Impact of surface roughness of pre-treated punches and powder properties on prevention of sticking during pharmaceutical tableting

In the present study, surface-modified punches with different roughness were evaluated for their ability to prevent sticking during pharmaceutical tableting using a single punch machine. The surface roughness of the punch faces was assessed using a laser microscope. Acetaminophen and ibuprofen were used as model active pharmaceutical ingredients (APIs) for the tableting tests. The amounts of API powders adhering to the punch faces after tableting were evaluated using spectrophotometric methods. Although the surfaces of the pre-treated punch faces were developed to prevent sticking during tableting, the sticking prevention was greater for acetaminophen than ibuprofen, and the sticking prevention was shown to depend on the mechanical properties of the API powders-namely, plasticity and elasticity. During continuous tableting the formulations, the surface modified punches maintained their anti-sticking properties. We concluded that characterization of the sticking properties by the present methods using a single punch machine is useful (1) to select the most suitable type of punch face for tableting a drug formulation without a large loss of expensive APIs, and (2) to solve the sticking problems without changing the pharmaceutical formulations during manufacturing.