Functional Category
Directly compressible tablet excipient; dry powder inhaler carrier; lyophilization aid; tablet and capsule diluent; tablet and capsule filler.
Applications in Pharmaceutical Formulation
Anhydrous lactose is widely used in direct compression tableting applications, and as a tablet and capsule filler and binder. Anhydrous lactose can be used with moisture-sensitive drugs due to its low moisture content. It may also be used in intravenous injections.See also Lactose, Inhalation; Lactose, Monohydrate; Lactose,Spray-Dried
Description
Anhydrous lactose occurs as white to off-white crystalline particles or powder. Several different brands of anhydrous lactose are commercially available which contain anhydrous b-lactose and anhydrous a-lactose. Anhydrous lactose typically contains 70–80% anhydrous b-lactose and 20–30% anhydrous a-lactose.
Stability and Storage Conditions
Mold growth may occur under humid conditions (80% RH and above). Lactose may develop a brown coloration on storage, the reaction being accelerated by warm, damp conditions; see Section 12. At 808C and 80% RH, tablets containing anhydrous lactose have been shown to expand 1.2 times after one day.(2) Lactose anhydrous should be stored in a well-closed container in a cool, dry place
Incompatibilities
Lactose anhydrous is incompatible with strong oxidizers. When mixtures containing a hydrophobic leukotriene antagonist and anhydrous lactose or lactose monohydrate were stored for six weeks at 408C and 75% RH, the mixture containing anhydrous lactose showed greater moisture uptake and drug degradation.(3) Studies have also shown that in blends of roxifiban acetate (DMP-754) and lactose anhydrous, the presence of lactose anhydrous accelerated the hydrolysis of the ester and amidine groups.(4) Lactose anhydrous is a reducing sugar with the potential to interact with primary(5) and secondary amines(6) (Maillard reaction) when stored under conditions of high humidity for extended periods.
Safety
Lactose is widely used in pharmaceutical formulations as a diluent and filler-binder in oral capsule and tablet formulations. It may also be used in intravenous injections. Adverse reactions to lactose are largely due to lactose intolerance, which occurs in individuals with a deficiency of the intestinal enzyme lactase, and is associated with oral ingestion of amounts well over those found in solid dosage forms.