Particle engineering of excipients: A mechanistic investigation into the compaction properties of lignin and [co]-spray dried lignin

In this work, lignin was spray dried with sodium lauryl sulphate (SLS) in order to improve the compaction properties of lignin. Bulk level and physicochemical properties of spray dried formulations were measured and compared to as-received lignin and lactose which was used as a reference excipient. Single component tablets from individual powders were prepared and the mechanical properties of these powders were investigated by analysing force–displacement curves recorded during tableting, using a series of compaction equations. Moreover, the performance of these excipients in binary blends containing an active pharmaceutical ingredient (API) was investigated. A positive effect of SLS on the mechanical properties and bulk level properties of the spray dried formulations was observed. Spray dried formulations containing SLS showed superior flow properties to pure spray dried lignin while retaining similar particle size distributions. Spray dried formulations containing up to 10 w/w% SLS also showed superior compactibility in binary blends to as-received materials at porosity levels relevant for immediate release tablets. This study highlights the importance of understanding the compaction mechanics of single component powders as a means of predicting their behaviour in multi-component blends.