Measuring the sticking of mefenamic acid powders on stainless steel surface

This study proposes an approach for quantifying the amount of pharmaceutical powder adhering (quality attribute) to the metals surfaces. The effect of surface roughness (detrimental attribute) on the amount of powder sticking to a stainless steel surface for a model pharmaceutical material is also qualitatively determined. Methodology to quantify powder adhesion to surfaces utilises a texture analyser and HPLC. The approach was validated to qualitatively investigate effect of metal surface roughness on adhesion of mefenamic acid. An increase in metal surface roughness resulted in an increase in cohesion. By increasing the average roughness from 289nm to 407nm, a 2.5 fold increase in amount adhering to metal was observed, highlighting the role of surface roughness on adhesion. The simplicity in experimental design with no requirement of specialised equipment and operational ease makes the approach very easy to adopt. Further, ease in interpreting results makes this methodology very attractive.