Carboxymethylstarches in Wet Granulation

Abstract

Commercialized carboxymethystarches (CMS) are both carboxyme-thylated and cross linked potato starch.

The influence of carboxymethylation and cross linkage on the disintegrating properties of starch are studied.

Tablets are made with acetaminophen as drug, Emcompress as diluant, Magnesium stearat as lubricant, and potato starch or its derivatives as disintegrants.

Tablets are prepared by direct compression or by wet granulation with the disintegrant intervening only in internal phasis.

Five disintegrants were studied, with two different concentrations:

native potato starch

potato starch simply cross linked

potato starch simply carboxymethylated

two potato starches both cross linked and carboxymethylated at two different degrees

Compressibility of powders blending and grain for compression are discussed.

The hardness, the tablet disintegration and the rate of drug dissolution are studied.

The results showed that the simply carboxymethylated starch has a totally different behaviour after direct compression or wet granulation. The poor results after wet granulation could be imputed to the bursting of starch granules during grain drying. Since it has lost its granular structure, the carboxymethylated starch will only allow a poor disintegration and a slow dissolution of the drug.

A very similar behaviour of native and simply cross linked starch: the results of which are bad for tablets either prepared by wet granulation or direct compression.

A very similar behaviour of the starches both carboxymethylated and cross linked, allowing a very good disponibility, either with tablets prepared by direct compression or wet granulation. These experiments prove :

the need for an sufficient cross linkage for CMS in a wet granulation process