Hydroxypropyl Methylcellulose (HPMC) CAS 9004-65-3

What is Hydroxypropyl Methylcellulose (HPMC)?

Hypromellose — hydroxypropyl methylcellulose — is cellulose with some of its hydroxyl groups converted to methyl ethers and some to hydroxypropyl ethers. The two substitutions together turn an insoluble natural polymer into a water-soluble one whose behaviour can be tuned across an enormous range.

That range is the point. Low-viscosity grades dissolve quickly and form thin clear films, so they coat tablets. High-viscosity grades hydrate into a gel layer that controls how fast a drug leaves the tablet, so they build controlled-release matrices. Same CAS number, completely different jobs.

Two numbers identify a grade and both must be specified. The substitution type — 2208, 2906 or 2910, corresponding to the K, F and E series — sets the methoxy and hydroxypropoxy content and therefore the gelation and solubility behaviour. The viscosity of a 2% solution, from a few millipascal-seconds to a hundred thousand, sets everything else.

Commercially HPMC is a high-volume excipient across film coating, controlled release, vegetarian capsule shells, ophthalmic products and tablet binding, and it is also used widely in food and construction. The pharmaceutical grades are distinguished by their monograph compliance and their much tighter microbial and residual limits.

Why hypromellose specifically

• One polymer, many jobs. Coating, binding, controlled release, capsule shells and ophthalmic viscosity, all from the same chemistry at different grades — which simplifies supplier qualification considerably.
• Predictable gel-layer release. High-viscosity K grades hydrate into a gel that controls drug release reproducibly, and the release profile can be tuned by grade and by level.
• Non-ionic and broadly compatible. Being non-ionic, it tolerates a wide pH range and most salts and actives, unlike the ionic polymers.
• Plant-derived and vegetarian. Capsule shells and coatings made from it avoid the animal-origin question entirely, which matters commercially in a growing number of markets.

How HPMC is Manufactured

HPMC is made by etherifying alkali cellulose with two reagents. The ratio between them is what creates the substitution types, and chain length control is what creates the viscosity grades.

• Alkali cellulose preparation. Purified cellulose from wood pulp or cotton linters is treated with sodium hydroxide to swell the fibre and activate the hydroxyl groups.
• Etherification. Methyl chloride and propylene oxide react with the alkali cellulose to install methoxy and hydroxypropoxy groups. Their relative amounts determine the substitution type — 2208, 2906 or 2910.
• Viscosity control. Chain length is controlled during and after reaction, setting the 2% solution viscosity that defines the grade. E5 and K100M differ here, not in substitution chemistry.
• Washing and purification. Salts and reaction by-products are washed out. Residual chloride and ash on the certificate reflect how thoroughly this ran.
• Drying, milling and classification. Dried and milled to a defined particle size, which affects dispersion behaviour and, in matrix tablets, the reproducibility of the release profile.

Typical Commercial Specification

Figures below are representative of hypromellose 2910 (E series) at low viscosity, the typical film coating grade. Substitution type and viscosity together define the grade — tell us both, or tell us the application and we will advise.

Physical & Chemical Properties

Behaviour in the formulation

HPMC is physically active and chemically inert, and almost everything it does traces back to how it hydrates:

• Hydration and gel layer formation. On contact with water the surface hydrates into a viscous gel layer. In a matrix tablet that layer controls drug diffusion and tablet erosion — the whole mechanism of controlled release.
• Film formation. Low-viscosity grades form clear flexible films from aqueous solution, giving a coating that protects, masks taste and carries colour without delaying disintegration.
• Thermal gelation. Solutions gel on heating and clear again on cooling. This is why HPMC capsule shells are made by a thermogelation process and why dispersion is done in hot water.
• Binding. Mid-viscosity grades work as granulation binders, giving harder granules than povidone at the same level.
• Viscosity building. In liquid and ophthalmic formulations it increases viscosity and residence time without irritation.

HPMC Grades and the Alternative Polymers

Choosing an HPMC grade is choosing a viscosity and a substitution type together. Choosing between polymers is about release mechanism and about whether ionic character is acceptable.

Stated plainly: the E series coats and the K series controls release. Within the K series, higher viscosity gives a more robust gel layer and slower release, which is why K4M, K15M and K100M are effectively a dial for release rate. Changing between them changes the product, not just the supplier.

Industries We Supply HPMC To

The same white powder goes to a coating pan, a controlled-release line and a capsule machine. What changes between them is the grade, the particle size and the documentation each sector expects.

Where HPMC is Used

HPMC does several unrelated jobs depending on grade, which is why most solid dose plants buy more than one. These are the end uses our customers buy it for.

In film coating

A standard aqueous coating system is a low-viscosity HPMC such as E5 or E15, a plasticiser, a pigment or opacifier and water, sprayed to 2 to 4% weight gain. The polymer has to dissolve fast enough to spray at a workable solids content, form a continuous film as the water evaporates, and dissolve quickly in the gut so it does not delay disintegration. Low viscosity is what makes all three possible, which is why coating grades and matrix grades are not interchangeable in either direction.

In controlled-release matrices

Press a high-viscosity K grade into a tablet with the active and the surface hydrates on contact with fluid, forming a gel layer through which the drug must diffuse and which itself slowly erodes. The release profile depends on the grade, the polymer level, the drug's solubility and the particle size of the polymer — which is why controlled-release formulators specify particle size even though it says nothing about chemical purity. A grade change here is a bioequivalence question, not a procurement one.

In capsules and ophthalmics

HPMC capsule shells are made by dipping heated pins into a polymer solution that gels on the hot surface — the thermal gelation behaviour put to direct use. They are the standard vegetarian alternative to gelatin and have lower moisture content, which suits hygroscopic fills. In ophthalmic products, low concentrations increase viscosity and residence time on the eye surface without irritation, which is why hypromellose appears in so many artificial tear formulations.

Quality Control & Testing

Every lot is released against a batch-specific Certificate of Analysis written against the monograph you nominate, with the functional parameters that drive your process reported alongside the compendial tests.

• Methoxy and hydroxypropoxy content — the figures that define the substitution type, and the ones a bare viscosity number leaves out.
• Apparent viscosity — measured on a 2% solution under defined conditions. The defining grade parameter.
• Loss on drying — moisture, which affects both dispersion behaviour and weight-based charging.
• pH and appearance of solution — compendial purity confirmation, and a practical check on dissolution quality.
• Particle size distribution — reported where specified, because it affects hydration rate and therefore release reproducibility.
• Residue on ignition and heavy metals — inorganic residue and elemental impurity control.
• Microbial limits — total aerobic count, yeasts and moulds, and absence of specified organisms per the monograph.

Common Process Problems & Likely Causes

When HPMC causes trouble in a plant, the cause is usually dispersion technique or a grade mismatch rather than a lot defect. This table is the shortcut our technical desk works through before anyone opens a complaint file.

Packaging, Storage & Shipping

• Standard packing. 25 kg net in multi-ply paper bags with polyethylene inner liners, palletised and shrink-wrapped.
• Storage. Cool, dry and well-ventilated, off the floor and away from strong odours. The material is stable but takes up moisture from humid air.
• Dispersion technique. Disperse in hot water above about 80 °C, where it does not dissolve, then cool with stirring. Adding it to cold water produces lumps that are very slow to break down.
• Moisture. Reseal liners after opening. Moisture uptake affects both the weight you charge and the speed of dispersion.
• Dust control. A light powder that aerates readily. Charge under local exhaust ventilation.
• Cross-contamination. Store away from strongly scented materials, which it can pick up.
• Shelf life. Typically 36 months in unopened original packing under those conditions. Re-test viscosity and loss on drying rather than assume.
• Transport classification. Not classified as a dangerous good for transport.

Hazards & Safe Handling

Hypromellose is a well-tolerated excipient with no significant toxicity by any normal route, used in oral, ophthalmic and topical products. The handling considerations are physical rather than toxicological.

• Dust explosion risk. Like any fine organic powder, airborne HPMC in sufficient concentration presents a dust explosion hazard. Earth and bond transfer equipment and control ignition sources.
• Slip hazard. This one is specific to HPMC and often underestimated. Spilled powder that gets wet becomes extremely slippery. Clean spills dry and keep water away from them.
• Nuisance dust. Not toxic, but airborne dust irritates the respiratory tract mechanically. Local exhaust ventilation at charging points.
• Eye contact. Mechanical irritation only. Safety glasses during dispensing and transfer.
• PPE. Dust mask where dust is generated, safety glasses and normal plant workwear. No special chemical protection is required.
• Spill response. Sweep or vacuum dry, avoiding dust clouds, and do not wash down until the bulk is removed.
• Environment. Not hazardous to the aquatic environment. Dispose as ordinary industrial waste in line with local regulations.
• First aid. Flush eyes with water if dust enters them; move to fresh air if dust inhalation causes irritation.

Regulatory & Compliance Notes

Hypromellose is a compendial excipient and an approved food additive, with monographs in all the major pharmacopoeias. Because obligations differ by territory and use, the notes below are orientation rather than legal advice — confirm your own position with your regulatory adviser.

• Pharmacopoeial status. Monographs in IP, BP, Ph. Eur. and USP, with the substitution type forming part of the compendial identity. We supply against the monograph you nominate.
• Grade on the filing. Both substitution type and viscosity are normally specified in a marketing authorisation, particularly for controlled-release products, where a change is a bioequivalence question rather than a purchasing decision.
• Food additive status. Permitted as E464 in food applications in the major regulatory systems, within the conditions that apply in your market.
• BSE/TSE and vegetarian position. Derived from wood pulp or cotton linters, with no animal-derived material. Statements supplied as standard, which is the basis of the vegetarian capsule claim.
• Excipient GMP expectations. Supply chains for compendial excipients increasingly expect documented GMP and supplier qualification. Tell us what your quality agreement requires.
• Halal and kosher. Certification available on request for markets and customers that specify it.

We Supply HPMC Worldwide

Chelora Chemicals is a supplier and export partner, not a single-plant trader. We ship Hydroxypropyl Methylcellulose (HPMC) from India to customers across Asia, Europe, the Middle East, Africa, and North and South America, handling the export documentation, pharmacopoeial documentation and freight so the material arrives ready to use.

• Incoterms. EXW, FOB, CIF, CFR and DAP quoted to suit your purchasing terms and freight arrangements.
• Ports. Regular shipments through Nhava Sheva (JNPT) and Mundra, with other Indian ports arranged where it suits the routing.
• Documentation. Commercial invoice, packing list, certificate of origin, COA, SDS and the substitution type, viscosity and BSE/TSE statements issued as a complete set.
• Flexible volumes. A single bag for laboratory qualification, through LCL consolidations, up to repeat full container loads on a supply contract.
• Supply continuity. Because we are independent of any one producer, a plant turnaround or a shipping disruption at one source does not have to become your stock-out.

Buying HPMC from Chelora

We are an independent sourcing and supply partner. For HPMC that means settling two things at enquiry: the substitution type and the viscosity, because a grade is not identified without both, and whether the material is coating or controlling release — because those are different products from the same CAS number.

• Documentation on every lot. Batch-specific COA written against the nominated monograph, with substitution type, viscosity and particle size where specified, plus SDS, TDS and supporting statements.
• Samples before commitment. Trial quantities for coating or dissolution qualification ahead of a commercial order.
• Quantities. From a single 25 kg bag through to full container loads on contract supply.
• Grade range. E5, E15, E50, K100LV, K4M, K15M and K100M, with other grades sourced on request.
• Export experience. Packing, labelling and export documentation handled for sea and air freight.
• Related excipients. MCC, lactose monohydrate, povidone and magnesium stearate from one supplier, which keeps a whole solid dose formula on a single order.

How ordering works

• Send the enquiry. Product, grade or pharmacopoeia standard, quantity, destination port and the Incoterm you buy on. If you have a spec sheet, attach it — it saves a round trip.
• We quote. Price, lead time, packing and a sample COA, normally within one working day.
• Sample and qualify. For first orders or critical applications, we send a trial quantity so your lab can sign off before you commit.
• Confirm the order. Proforma invoice issued; payment terms agreed against the volume and the relationship.
• Production and QC. Material allocated and released against a batch-specific COA, with a pre-shipment sample where the application calls for it.
• Ship and document. Packed, labelled and loaded with the full export document set, and tracked through to arrival.

Related Pharmaceutical Excipients & Intermediates

Buyers of HPMC usually source several of these alongside it. Consolidating them on one order cuts freight cost and gives you a single point of contact for documentation.