Lactose SR Granules are pharmaceutical granules based on lactose and developed for sustained-release or controlled-release formulation applications when the finished granule system has been specifically designed and validated for prolonged release. Lactose is an established pharmaceutical excipient commonly used as a diluent or filler, while the sustained-release characteristics of a finished granule system generally depend on the complete formulation and its release-controlling technology.
Lactose is available in different forms, including lactose monohydrate and anhydrous lactose. The current USP-NF maintains separate monographs for these two materials, making the exact lactose form an important part of product identification.
Lactose SR Granules are granulated pharmaceutical systems intended for sustained-release formulation development. The granules may contain lactose as a filler or structural excipient together with other formulation components responsible for controlling the release rate.
The designation SR should therefore describe the finished product or formulation system, rather than implying that lactose itself is a sustained-release polymer.
Sustained-release granules can use different approaches, including polymeric matrix systems, functional coatings, hydrophilic matrices, hydrophobic matrices or combinations of release-controlling excipients.
Lactose is a carbohydrate widely used in pharmaceutical formulations. It can function primarily as a diluent or filler and can contribute to the bulk and physical structure of oral solid formulations.
USP-NF separately defines Lactose Monohydrate and Anhydrous Lactose. Lactose Monohydrate is the monohydrate of O-β-D-galactopyranosyl-(1→4)-α-D-glucopyranose, while Anhydrous Lactose consists of β-lactose or a mixture of β- and α-lactose.
The selected lactose form can influence moisture, density, crystallinity and processing characteristics.
A sustained-release formulation is designed to modify the rate at which an incorporated active ingredient becomes available. For granules, this can be achieved through a controlled-release matrix, functional polymer coating, or a combination of formulation technologies.
Research has demonstrated the use of lactose together with release-controlling polymers in extended-release granule systems. For example, published work on extended-release granules used ethylcellulose and HPMC together with lactose, with the formulation components influencing release kinetics.
Another formulation study reported polymer-granulated lactose systems using polymers such as ethylcellulose and acrylic polymer dispersions to provide controlled-release matrix properties.
Therefore, the sustained-release performance of Lactose SR Granules should be attributed to the complete formulation and release-control system rather than lactose alone.
Controlled granule characteristics are important for consistent pharmaceutical processing and finished-product performance.
Depending on the actual product specification, Lactose SR Granules can be evaluated for:
These parameters should be controlled according to the actual approved product specification.
Sustained-release granules may use different release-control mechanisms.
A matrix system can incorporate lactose together with a hydrophilic or hydrophobic release-controlling material. After exposure to dissolution medium, the matrix can control liquid penetration and active-ingredient diffusion.
A coated granule system can use a functional polymer coating to regulate the movement of the incorporated material into the surrounding medium.
The selection of the technology depends on the active ingredient, target release profile, dosage form and formulation requirements.
Lactose can participate in controlled-release formulations as a water-soluble excipient that affects the structure and porosity of a matrix or granule system.
In an extended-release formulation, lactose can influence the accessibility of the dissolution medium and the internal structure of the formulation. Its effect depends on its concentration, particle characteristics and interaction with other formulation components.
Published research has demonstrated that lactose can influence release behavior when combined with release-controlling materials such as ethylcellulose and HPMC.
Consequently, the final release profile should always be established experimentally for the complete formulation.
The exact lactose form should be stated clearly on the product page.
Lactose Monohydrate and Anhydrous Lactose are separate USP-NF materials.
FCC identifies lactose as occurring in anhydrous form, as a monohydrate, or as a mixture of forms depending on preparation. FCC gives the anhydrous molecular weight as 342.30 g/mol and the monohydrate molecular weight as 360.32 g/mol.
This difference is important when defining the Product Data and moisture specifications for Lactose SR Granules.
Particle size can influence granule surface area, coating characteristics, flow and dissolution behavior.
Bulk density and tapped density can also influence handling, filling and packing characteristics.
For an SR granule system, particle-size distribution can additionally affect the surface area available for release and therefore may influence dissolution behavior when other formulation parameters remain constant.
Because these properties are grade-specific, values such as D50, bulk density or tapped density should only be published when supported by the actual product specification or CoA.
The defining characteristic of an SR granule system is its controlled release profile.
Dissolution testing is therefore a critical product-specific quality attribute. Depending on the formulation, the test may include multiple sampling points over a defined period.
The exact dissolution medium, apparatus, sampling times and acceptance criteria depend on the product specification and formulation design.
Generic statements such as “12-hour release,” “24-hour release,” or a specific percentage released at a particular time should not be used unless supported by actual product data.
Quality control should distinguish between the underlying lactose specification and the finished SR granule specification.
The lactose component can be evaluated for identification, lactose content, moisture, residue on ignition, optical rotation and other applicable pharmacopoeial characteristics.
The finished SR granules may additionally require:
The exact tests depend on the finished product.
Lactose SR Granules can be considered for:
The final application depends on the formulation composition and validated release characteristics.
During formulation development, Lactose SR Granules can be evaluated for compatibility with release-controlling polymers, particle size, density, moisture and flow.
The formulation may additionally be evaluated for dissolution profile, release kinetics, granule integrity and physical stability.
Because different active ingredients have different solubility and permeability characteristics, a unive
| Parameter | Specification |
|---|---|
| Appearance | white to off-white crystalline powder |
| Identification | IR & HPLC compliant |
| Assay (HPLC) | 98.0% – 102.0% |
| Loss on Drying | NMT 1.0% |
| Residue on Ignition | NMT 0.1% |
| Heavy Metals | NMT 10 ppm |
| Individual Impurity | NMT 0.5% |
| Water Content | NMT 1.0% |