Alginate-based matrix tablets for drug delivery

ABSTRACT

Introduction

As a nature-derived polymer with swelling and gelling properties, alginate has found wide biopharma-relevant applications. However, there is comparatively limited attention on alginate in tablet formulations. Therefore, this review aimed to provide an overview of the applications of alginate in solid dosage form formulations.

Areas covered

This review outlines the role of alginate for oral sustained release formulations. For better insights into its application in drug delivery, the mechanisms of drug release from alginate matrices are discussed alongside the alginate inherent properties and drug properties. Specifically, the influence of alginate properties and formulation components on the resultant alginate gel and subsequent drug release is reviewed. Modifications of the alginate to improve its properties in modulating drug release are also discussed.

Expert opinion

Alginate-based matrix tablets is useful for sustaining drug release. As a nature-derived polymer, batch consistency and stability raise some concerns about employing alginate in formulations. Furthermore, the alginate gel properties can be affected by formulation components, pH of the dissolution environment and the tablet matrix micro-environment pH. Conscientious efforts are pivotal to addressing these formulation challenges to increase the utilization of alginate in oral solid dosage forms.

KEYWORDS:

• Alginate
• drug delivery
• matrix tablet
• sustained release

Article highlights

• A matrix tablet formulated with hydrophilic polymers, is one among the various drug delivery systems for sustaining drug release over an extended period to improve therapeutic efficacy and reduce dosing requirement, hence adding convenience for better patient compliance toward better disease management.

• When hydrated, alginate forms a gelatinous layer which acts as a barrier to drug diffusion and slows down water permeation into the dosage form.

• As a pH sensitive hydrogel, the behavior of alginate in the gastric environment differs from that in the intestinal tract and requires careful consideration in the design of alginate-based dosage forms.

• Drug release from alginate-based matrix tablets can be influenced by alginate properties (particle size, viscosity, mannuronic acid to guluronic acid ratio), drug properties (solubility, molecular weight, particle size, drug load), tablet properties (porosity, hardness) and formulation factors (amount of alginate, type of cations, micro-environmental pH, other release modifying agents).

• Modifying the micro-environmental pH is useful to overcome lamination of the gel layer formed from alginate hydration in an acidic environment.

• Alginate modifications (e.g. co-processing, polymer grafting and interpenetrating polymeric network formation) are valuable in improving alginate properties for sustaining drug release.

Declaration of interests

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

This paper was funded by GEA-NUS Pharmaceutical Processing Research Laboratory, National University of Singapore.