Lactose, anhydrous

• BPAnhydrous Lactose
• JPAnhydrous Lactose
• Ph. Eur.Lactose, Anhydrous
• USP–NFAnhydrous Lactose

Anhydrous Lactose NF 60M; Lactopress Anhydrous; lactosum anhydricum; milk sugar; Pharmatose DCL 21; Pharmatose DCL 22; SuperTab 21AN; SuperTab 22AN

O-β-D-Galactopyranosyl-(1→4)-β-D-glucopyranose (mixture of anhydrous β- and α-lactose) · [63-42-3]

C12H22O11 · 342.30

Diluent (filler)

Typical concentrations: — · Dosage forms: Solid

Used as a filler and binder in direct compression and as a diluent in wet granulation and capsule filling. Its low water content makes it suitable for moisture-sensitive drugs. It is also used in lyophilised products and as a carrier in dry powder inhalers.

White to off-white crystalline particles or powder, odourless and slightly sweet. Commercial anhydrous lactose made by roller drying is mainly anhydrous β-lactose, typically about 70–80%, with the rest anhydrous α-lactose.

Water content

≤ 1.0% w/w; typically about 0.5% or less

β-Lactose content

typically about 70–80% (roller-dried grades)

Specific rotation

+54.4° to +55.9° (anhydrous basis, at equilibrium)

Solubility

freely soluble in water (β-lactose dissolves faster than α-lactose); practically insoluble in ethanol and ether

At high relative humidity anhydrous lactose can take up water and partly convert to α-lactose monohydrate, which may increase tablet weight and hardness on storage. It may brown in warm, damp conditions. Store in a well-closed container in a cool, dry place.

As a reducing sugar it undergoes Maillard reaction with primary amines, and also with secondary amines more slowly, giving brown products. Incompatible with strong oxidising agents.

β-Anhydrous lactose is made by roller drying a concentrated lactose solution at a temperature above about 93.5 °C, at which the β-form crystallises, followed by milling and sieving. Anhydrous α-lactose is obtained by thermal or chemical dehydration of α-lactose monohydrate.

Widely used and regarded as non-toxic. People with lactase deficiency may have gastrointestinal symptoms after large amounts of lactose, although the quantities in most tablets are too small to matter for most patients.

Observe normal precautions for the quantity handled; eye protection and a dust mask are recommended. Fine lactose dust can form explosive mixtures with air.

Lactose is GRAS listed. Anhydrous lactose is included in the FDA Inactive Ingredient Database (oral capsules and tablets; inhalation and other preparations) and in non-parenteral medicines licensed in Europe.

Lactose monohydrate; lactose, spray-dried; lactose, inhalation; anhydrous lactose and microcrystalline cellulose.

Anhydrous lactose compacts mainly by brittle fracture, so its tabletability is little affected by lubricant level or blending time. Tablets made from it may slowly increase in hardness at high humidity, which should be checked in stability studies.