Extrusion Technology

Extrusion Technology

Introduction

Materials used

Process & equipment

Evaluation

Applications

History

• In 18 th century Joseph Brama mfg. of lead pipe by using

extrusion technology • In 19 th century plastic industry More than half products in plastic industry mfg. by using extrusion process

Introduction Definition :

Process of embedding drugs in polymeric carrier

Or Process of converting a raw material into a product of uniform shape an density by forcing it through a die under controlled condition

Advantages

1. Enhance bioavailability of poorly soluble drugs

2. Absence of water & solvents3. Reduced production time 4. Uniform distribution of fine particles 5. Sustained , modified and targeted release

capabilities

Advantages

6. Wide range of dosage forms

7. Stability at varying pH & moisture level

8. No requirement of compressibility of API

9. Better content uniformity

10. Reduced no. of unit operations

Disadvantages

1. Thermal process

2. Flow property of polymer essential

3. Limited no. of polymers

4. High energy input

5. Not useful for Heat sensitive material

Materials used

1. Active ingredients

2. Polymers

3. Plasticizers

4. Other processing aids

Active Ingredients

1. Low solubility & low bioavailability2. Amorphous material 3. Degrade from hydrolysis

E.g.Lopinavir & Ritonavir, Ritonavir etc.

Polymers

1. Drug – polymer must be miscible2. Stability of polymer 3. Theroplasticity of polymer

E.g. PVP & it’s polymers, PEGs, Cellulose ethers and acrylates

Plasticizers

Function :1. Improve processing conditions 2. Improve physical & mechanical

properties 3. Increase flexibility of extrudates 4. Lowers glass transition temperature ( Tg ) of polymers

E.g. Sorbitan monolaurate

Other processing aids

1. Rate modifying agents 2. Antioxidants 3. Chelating agents 4. Thermal lubricants 5. Waxes

Basics of machines

Divided in four steps :1. Feeding system2. Screw & barrel assembly3. Die assembly 4. Vacuum assembly5. Downstream equipment

feeding system

1. Controlled flow 2. Volumetric / gravimetric feeder

Screw & barrel assembly

1. Single / Twin screw 2. Barrel assembly

• Heaters • Water line• Temp. probe

Die assembly

1. Die zone 2. Die nozzle

• Shape the final product

Vacuum assembly

Remove water vapour generated during extrusion

Down stream equipment

Cool, convey & break the extrudates

Types of Extrusion machines

Based on type of screw :1. Single Screw 2. Twin screw

Comparison of single screw vs twin screw

Single Screw Twin Screw Mixing capability less Mixing capability more

More residance time Less residance time

Self wiping not done Self wiping screw profile

Not versatile Versatility

Output less More output

Evaluation

Methods differentiate between solid solution & solid dispersions1. Differential scanning calorimetry ( DSC )2. Thermo gravimetric analysis ( TGA )3. X- ray diffraction method ( XRD )4. IR / NMR spectroscopy5. Microscopy

Differential scanning calorimetry

Process :Extrudates scanned with physical mixture of blend

Use :• Study thermal property of materials• Detects transitions ( M.P., Tg )

Thermo gravimetric analysis ( TGA )

Measure thermal induced weight loss of material

Use :• Study of desolvation & decomposition • Thermal stability

X- ray diffraction method ( XRD )

Principle :Based on Bragg's law

Use :• Characterize crystalline property• Differentiate between solid solution &

solid dispersion

IR & NMR spectroscopy

IR Spectroscopy :• Detect changes in bonding between

functional groups

NMR spectroscopy :• Probe the crystallinity of material

Microscopy

Use :To study crystalline property of extrudates

Applications

• Mask bitter taste of active drugs• Increase drug solubility & dissolution rate • Formation of controlled release dosage

form• Formation of targeted release dosage

forms