mm, distributed within a continuous

phase.

Molecules of a hydrophilic colloid have an affinity for water

molecules and when dispersed in water become hydrated.

Hydrated colloids swell and increase the viscosity of the system,

thereby improving stability by reducing the interaction between

particles and their tendency to settle.

A hydrophobic colloid has little or no affinity for water

molecules in solution and produces no change in system

viscosity. 12Department of Pharmaceutics

GELS AND MAGMAS

Gels in which the

macromolecules are

distributed so that no

apparent boundaries exist

between them and the

liquid are called single-

phase gels.

When the gel mass

consists of floccules of

small, distinct particles, the

gel is classified as a two-

phase system and

frequently called

a magma or a milk.


PARENTERAL DISPERSE SYSTEMS

Parenteral Emulsions Parenteral Suspensions

In addition to the general

requirements for parenteral

products (e.g., sterility,

nontoxicity, and stability),

particular attention must be paid

to the droplet size and surface

charge of parenteral emulsions,

since these parameters can

directly affect both toxicity and

stability.

Parenteral suspensions

consist of a solid phase, which

is dispersed within a liquid

phase.

Because of particle sizes in

the micrometer range,

parenteral suspensions are

generally limited to either

subcutaneous or

intramuscular routes of

administration.


EQUIPMENTS

PROPELLER MIXERS ROTOR/STATOR MIXER


STATIC MIXER

A static mixer is a precision engineered device for the continuous

mixing of fluid materials.

The energy needed for mixing comes from a loss in pressure as

fluids flow through the static mixer.

The typically helical elements can simultaneously produce patterns

of flow division and radial mixing.


http://en.wikipedia.org/wiki/Helical

MICROFLUIDIZER TECHNOLOGY

The interaction

chamber consist of

microchannels as

narrow as 50 microns

and cause the flow of

product to occur as

very thin sheets.

Used to prepare

unilamellar liposomes

and micro emulsions.


HIGH PRESSURE HOMOGENIZER

The use of high pressure

homogenizers is

recommended when a

disintegration down to the

nano range is required.

The pressure build-up within

the HPH occurs by means of

piston pump ensure(s) a

volume flow that is

independent of pressure and

virtually pulsation free. 18Department of Pharmaceutics

THREE ROLL MILLS

A three roll mill is a

machine that uses shear

force created by three

horizontally positioned rolls

rotating in opposite

directions and different

speeds relative to each

other, in order to mix,

refine, disperse, or

homogenize viscous

materials fed into it. 19Department of Pharmaceutics

COLLOID MILL

Colloid Mill is an ideal

and perfect

homogenizer-cum-

emulsifier. It finds its

application in various

processes like

grinding,

homogenizing,

emulsifying,

dispersing, mixin,

extracting etc.20Department of Pharmaceutics

SUSPENSIONS STABILITY

PHYSICAL STABILITY CHEMICAL STABILITY

Particle-particle interaction

and its behaviour

Interfacial properties of solids

Poly-dispersity: (variation in

particle size)

Most of the drug materials

although insoluble, when

suspended in a liquid medium

has some intrinsic solubility,

which triggers the chemical

reactions such as hydrolysis,

to occur leading to

degradation.


EMULSIONS STABILITY

PHYSICAL INSTABILITY CHEMICAL INSTABILITY

Creaming (sedimentation)

and its avoidance.

Flocculation prevention.

Coalescence (breaking,

cracking)

Oxidation

The rancidity is manifested by

the formation of degradation

products of unpleasant odour

and taste. These problems

can occur with certain

emulsifying agents, such as

wool fat or wool alcohols.


REFERENCE

• Modern pharmaceutics, Forth edition Revised and expanded edited by Gilbert S. Banker University of Iowa Iowa City, Iowa Christopher T. Rhodes University of Rhode Island Kingston, Rhode Island, Marcel Dekker, New York.

• Alok K Kulshreshtha, Onkar N. Singh, G. Micheal Wall Pharmaceutical Suspension from formulation development to manufacturing, Springer

• Pharmaceuticals dosage forms: disperse systems volume 2,3; Herbert A. Lieberman, Martin M. Rieger and Gilbert S. Banker, informa health care.

• Ansel's Pharmaceutical Dosage Forms and Drug Delivery Systems ninth edition, Loyd V. Allen, Jr. Nicholas G. Popovich, Howard C. Ansel,

• Modern Pharmaceutics Volume 1 Basic Principles and Systems edited by Alexander T. Florence JuergenSiepmann, informa health care.



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DISPERSE SYSTEM PRODUCTION