Disintegrants swelling

Although water penetration is a neeessary first step for disintegration, swelling is probably the most widely aceepted mechanism of action for tablet disintegrants. Indeed, most disintegrants do swell to some extent, but the variability of this property between disintegrants reduces its plausibility as a sole meehanism. 

Polymer Gel - Structure 7.6 Tablet Disintegration, Swelling, Drug 468... 

Tablet Disintegration, Swelling, Drug Release. - In the past few years, studies on polymer matrixes used as controlled release systems (matrix characterization and factors influencing the release process) have been the subject of intense research interest. Different approaches and techniques have been used to understand the release process, in an effort to achieve maximum pharmaceutical effectiveness of the incorporated drug. 

Table II shows data obtained by sequential hexanes and ethanol extractions of the desilylated networks. Attempts to extract the networks prior to desilylation failed because the samples swelled to such a great degree that they lost their mechanical integrity and disintegrated. The amount of hexanes extractable material is less than 3% in all cases which indicates high copolymerization yields. Ethanol extractables were not determined because the presence of the byproducts of the desilylation, which are in the ethanol, would have given artificially high readings.

For most tablets, it is necessary to overcome the cohesive strength introduced into the mass by compression. It is therefore common practice to incorporate an excipient, called a disintegrant, which induces this process. Several types, acting by different mechanisms, may be distinguished (a) those that enhance the action of capillary forces in producing a rapid uptake of aqueous liquids, (b) those that swell on contact with water, (c) those that release gases to disrupt the tablet... 

Although untreated starches do not swell sufficiently, certain modified forms, such as sodium starch glycolate, do swell in cold water and are better as disintegrants. Various cellulose derivatives, including methylcellulose and carboxymethylcellulose, have been used in this role, but with limited success due to the marked increase in viscosity they produce around the dispersing tablet mass. 

In their study of branched PSA, Maniar et al. (1990) found that the molecular architecture of branched polymers affects the release kinetics in a variety of ways. They found that the branched polymers degraded faster than linear PSA of comparable molecular weight (Maniar et al., 1990). They also noted that drug (morphine) release profiles were more characteristic of bulk erosion than surface erosion An initial lag time during which very little drug was released was associated with the time required for water to swell the polymer. This was followed by a period of relatively fast release, which tapered off as the device disintegrated. The polymer matrix lost its mechanical integrity before the release experiment was complete (Maniar et al., 1990). Despite the increase... 

TNF-a can mediate death of sensitive cells via apoptosis or necrosis (necrotic death is characterized by clumping of the nuclear chromatin, cellular swelling, disintegration of intracellular organelles and cell lysis apoptotic death is characterized by cellular shrinking, formation of dense apoptotic masses and DNA fragmentation). 

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