Improved Tableting Properties of Ascorbic Acid Via Eutectic Compositions with Sugars

Ascorbic acid (ASC) is commonly used as an anti-oxidant and a dietary supplement due to its radical scavenging properties. The ASC chewable tablet dosage form is regularly prescribed to increase immunity among Covid-19 patients. The main drawback during tableting of ASC is its brittle nature because of interlocking packing arrangement, strong hydrogen bonding between complimentary functional groups and lack of slip planes in its crystal lattice. In order to improve the compaction properties of ASC, sugar and sugar alcohol as coformers with better tableting profile over ASC were introduced. During high throughput cocrystal screening, four eutectic compositions of ASC with glucose (GLU), mannitol (MAN), sucrose (SUC) and lactose monohydrate (LAC) were obtained in an equivalent stoichiometry that offer improved aqueous stability (Palanisamy et al. Front. Chem., 2022, 10, doi: 10.3389/fchem.2022.754269). The binary eutectics (1:1) were confirmed by their lower melting endotherms compared to the individual components and overlapping of those in XRD characterization. The regular (lamellar) microstructures of the ASC-GLU and ASC-MAN eutectics and irregular (acicular or globular) microstructures of the ASC-LAC and ASC-SUC eutectics were confirmed by the optical and scanning electron microscope (SEM) images of the crystallized binary compositions. Similar to ASC, all the eutectic mixtures were proved to non-hygroscopic at 25 ᴼC/80% RH, which is a basic requirement during compaction studies. The eutectics with disaccharides such as ASC-SUC and ASC-LAC improved the tensile strength (tabletibility) of ASC with lower porosity, compared to the corresponding monosaccharide eutectics (ASC-GLU/ASC-MAN). Improved compaction properties of ASC-SUC/LAC eutectics is correlated with higher inter-particulate bonding area and bonding strength.