Introduction To Peletization And Sperunization

INTRODUCTION TO PELLETIZATION

PELLETS 

Geometrically defined agglomerates of size range 0.5 -0.15 mm.

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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 

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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

INTRODUCTION 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. 

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

DESIGN OF FRICTION PLATE

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Two types 

Cross hatch pattern 

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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 

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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

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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 

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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

PROCESS OF SPHERONIZATION      

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.

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 ASSISTED SPHERONIZING Air is introduced under the plate (difference from other spheronizers)  The air assist to 

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This process can be used to directly spheronize dry powder  

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Act both as mixer or granulator Binding liquid is injected directly in to a mechanically fludized fine solid particles

Friction plate  

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Remove surface moisture on the particles Mechanically induced fludization

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

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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

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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: 

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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.