Hydroxypropyl Cellulose|HPC

Hydroxypropyl Cellulose is a derivative of cellulose and it is used as an excipient in different pharmaceutical dosage forms.USP 32 NF-27 defines the HPC as a partially substituted derivative of cellulose and it may contain not more than 0.6% Silica or any other anticaking agent.

Other Names

HPC is also known

• Klucel
• hyprolose
• HPC

Functions Of  HPC

HPC is used as

• Tablet and Capsule Binder.
• As Matrix For Extended Release Formulations.
• Film Former.
• Suspending and Thickening agent

Tablet and capsule binder

HPC or klucel is used as a binder for tablet and capsule formulation for both dry and wet granulation.

 

• In wet granulation, it may be added in dry mixing before kneading and can be activated by addition of solvent.
• It is also used as a binder for wet granulation in the form of solution.
• The concentration of HPC used as a binder is 2-6% for wet and dry granulation.

Note

HPC is water-soluble but when it is added in water it may form a gel at the start and take time to dissolve to form a clear solution.

Following method can be used to form a clear solution of HPC in water in a short period.

For this slurry of HPC is prepared in hot water or glycerin.

Prepare a slurry of HPC in hot water at 50-60°C and don’t exceed the temperature above  60°C. 

Stir the soaking material for a few minutes and maintain the slurry at a temperature, not below 50°C.

Add this slurry in Cold water with slow stirring.

It will produce a clear, lump-free solution in a short period to reduce the binder preparation time of HPC.

  (Ref Ashland)

Also Read: 

GMP vs cGMP and 21 CFR.

Qualification|FAT|SAT|DQ|IQ|OQ|PQ

As Matrix For Extended Release

• Hydroxypropyl Cellulose is used as a control release agent to slow the release of drugs.
• On contact with water, it forms a matrix and then slowly releases the drug.
• The concentration of HPC used as a matrix is 15-35%.
• As the viscosity of HPC increases, the release rate of drug decreases.
• A surfactant added in the solution of HPC increases its viscosity and drug release is decreased.

Film Former

• HPC is used as a film-forming polymer in tablet coating.
• 5% aqueous solution is used for film coating.
• Film formation by HPC is flexible without plasticiser

Suspending and Thickening agent

HPC is also used as a thickening and suspending agent.

Solubility 

• Hydroxypropyl Cellulose is soluble in the water and polar organic solvents.
• It is soluble in the water below 38°C but it is insoluble at a temperature between 40-45°C.

Stability

• An aqueous solution of HPC may promote mould growth so it is recommended to use an antimicrobial agent for aqueous solutions.
• Organic solutions do not promote antimicrobial growth.  

Incompatible

Hydroxypropyl Cellulose is incompatible with Methyl paraben and Propyl Paraben.

Grades Of Klucel

Klucel is available in different grades.

7 viscosity types are as follow

• EL
• E
• L
• J
• G
• M
• H

The product name is expressed by a combination letter system.First letter indicates viscosity type then second letter indicates particle size and at the last letter represent market segment e.g

 Klucel HF Pharm

H represents grade F Pharm to represent pharmaceuticals.

Fine particle size is expressed by X.

Klucel MXF Pharm

(Ref Ashland)

Following are grades of Klucel

• Klucel HF
•  Klucel MF
• Klucel GF
• Klucel JF
• Klucel LF
• Klucel EF

(Ref Handbook of Pharmaceutical Excipients)

Hydroxypropyl Cellulose Low substituted (L-HPC)

Low substituted Hydroxypropyl Cellulose is also known as L-HPC and is the derivative of cellulose which contains less substitution of hydroxypropyl as compared to HPC.

Solubility

HPC is soluble in water but L-HPC swells in water and is insoluble in water.

Other Names

• L-HPC
• Hyprolose
• Low Substituted

Function

Low substituted Hydroxypropyl Cellulose is used as

• Tablet and Capsule Disintegrant.
• Tablet and Capsule Binder.

Grades Of L-HPC

L-HPC is available in different viscosity grades and particle sizes which are as follow,

• LH-11
• LH-21
• LH-31
• LH-B1
• LH-22
• LH-32

LH-11

• LH-11 has long fibrous particles.
• LH-11 is used as a Disintegrant for Direct compression.
• LH-11 is used as an anti-Capping agent for direct compression.

LH-21

• In LH-21 quantity of fibres is less.
• LH-21 is used as Binder in wet granulation
• LH-21 is used as a disintegrant in wet granulation.

Also Read: 

Colloidal Silicon Dioxide|Aerosil

HPMC|Methocel

LH-31

• LH-31 has a small particle size.
• It is used in the extrusion process to produce granules.

LH-B1

• It is non-fibrous.
• Its density is high.
• It is suitable for FBD process and direct compression method.

LH-22

• Give better disintegration.

LH-32

• Give better disintegration.

Incompatibility

•  L-HPC is Incompatible with alkaline substances and formulations containing L-HPC and alkaline substances may result in prolong disintegration time.