Disintegration, drug release

Starch is often cited as a filler, but it is more commonly used in its dry state as a disintegrating agent. However, modified starches such as StaRx 1500 and National 1551 (partially hydrolyzed, or pregelatinized starch) are marketed for direct compression and appear to offer the advantage of substantial mechanical strength and rapid drug release. 

Pressure-controlled Disintegration of the drug release dosage form in the colon... 

A.M. Molokhia, Effect of storage on crushing strength, disintegration and drug release from mixed tablet bases. Int. J. Pharm., 22 (1984) 127. 

Batch size (kg) Enteric test (ET) Stressed enteric test (SET) Disintegration time in buffer, pH = 6.8 % Drug released after 2 hours in 0.1 NHC1( ) % Drug released after 90 min in buffer pH = 6.8... 

The degree of ionization under physiologic conditions Product formulation characteristics Disintegration and dissolution rates for solid dosages Drug release characteristics for timed-release preparations Patient factors... 

The second point is that the S-shapes of many of the release curves in this study indicate a biphasic pattern of drug release. This was also observed by Wakiyama et al (7-91. who used scanning electron microscopy to demonstrate that the second rise in the release rate was due to disintegration of the polylactide microspheres. 

A sustained drug release is favourable for drugs with short elimination half-life. It can be controlled by hydration and diffusion mechanisms or ionic interactions between the drug and the polymeric carrier. In the case of diffusion control the stability of the carrier system is essential, as its disintegration leads to a burst release. Therefore, the cohesiveness of the polymer network plays a crucial role in order to control the release over several hours. Due to the formation of disulphide bonds within the network thiomers offer adequate cohesive stability. Almost zero-order release kinetics could be shown for insulin embedded in thiolated polycarbophil matrices (Clausen and Bernkop-Schnurch 2001). In the case of peptide and protein drugs release can be controlled via ionic interactions. An anionic or cationic polymer has to be chosen depending... 

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