Lactose Monohydrate CAS 64044-51-5

What is Lactose Monohydrate?

Lactose monohydrate is the crystalline hydrate of milk sugar — a disaccharide of galactose and glucose, C₁₂H₂₂O₁₁·H₂O, with one water molecule locked into the crystal lattice. That water is structural rather than free, which is why the material sits at around 5% water and is still considered a dry excipient.

It is the most widely used filler in solid dose manufacture, and its appeal is unglamorous: it is cheap, it is soluble, it dissolves cleanly in the gut, it tastes faintly sweet, and it has been used for so long that regulators ask no questions about it.

It is supplied in grades defined by how the crystals were processed. Milled and sieved grades, graded by mesh, are for wet granulation and capsule filling. Spray-dried grades carry some amorphous lactose that makes them compressible enough for direct compression. Inhalation grades are closely controlled coarse fractions used as the carrier in dry powder inhalers.

The one real constraint is chemical. Lactose is a reducing sugar, and it reacts with primary amine drugs through the Maillard reaction, browning the tablet and generating degradation products. That single interaction is the main reason a formulation would use anything else.

Why lactose monohydrate specifically

• Soluble and fast-dissolving. Unlike the insoluble fillers, it dissolves completely, which helps dissolution and avoids a residue in the gut.
• Cheap and abundant. It is a by-product of cheese making, so it is one of the least expensive compendial excipients available.
• Grades for every process. Milled for granulation, spray-dried for direct compression, coarse controlled fractions for inhalation — one material covering several unrelated jobs.
• Compresses by fracture. It fractures rather than deforming, which complements MCC's plastic deformation — the reason the two are used together so often.

How Lactose Monohydrate is Manufactured

Lactose is recovered from whey, the liquid left after cheese making. The purification is straightforward; the grade is created afterwards, by how the crystals are processed.

• Whey processing. Whey from cheese manufacture is clarified and the protein removed by ultrafiltration, leaving a permeate rich in lactose.
• Concentration and crystallisation. The permeate is concentrated and cooled under controlled conditions so alpha-lactose monohydrate crystallises. Crystallisation rate sets crystal size and shape.
• Washing and refining. Crystals are washed and, for pharmaceutical grades, recrystallised to remove residual protein, salts and colour. Protein and light-absorbing impurity limits on the certificate come from this step.
• Drying. Dried under conditions that retain the crystal water without converting to the anhydrous or amorphous form.
• Grade creation. Milling and sieving produce the mesh grades; spray drying a slurry produces the directly compressible grade with its amorphous fraction; controlled classification produces inhalation carrier grades.

Typical Commercial Specification

Figures below are representative of pharmacopoeial milled or sieved material. Spray-dried and inhalation grades differ in particle size, flow and amorphous content — tell us the grade or the process and we will quote against it.

Physical & Chemical Properties

Behaviour in the formulation

Lactose is physically straightforward and chemically specific. Four behaviours define how it is used:

• Brittle fracture under compression. It breaks into smaller particles rather than deforming, creating fresh surfaces that bond. This is why it pairs so well with MCC, which deforms instead.
• Fast dissolution. It dissolves completely and quickly, pulling water into the tablet and supporting disintegration and drug release.
• The Maillard reaction. The reducing sugar reacts with primary amines on heating or over time, producing brown discolouration and degradation products. This is the single compatibility question to settle before using it.
• Amorphous content in spray-dried grades. The amorphous fraction gives compressibility but is hygroscopic and can recrystallise over time, which is why spray-dried grades behave less predictably in long-term stability than crystalline ones.
• Inhalation carrier behaviour. In a dry powder inhaler, coarse lactose carries the micronised drug and releases it on inhalation — a purely physical function that depends entirely on particle size and surface texture.

Lactose Grades and the Alternative Fillers

Grade choice follows the process, and filler choice follows the active. Both decisions are made early and are expensive to revisit.

Stated plainly: lactose fractures and dissolves, MCC deforms and does not. Most direct compression formulas use both, because the combination gives binding from one and dissolution and cost from the other. Where lactose is ruled out by an amine interaction, mannitol or a dibasic calcium phosphate usually takes its place rather than MCC alone.

Industries We Supply Lactose Monohydrate To

The same white powder goes to a tablet press, a capsule filler and an inhaler line. What changes between them is the grade, the particle size control and the documentation each sector expects.

Where Lactose Monohydrate is Used

Lactose is bought as a filler in most cases and as a functional carrier in a few. These are the end uses our customers buy it for.

As a tablet and capsule filler

Most tablets are mostly filler, and lactose is the default because it is soluble, cheap and well understood. A typical direct compression blend pairs spray-dried lactose with MCC, so that fracture and plastic deformation both contribute to the compact, with the lactose supplying dissolution and cost control. In wet granulation, milled grades dissolve partially in the granulating fluid and recrystallise as the granule dries, which contributes to granule strength.

In dry powder inhalers

Here lactose is not a filler at all — it is a carrier. Micronised drug particles a few micrometres across cannot flow or be metered, so they are blended onto the surface of much coarser lactose particles that can. On inhalation the drug detaches and travels to the lung while the carrier deposits in the throat. Performance depends on particle size distribution, surface roughness and fines content, which is why inhalation grade lactose is specified far more tightly than any other grade and is not interchangeable with ordinary sieved material.

The amine compatibility question

Lactose is a reducing sugar, so it condenses with primary and secondary amines in the Maillard reaction — the same chemistry that browns toast. In a tablet this shows as yellowing or browning over months and as new degradation peaks in stability testing. If your active carries a primary amine, run the compatibility study early; if it fails, mannitol or dibasic calcium phosphate is the usual replacement, and the formulation work is much cheaper done then than after a stability failure.

Quality Control & Testing

Every lot is released against a batch-specific Certificate of Analysis written against the monograph you nominate, with the particle size data your process depends on reported alongside.

• Identification and specific rotation — compendial identity, confirming the alpha-lactose monohydrate form.
• Water content — Karl Fischer, confirming the monohydrate rather than anhydrous or amorphous material.
• Particle size distribution — by sieve or laser diffraction. The parameter that actually defines the grade, and critical for inhalation material.
• Protein and light-absorbing impurities — the residues of the dairy origin, controlled by the monograph.
• Loss on drying and sulphated ash — free moisture and inorganic residue.
• Microbial limits and specified organisms — including absence of E. coli and Salmonella, which matters more here than for synthetic excipients given the dairy source.
• Heavy metals — elemental impurity control per the applicable monograph.

Common Process Problems & Likely Causes

When lactose causes trouble in a formulation, the cause is usually grade choice or an amine interaction. 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, which the material can pick up.
• Humidity. Crystalline grades are not hygroscopic, but spray-dried grades contain amorphous lactose that is. Keep spray-dried material sealed and in dry storage.
• Microbiological control. As a dairy-derived material it carries microbial specifications. Keep storage dry and clean, and avoid condensation on bags brought from cold stores.
• Dust control. Charge under local exhaust ventilation; fine grades aerate readily.
• Segregation. Store away from amine-containing materials where cross-contamination could initiate browning.
• Shelf life. Typically 36 months in unopened original packing under those conditions. Re-test water content and microbial limits rather than assume.
• Transport classification. Not classified as a dangerous good for transport.

Hazards & Safe Handling

Lactose monohydrate is a food substance with no significant toxicity, used in oral products worldwide. The handling considerations are physical, and the only health point of note concerns the people taking the finished product rather than those handling the raw material.

• Dust explosion risk. Like any fine organic powder, airborne lactose presents a dust explosion hazard. Earth and bond transfer equipment and control ignition sources.
• Nuisance dust. Not toxic, but airborne dust irritates the respiratory tract mechanically. Local exhaust ventilation at charging and dispensing points.
• Patient considerations. Lactose intolerance and, rarely, galactosaemia are patient-facing issues rather than handling hazards, but they drive labelling requirements on the finished product in most markets.
• Dairy allergen. Trace milk protein is controlled by the monograph but the dairy origin is declared, which matters for allergen labelling in food and supplement applications.
• PPE. Dust mask where dust is generated, safety glasses and normal plant workwear. No special chemical protection is required.
• Spill response. Sweep or vacuum avoiding dust clouds. The material dissolves, so wash down after the bulk is removed.
• Environment. Not hazardous to the aquatic environment, though it has a high biological oxygen demand in quantity. Dispose as ordinary industrial waste.
• First aid. Flush eyes with water if dust enters them; move to fresh air if dust inhalation causes irritation.

Regulatory & Compliance Notes

Lactose monohydrate is a compendial excipient with monographs in all the major pharmacopoeias and a long record of regulatory acceptance. 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-NF. We supply against the monograph you nominate, with a compliance statement on the COA.
• BSE/TSE position. Derived from bovine milk, which is not a TSE-risk material, and processed accordingly. Compliance statements supplied as standard, and frequently requested — milk origin is the most common regulatory question about this excipient.
• Allergen declaration. Dairy origin is declared for allergen labelling purposes in food, supplement and pharmaceutical supply chains.
• Patient labelling. Finished products containing lactose carry intolerance warnings in most markets. That is a finished-product obligation, but it begins with your excipient choice.
• Inhalation grade expectations. Material used as a dry powder inhaler carrier is held to far tighter particle size and microbiological specifications, and is treated as a critical material attribute in the filing.
• Excipient GMP expectations. Supply chains for compendial excipients increasingly expect documented GMP and supplier qualification. Tell us what your quality agreement requires.

We Supply Lactose Monohydrate Worldwide

Chelora Chemicals is a supplier and export partner, not a single-plant trader. We ship Lactose Monohydrate 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 BSE/TSE and dairy origin 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 Lactose Monohydrate from Chelora

We are an independent sourcing and supply partner. For lactose that means settling two things at enquiry: the grade and mesh, because crystalline and spray-dried material are not interchangeable, and whether your active carries a primary amine — because if it does, lactose may not be the right filler at all.

• Documentation on every lot. Batch-specific COA written against the nominated monograph, with particle size data reported alongside, plus SDS, TDS and origin statements.
• Samples before commitment. Trial quantities for formulation qualification ahead of a commercial order.
• Quantities. From a single 25 kg bag through to full container loads on contract supply.
• Grade range. Milled and sieved mesh grades, spray-dried direct compression grades and inhalation carrier grades.
• Export experience. Packing, labelling and export documentation handled for sea and air freight.
• Related excipients. MCC, povidone, HPMC 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 lactose usually source several of these alongside it — most tablet formulations use four or five of them together. Consolidating them on one order cuts freight cost and gives you a single point of contact for documentation.