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Product : Hypromellose Phthalate

Hypromellose Phthalate also known as HPMC-P or Hydroxy Propyl Methyl Cellulose Phthalate or Cellulose,2-hydroxypropyl methyl ether, phthalic acid Ester.
CAS NO (9050-31-1)



Test HP-55 HP-55S HP-50
Dissolving pH Starts @ 5.5 Starts @ 5.5 Starts @5.0
Labelled Viscosity@20C 40 cst 170 cst 55 cst
Viscosity in cst@20C 32cst-48cst 136cst – 204 cst 44cst – 66cst
Nominal Phthalyl content 31% 31% 24%
Phthalyl content 27.0% - 35.0% 27.0% - 35.0% 21.0% - 27.0 %
& Solubility
Conforms Conforms Conforms
Identification Conforms Conforms Conforms
Water content NMT 5.0% NMT 5.0% NMT 5.0%
Sulphated Ash NMT 0.20% NMT 0.20% NMT 0.20%
Chloride NMT0.07% NMT0.07% NMT0.07%
Heavy Metals NMT 0.001% NMT 0.001% NMT 0.001%
Free Phthalic Acid NMT 1.0% NMT 1.0% NMT 1.0%


HPMC-P i.e. Hypromellose Phthalate has higher moisture barrier property. Thus less prone to hydrolysis due to humidity.

Different grades are available to correlate required pH dissolution in Intestine i.e. from pH 5.0 to pH 5.5. This is achieved by controlled Variation in phthalyl content. Two types of pH variations in solubilities are available. HP-55, HP-55S & HP-50. Selection of required Grade of HPMC-P is made according to the requirements of formulations. Grade HP-55S is a special type of HP-55 having difference in molecular Weight and higher simulated gastric fluid resistance and viscosity.

HP-55 is well recognized and applied as a general enteric coating agent, is well accepted in pharma industries.

HP-55S, due to its higher molecular weight and higher degree of Polymerization w.r.t. HP-55, has higher viscosity, higher mechanical Strength of film and higher resistance to simulated gastric fluid of coated Formulation.This gives less percentage use in coating for tablets,gives better Strength to fragile tablets or granules or pellets.

HP-50, can be used to dissolve the tablets at lower pH in duodenam (pH 5.0), first part of the small intestine.

All the grades are available in BP/USPNF/EP. It can also be made and Supplied as per other recognized pharmacopeia.


  • Film coating of tablets,capsules and pellets
  • Enteric coating of tablets,pellets and capsules
  • Sustained release formulations
  • Delayed release formulations
  • Pellet coating of medical formulation
  • Taste masking of the tablets

Advantages of film coating:

  • Soothens pelletibility by masking odor and smell.
  • Easy to swallow.
  • Enhances product appearance.
  • Protection of formulations from air oxidation,moisture and light.
  • Improves efficacy of the drug.
  • Prevents gastric cell irritation due to drugs.
  • Drug will not get destroyed due to acidic pH of the stomach, thus better medical treatment to the patients.