On the Drug-Loading Capacity of Pectin Powder for Direct Compression

Abstract

Pectin has lately gained much attention for colon cancer treatment (1–3): it reduces the severity of colon cancer (3), and it is selectively digested by colonic microflora, which can be exploited as a trigger for drug release. Therefore, a pectin matrix potentially serves dual purposes in treatment of colon cancer as drug carrier and/or therapeutic agent itself. We have previously investigated how pectin powders alone behave in direct compression (DC) of tablets (4,5). Pectin is a soft material, which undergoes low degrees of particle rearrangement and fragmentation (5). The degree of methoxylation (DM) was found to have a limited effect on compressibility, but the mechanical strength of the tablets is strongly dependent on both DM and initial particle size. Pectins with DM ≤10 % produce mechanically strong tablets, whereas pectins with DM >50 % produce incoherent compacts. In the present study, a suitable pectin quality is challenged as a matrix former: a model drug material, which will not deform and contribute to bonding and thus increased tablet tensile strength (i.e., “inert”), is mixed in different ratios with pectin powder. Drugs and excipients usually contribute to the formation of tablets, but quartz (SiO2) will not. If coherent tablets can be made of pectin and quartz powder by DC, pectin should also be promising for use as colon-targeting DC matrix tablets containing different drugs. The aim of the current study was to characterize the compaction behavior and mechanical properties of DC tablets made with different ratios of pectin DM 4 % with ultrafine quartz powder.