INTRODUCTION

TO PELLETIZATION

PELLETS Geometrically defined agglomerates of size range 0.5 -0.15

mm.

REASONS FOR PREFERANCE

Flexibility is dosage form design and development Increace sefty and efficacy Design as CDDS Less susciptible to dose dumping and than reservoir type CDDS When formulated as CDDS

Allows combined delivery of two or more bioactive agents(may not compatible with each other)

Release of drug at a single point or different point of GIT Allows combination of pellets having different release in a single dose Ideal of shape for applying film coating(as low surface area to volume ratio)

Free flowing Elimination of dust Improved hardhess and friability

CLASSIFICATION OF PELLETIZATION PROSSES

SPHERONIZATION

Definition of Spheronization: The formation of small spheres of material.

Spheronization, or Maramuerization, is a rapid and flexible process where pharmaceutical products are made into small spheres, or spheroids.

Spheronized products are relatively dense, of a uniform in size and shape and have defined surface characteristics.

INTRODUCTION

Friction plate Vertical Hollow cylinder or bowl Powder Feeder Temperature controlling jacket Plate cleaning device Baffles Discharge chute

BASIC SPHERONIZER COMPONENTS

Two types Cross hatch pattern

Grooves intersect each other at 90° angle Radial design plate

Grooves emerges from centre like spokes of a bycicle More cutting edge is perpendicular to the direction of

rotation increasing energy transfer As grooves outward from centre so distance between

cutting edge decreases which decreases effectiveness

Greed pattern Matched with desired particle size Groove opening should be 50 to 100% larger than particle size

required Plate design use a ring of teflon or similar material at outer

circumstance to……… Prevent material build up at edge Increase up word motion of particles

DESIGN OF FRICTION PLATE

POWDER FEEDER-To decrease moisture content and to decrease agglomeration Powder coat outside the particle and absorbs moisture that may migrate

to surface during spheronization The powder should be a component of formulation JACKET-Jacket increase temp of inside wall and drive off moisture prevent accumulation of moisture or organic solvent which

lead to collection of product on the wall For temperature sensitive products cooling of wall protect

the product from heat generated by the process Used to control viscosity, plasticity and sticking tendency

PLATE CLEANING DEVICE A brush at the end of hydraulic cylinder that extend

downward and contact with plate periodically BAFFLES Contain several arms with pitched blade rotate in the same

axis but opposite direction to that of friction plate Placed close to friction plate and cylinder wall It increases agitation wiping the inside wall so direct the

product to better contact with friction plate

Extrudates(cylindrical segments) are charged into the spheronizer

Friction disk spins at high speed at the bottom of the cylindrical bowl

Cylindrical extrudate segments are cut into segments with a length ranging from 1 to 1.2 times the diameter

These segments then collide with the bowl wall and they are thrown back to the inside of the friction plate.

Centrifugal force sends the material to the outside of the disc

These cylindrical segments are gradually rounded by the collisions with the bowl wall, the plate and each other.

PROCESS OF SPHERONIZATION

Particles colliding with the wall and being thrown back to the inside of the plate creates a "rope-like" movement of product along the bowl wall.

The granules are discharged by the centrifugal force after the desired spherical shape is obtained.

Air is introduced under the plate (difference from other spheronizers)

The air assist to Remove surface moisture on the particles Mechanically induced fludization

This process can be used to directly spheronize dry powder Act both as mixer or granulator Binding liquid is injected directly in to a mechanically

fludized fine solid particles Friction plate

Propeller like device on the top Perforated base to distribute air through out the

product Air may flow through gap between plate wall and

trailing edge of propaller blade decreasing efficiency Require air filtration system for discharging air Pre treatment of air is needed i.e. heating, cooling, filtration,

humidity control

AIR ASSISTED SPHERONIZING

KEY SPHERONIZING FACTORS◦ Disc speed and load ◦ Disc groove geometry ◦ Disc diameter and speed ◦ Retention time ◦ Product paramaters

Disc Speed◦ There is an optimum disc speed and load for each disc

diameter◦ Momentum too low:

Extrudate not densified sufficiently No spheres formed

◦ Momentum too high (from under loading or disc speed too high): Too much force on the granules Compression of particles within the granules Minimum porosity Granules fracturing

Disc Groove Geometry: Both radial and cross hatched will work

effectively Radial disc had gentler and more controlled

action Radial not suitable for large diameter discs

Disc Diameter: Retention time:

Product Parameters: particles must be plastic enough to allow

deformation during collisions. Also must be strong enough to withstand

collisions with the disc, other particles and the spheronizer wall without breaking up.