Hydroxypropyl Methylcellulose|HPMC

Hydroxypropyl Methylcellulose is a derivative of cellulose and is a semisynthetic excipient used in oral liquid, ophthalmic, nasal, topical and oral solid dosage form preparations.

 It is tasteless, odourless granular or fibrous powder.

Hydroxypropyl Methylcellulose is commonly known as 


  • HPMC

  • Hypromellose

  • Methocel


Numbering System

  • USP 32 defines the substitution  by numbering systems for HPMC or Hypromellose.

  • A 4 digit numbering system is used.

  •  First two digits show the %age of the methoxy group.

  •  Last 2 digits show the %age content of the hydroxypropoxy group.


Examples

  • Hypromellose 2208

  • Hypromellose 2906

  • Hypromellose 2910


2208 is known as K grade and 2910 is known as E grade


Nomenclature

  • For HPMC the initial alphabets K,E, F represent methoxyl hydroxypropyl substitutions in the polymer.

  • After alphabet the  numeric value represents the viscosity of HPMC in millipascal second of that specific grade determined at 2% concentration in water at 20 °C.


  • M represent 1000

  • LV is Low Viscosity

  • VLV is a Very Low Viscosity


Example

  • HPMC K 100 M

  • HPMC K 100 LV


Grades 


HPMC is available in different viscosity grades and molecular weight.

Different grades areas


  • K100 M

  • K100 LV

  • E 15 LV

  • E5

  • VLV


Uses of  HPMC

HPMC  is used as


  • Tablet & Capsule Binder

  • Film-Forming Agent

  • Thickening Agent 

  • Viscosity Enhancer

  • Thickening Agent

  • Matrix forming Agent for

    • Sustained release

    • Modified Release

    • Extended-Release

  • Wetting agent for contact lenses.

  • In Nasal preparations. 0.1%


Also Read: 


HPMC As Binder

  • 2-5% w/w solution of HPMC is used as a tablet and capsule binder for wet granulation and dry granulation.


As Film Former

  • 2-20% w/w HPMC solution is used in tablet coating to mask the unpleasant taste and it form the layer of polymer over the tablet.

  • Low viscosity grades are used for aqueous solution coating.

  • High viscosity grades are used for organic solvent coating.


As Matrix

  • HPMC is used in tablet and capsules dosage form to modify the drug release profile.

  • High viscosity grades of HPMC are used in 10-80% concentration for tablet and capsule formulations to form a matrix.

  • The matrix is formed on contact with the water and it entraps the drug and alters its release according to requirements.


In Oral liquids

  • HPMC is used to increase the viscosity of oral liquid formulations.

  • It is also used s a thickening agent at concentration 0.25-5%.


In Topical Preparations

  • HPMC is used to increase the viscosity of topical formulations.

  • It acts as a thickening agent in topical preparations.


In Ophthalmic Preparations

  • HPMC is used in ophthalmic preparations because it forms a more clear solution than methylcellulose

  • it is used in artificial tears and to enhance the viscosity of eye drops and used concentration is 0.45-1%.

  • HPMC in liquid preparations may promote microbial growth so antimicrobial agents should be added in ophthalmic preparations.


Solubility

  • It is soluble in cold water and insoluble in hot water.


Storage


  • HPMC absorbs moisture from the environment so it should be stored in a tightly closed container.