Compressibility studies of α- amylase

Manu Sharma, Vinay Sharma, Dipak K Majumdar


Proteins possess greater biochemical and structural complexity compared to conventional drug based pharmaceuticals. In the present study, we investigated the effect of compression force on the tablet properties, primarily the enzyme activity and the percolation threshold to have more information of behaviour of α- amylase powder under compaction along with detection of mixture range in which enzyme is protected by the excipients. The results showed that carrageenan, tragacanth and agar provided the maximum protection to enzyme activity compared to microcrystalline cellulose and dicalcium phosphate dihydrate on compaction. However stability studies indicated the highest loss of enzyme activity with carrageenan, tragacanth and agar. The compressibility studies of different binary mixtures of α- amylase with microcrystalline cellulose indicated that α- amylase behaves like a brittle substance. The application of percolation theory on the relationship between the critical density as a function of enzyme activity and mixture composition revealed the presence of percolation threshold for binary mixture. α- Amylase – microcrystalline cellulose mixture composition showed significant percolation threshold at 37.23 % (w / w) α- amylase loading. Microcrystalline cellulose provided higher protection during stability study. However, higher concentrations of microcrystalline cellulose, probably as dominant particles do not protect the enzyme with their plastic deformation. Below the percolation threshold i.e. 37.23 % (w / w) α- amylase amount in mixture with plastic excipient, activity loss increases strongly because of higher shearing forces during compaction due to system dominance of plastic particles. This mixture range should therefore be avoided to get robust formulation.


α- amylase; microcrystalline cellulose; compressibility; percolation threshold.

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